Teenage Pregnancy Essay Example for Free

Teenage Pregnancy Essay Challenges of Teenage Parenthood A. Parenthood Options B. Continuing Education C. Financial Problems V. Conclusion Teenage pregnancy is a major concern in todays society ;there are many ways to prevent teenage pregnancy, many people to get advice from, and many decisions a teenage parent must make. The statistics tell that the U. S. has the highest rate of teen pregnancy Teen Pregnancy Teen Pregnancy ; Parenting You sit there tense, your face is turning cherry red, your eyes are fixed on the little white machine, and you feel like the suspense is and births. More than 4 out of ten young women become pregnant at least once before they reach the age of 20-nearly one billion a year(Teen Pregnancy Facts and Stats 1). Teenage pregnancy has declined slowly but steadily. These recent declines reverse the 24-percent rise in the teenage birth rate from 1986 to 1991 (Teen Pregnancy Facts and Stats 1). Usually only one-third of teenage mothers receive a high school diploma. The rest of the mothers usually end Teen Pregnancy You sit there tense, your face is turning cherry red, your eyes are fixed on the little white machine, and you feel like the suspense is killing you, two minutes p on welfare. A majority of both boys and girls who are sexually active wish they had waited. Eight in ten girls and six in ten boys say they wish they had waited (Teen Pregnancy Facts and Stats 1). Many people are concerned about the problems teenage parents and their children face. The health risks for a teenage girl who becomes pregnant increase sharply. One of the concerns of teenage mothers is the health risk. Usually young women have Teen Pregnancy Teen Pregnancy Over the past two decades, the rates of teen pregnancy have grown dramatically. According to the Prevention of Teen Pregnancy, approximately every thirty-one seconds teenage pregnant in the more complications in pregnancy than older women. The most hazardous complication is low birth weight. One out of seven babies born to teenage mothers have a low birth weight (Hildebrand 88). Poor eating habits, smoking, or using alcohol or drugs, cause low birth weight. Premature babies and babies with low birth weights often have organs that havent fully developed, such as lungs, heart and brain. These babies get sick easier than normal weight babies. As a result Teen Pregnancy The situation is as follow: A teen girl (anywhere from the age thirteen to eighteen) finds herself in a sexual relationship with a male. The end result is from what was motioned above, teenage mothers are considered to be in the high-risk health category. They need good prenatal care as soon as they find out they are pregnant. A doctor, nurse, or other medical practitioner gives most of the information about nutrition. Prenatal care can help prevent pregnancy complications and improve ones chances of having a healthy baby. The best way to prevent teenage pregnancy, which is 100% effective, is abstinence. Most teenagers have a whole Teen pregnancy Teen Pregnancy There are a lot of teen mothers growing up in this world wondering, what if I would have stayed in school? What could I have become? life ahead of them and having a child will cause a lot of complications in your goals. Its not impossible for teenage mothers to complete high school, or try to reach their goals in life, but having a child could very well interfere with these goals. Another way of protection is condoms. There are a lot of protections out there, but these protections are not 100-percent reliable. There are a lot of places and people to go to Teen Pregnancy Teen Pregnancy There are a lot of teen mothers growing up in this world wondering, what if I would have stayed in school? What could I have become? for support and advice. In addition there are many organizations and hotlines a teenage mother can contact for advice and assistance. Parents and family are one alternative. There are a lot of teenagers that are afraid of their parents reactions. However, most parents are calmer and more supportive than teenagers expect. Most parents are shocked when the teenager comes and tells them that they are pregnant. Just give the parents time and they will try to give their Teen pregnancy Teen Pregnancy There are a lot of teen mothers growing up in this world wondering, what if I would have stayed in school? What could I have become? teenager the best advice that they know. The school nurse or counselor is another place to get advice. The counselor usually can gather up pamphlets and brochures about pregnancy. The counselor can also help the teenager remain in school. They are very supportive and understanding. Doctors and clinics are very important for a teenage parent to go to. There are a lot of home pregnancy tests available, but the doctor is a lot more reliable and gives

The real-time transport protocol

The real-time transport protocol Abstract This paper describes the Real-time Transport Protocol (RTP) with the emphasis on the securities, confidentiality and authenticity. This system takes a media file as input, encrypt it and create a message digest on the encrypted data then transmit it to the user. On the other side the receiver again calculate digest and compare it with the received one, if match occurs then decrypt and play it in the real time player. In current specification of RFC1889, only the confidentiality is described and authenticity is left for lower layer protocols. This work made experiment both on authenticity and confidentiality. For authenticity MD5, SHA-1 and SHA-2 hash algorithms can be used and for confidentiality AES-128 and Triple DES cryptographic algorithms can be used. In fact, SHA-2 is better than other hash algorithms in terms of security but SHA-1 is better than SHA-2 in terms of time efficiency. On the other hand, AES-128 is better than Triple DES in terms of time efficiency and security. So SHA-1and AES-128 is chosen for authenticity and confidentiality respectively for the security of RTP. The experiment is performed on J2SDK1.5. Keywords: Real-time transport protocol; Transport control protocol; Cryptographic algorithm; Hash algorithm. 1. Introduction: In recent days Computer and Internet has become essential part of human life and people demanding more and more access and use data over the Internet in Real-time with efficient secure manner. A new protocol Real-time Transport Protocol (RTP) and its associated Protocols helping people to use data over the Internet in their real-time applications. In this paper, the analyses of the securities of RTP, an approach to modify RTP for authenticity are presented. Also the position of RTP in Computer Network Layers, its usage scenario and the importance of time consideration to transmit streams using RTP are discussed and shown their analytical results. RTP is intended to be malleable to provide the information required by a particular application and will often be integrated into the application processing rather than being implemented as a separate layer. RTP is a modular protocol. The usage of RTP for a specific purpose requires an application area specific RTP profile. RTP profiles are used for refining the basic RTP protocol to suit for a particular application area. RTP profiles define how and by which formats data is encapsulated to RTP packets. RFC 1889 defines basic fields for the transportation of real time data. It also defines Real-time Transport Control Protocol (RTCP), whose purpose is to provide feedback on transmission quality, information about pa rticipants of RTP session, and enable minimal session control services. RTP is an application level protocol that is intended for delivery of delay sensitive content, such as audio and video, through different networks. The purpose of RTP is to facilitate delivery, monitoring, reconstruction, mixing and synchronization of data streams. RTP provides end-to-end network transport functions suitable for applications transmitting real-time data. RTP is a protocol framework that is deliberately not complete. RTP dose not provide quality of service means that it has no flow control, no error control, no acknowledgement and no mechanism to request retransmission. It does not do so because if a missing packet is retransmitted then it might happen that the retransmitted packet reach to the user too late to use which may hamper real-time use of streams. If some packets are lost during transmission (it is very common for Real-time protocols) then the lost packets are generated by interpolation rather than retransmission. However to improve performance of RTP another protocol; Real-time Transport Control Protocol is used with RTP. It handles feedback on delay, jitter, bandwidth, congestion, and other network properties. RTCP also handles inter stream synchronization. The problem is that different streams may use different clocks, with different granularities and different drift rates. RTCP can be used to keep them in synchronization. RTCP is also supports the use of RTP level translators and mixers. The paper is organized as follows. In section 2, RTP use scenarios are discussed. In section 3, position of RTP in computer network is discussed. In section 4, time consideration in RTP is discussed. In section 5, RTP packet format, its data transfer protocol and Real-time Transport control Protocol (RTCP) is discussed. Section 6 details the hash and cryptographic algorithms for RTP security while section 7 shows the result and performance analysis. Lastly, section 8 points out the conclusion inferred from the work. 2. RTP use scenarios: The following sections describe some aspects of the use of RTP. The examples are chosen to illustrate the basic operation of applications using RTP. In these examples, RTP is carried on top of IP and UDP and follows the conventions established by the profile for audio and video specified in the companion Internet-Draft draft-ietf-avt-profile. 2.1 Simple multicast audio conference: A working group of the IETF meets to discuss the latest protocol draft, using the IP multicast services of the Internet for voice communications. Through some allocation mechanism the working group chair obtains a multicast group address and pair of ports. One port is used for audio data, and the other is used for control (RTCP) packets. This address and port information is distributed to the intended participants. If privacy is desired, the data and control packets may be encrypted, in which case an encryption key must also be generated and distributed. The exact details of these allocation and distribution mechanisms are beyond the scope of RTP. The audio conferencing application used by each conference participant sends audio data in small chunks of, say, 20 ms duration. Each chunk of audio data is preceded by an RTP header; RTP header and data jointly form a UDP packet. The RTP header indicates what type of audio encoding (such as PCM, ADPCM or LPC) is contained in each packet so that senders can change the encoding during a conference, for example, to accommodate a new participant that is connected through a low-bandwidth link or react to indications of network congestion. The Internet, like other packet networks, occasionally loses and reorders packets and delays them by variable amounts of time. To cope with these impairments, the RTP header contains timing information and a sequence number that allow the receivers to reconstruct the timing produced by the source, so that in this example, chunks of audio are contiguously played out the speaker every 20 ms. This timing reconstruction is performed separately for each source of RTP packets in the conference. The sequence number can also be used by the receiver to estimate how many packets are being lost. Since members of the working group join and leave during the conference, it is useful to know who is participating at any moment and how well they are receiving the audio data. For that purpose, each instan ces of the audio application in the conference periodically multicasts a reception report plus the name of its user on the RTCP (control) port. The reception report indicates how well the current speaker is being received and may be used to control adaptive encoding. In addition to the user name, other identifying information may also be included subject to control bandwidth limits. A site sends the RTCP BYE packet when it leaves the conference. 2.2 Audio and Video Conference: If both audio and video media are used in a conference, they are transmitted as separate RTP sessions RTCP packets are transmitted for each medium using two different UDP port pairs and/or multicast addresses. There is no direct coupling at the RTP level between the audio and video sessions, except that a user participating in both sessions should use the same distinguished (canonical) name in the RTCP packets for both so that the sessions can be associated. One motivation for this separation is to allow some participants in the conference to receive only one medium if they choose. Despite the separation, synchronized playback of a sources audio and video can be achieved using timing information carried in RTCP packets for both sessions 2.3 Mixers and translators: So far, it is assumed that all sites want to receive media data in the same format. However, this may not always be appropriate. Consider the case where participants in one area are connected through a low-speed link to the majority of the conference participants who enjoy high-speed network access. Instead of forcing everyone to use a lower-bandwidth, reduced-quality audio encoding, an RTP-level relay called a mixer may be placed near the low-bandwidth area. This mixer resynchronizes incoming audio packets to reconstruct the constant 20 ms spacing generated by the sender, mixes these reconstructed audio streams into a single stream, translates the audio encoding to a lower-bandwidth one and forwards the lower-bandwidth packet stream across the low-speed link. These packets might be unicast to a single recipient or multicast on a different address to multiple recipients. The RTP header includes a means for mixers to identify the sources that contributed to a mixed packet so that corr ect talker indication can be provided at the receivers. Some of the intended participants in the audio conference may be connected with high bandwidth links but might not be directly reachable via IP multicast. For example, they might be behind an application-level firewall that will not let any IP packets pass. For these sites, mixing may not be necessary; in which case another type of RTP-level relay called a translator may be used. Two translators are installed, one on either side of the firewall, with the outside one funneling all multicast packets received through a secure connection to the translator inside the firewall. The translator inside the firewall sends them again as multicast packets to a multicast group restricted to the sites internal network. Mixers and translators may be designed for a variety of purposes. An example is a video mixer that scales the images of individual people in separate video streams and composites them into one video stream to simulate a group scene. Other examples of translation include the connection of a group of hosts speaking only IP/UDP to a group of hosts that understand only ST-II, or the packet-by-packet encoding translation of video streams from individual sources without resynchronization or mixing. 3. Position of RTP in computer network: As a consequence it is decided to put RTP in user space but should run over User Datagram Protocol (UDP, it is connectionless transport protocol). RTP operates as follows. The multimedia (streams) application consists of multiple audio, video, text and possibly other streams. These are fed into the RTP library, which is in user space along with the application. This library then multiplexes the streams and encodes those RTP packers, which it then stuffs into a socket. At the other end of socket (in the operating system kernel), UDP packets are generated and embedded in IP packets. If computer is on an Ethernet, the IP packets are then put in Ethernet frames for transmission. The protocol stack for this situation is shown in Figure 1. Since RTP runs in user space not in OS kernel and in the Ethernet it packed by UDP, then IP and then Ethernet, so it is difficult which layer RTP is in. But it is linked to application program and it is generic, application independent protocol that just provides transport facilities, so it is a transport protocol that is implemented in the application layer. The packet nesting is shown in Figure 2. The main goal of RTP is to make the transmitting streams real-time applicable. On the other hand if security is provided to the transmitting streams, then some extra time is needed to encrypt the streams or to make signature such as making digest from entire movie or audio files. So in concern of time, security is added with some overheads to the RTP. The goal of this paper is to choose algorithms and procedures that make RTP reliable in term of time and security. 4. Time consideration in RTP: Let a video or audio file over the Internet in real-time is intended to access, then here the most important parameter is bandwidth of the Network. And the next important parameters are minimum clip size and its duration as well as processors speed of both server and client. At first let it be assumed that files are accessing without security consideration. Then let review the following mathematical calculations for audio or video clip to access in real-time. One second file clip size = oneSecFileSize bits, Time duration of each clip = cSec seconds, Upload Transmission rate = uRate bits per second, Download Transmission rate = dRate bits per second, Time to upload, tUpload = oneSecFileSize *cSec/uRate, Time to download, tDownload = oneSecFileSize If the time to upload or download a clip is more than the time to play a clip, the player will wait and the receiver will see a break, i.e. max (tUpload, tDownload) >cSec. For the continuous playing of clips, the following condition must be true: Max (1/uRate, 1/dRate) > 1/ oneSecFileSize Min (uRate, dRate) > oneSecFileSize According to the equation, the waiting time between clips at the receiver does not depend on clip size. The only variable that matters for a continuous playback is the size of a one-second file and that the provided upload and download rates meet the above condition. Lag time between playing and capturing is: cSec + tupload + tdownload From the above equation, the maximum lag with no break in the feed is 3*cSec and the minimum lag is cSec. To get the clip as close to real time as possible, cSec should be reduced. Next, apply the above analysis to the following cases: 4.1 Both sender and receiver have a low bandwidth modem connection: Lets assume the uRate = dRate = 20K bits/sec. In this case, the one-second file size should be less than 20Kbits. If the clip size is 10 seconds, the maximum playback lag will be 30 seconds. It is observed that the minimum file size for transmitting a one-second video (with no audio) is 8Kbits using H263 encoding and 12896 pixels video size. It is also observed a minimum file size with the video and an 8-bit mono audio with an 8000Hz-sampling rate to be 80Kbits. 4.2 Either the sender or the receiver has a low bandwidth connection: Lets assume that the lower rate is 20Kbits/sec and the other rate is much higher. In this case the one-second file size should be less than 20Kbits, but the maximum playback lag is about 20 seconds if the clip size is 10 seconds. 4.3 Both sender and receiver have high bandwidth: It is noted here that the one-second-clip size may vary from the format to format of the file, that is, how the file is encoded. For example the one-second-clip size of MP3 is less than in WAV file. But the important point here is that when cryptographic algorithms are applied in the clip then an extra time is added to the processing of clip with each side. So if applied strong encryption algorithms to the clip then extra more time is needed to both sides and upload or download time will be affected and time lag between them will also be changed. So real time access of data is also affected. Therefore, providing security in RTP the considered parameters are bandwidth of the network, file format of clips, upload and download of the clip, processor and memory speed and applying cryptographic and hash algorithms. 5. RTP packet format and data transfer protocol: RTP packet formats and its Data Transfer Protocol is as follows: 5.1 RTP fixed header files: Whenever data are transferred with RTP, it always add a fixed header with the payload. The RTP header has the following format shown in figure 4: The first twelve octets are present in every RTP packet, while the list of CSRC identifiers is present only when inserted by a mixer. Version (V) is 2 bits wide. This field identifies the version of RTP. The version defined by this specification is two (2). Padding (P) is 1 bit wide. If the padding bit is set, the packet contains one or more additional padding octets at the end which are not part of the payload. The last octet of the padding contains a count of how many padding octets should be ignored. Padding may be needed by some encryption algorithms with fixed block sizes or for carrying several RTP packets in a lower-layer protocol data unit. Extension (X) is 1 bit wide. If the extension bit is set, the fixed header is followed by exactly one header extension. CSRC Count (CC) is 4 bits wide. The CSRC count contains the number of CSRC identifiers that follow the fixed header. Marker (M) is 1 bit wide. The interpretation of the marker is defined by a profile. It is intended to al low significant events such as frame boundaries to be marked in the packet stream. A profile may define additional marker bits or specify that there is no marker bit by changing the number of bits in the payload type field. Payload type (PT) is 7 bits wide. This field identifies the format of the RTP payload and determines its interpretation by the application. A profile specifies a default static mapping of payload type codes to payload formats. Additional payload type codes may be defined dynamically through non-RTP means. An initial set of default mappings for audio and video is specified in the companion profile Internet-Draft draft-ietf-avt-profile, and may be extended in future editions of the Assigned Numbers RFC [9]. An RTP sender emits a single RTP payload type at any given time; this field is not intended for multiplexing separate media streams. Sequence number is 16 bits wide. The sequence number increments by one for each RTP data packet sent, and may be used by the rece iver to detect packet loss and to restore packet sequence. The initial value of the sequence number is random (unpredictable) to make known-plaintext attacks on encryption more difficult, even if the source itself does not encrypt, because the packets may flow through a translator that does. Time stamp is 32 bits wide. The timestamp reflects the sampling instant of the first octet in the RTP data packet. The sampling instant must be derived from a clock that increments monotonically and linearly in time to allow synchronization and jitter calculations. The resolution of the clock must be sufficient for the desired synchronization accuracy and for measuring packet arrival jitter (one tick per video frame is typically not sufficient). The clock frequency is dependent on the format of data carried as payload and is specified statically in the profile or payload format specification that defines the format, or may be specified dynamically for payload formats defined through non-RTP mean s. If RTP packets are generated periodically, the nominal sampling instant as determined from the sampling clock is to be used, not a reading of the system clock. As an example, for fixed-rate audio the timestamp clock would likely increment by one for each sampling period. If an audio application reads the blocks covering 160 sampling periods from the input device, the timestamp would be increased by 160 for each such block, regardless of whether the block is transmitted in a packet or dropped as silent. The initial value of the timestamp is random, as for the sequence number. Several consecutive RTP packets may have equal timestamps if they are (logically) generated at once, e.g., belong to the same video frame. Consecutive RTP packets may contain timestamps that are not monotonic if the data is not transmitted in the order it was sampled, as in the case of MPEG interpolated video frames. SSRC is 32 bits wide. The SSRC field identifies the synchronization source. This identifier i s chosen randomly, with the intent that no two synchronization sources within the same RTP session will have the same SSRC identifier although the probability of multiple sources choosing the same identifier is low, all RTP implementations must be prepared to detect and resolve collisions. If a source changes its source transport address, it must also choose a new SSRC identifier to avoid being interpreted as a looped source. The CSRC list contains 0 to15 items, 32 bits each. The CSRC list identifies the contributing sources for the payload contained in this packet. The number of identifiers is given by the CC field. If there are more than 15 contributing sources, only 15 may be identified. CSRC identifiers are inserted by mixers, using the SSRC identifiers of contributing sources. For example, for audio packets the SSRC identifiers of all sources that were mixed together to create a packet is listed, allowing correct talker indication at the receiver. 5.2 Multiplexing RTP sessions: For efficient protocol processing, the number of multiplexing points should be minimized. In RTP, multiplexing is provided by the destination transport address (network address and port number), which defines an RTP session. For example, in a teleconference composed of audio and video media encoded separately, each medium should be carried in a separate RTP session with its own destination transport address. It is not intended that the audio and video be carried in a single RTP session and demultiplexed based on the payload type or SSRC fields. Interleaving packets with different payload types but using the same SSRC would introduce several problems: If one payload type were switched during a session, there would be no general means to identify which of the old values the new one replaced. An SSRC is defined to identify a single timing and sequence number space. Interleaving multiple payload types would require different timing spaces if the media clock rates differ and would require different sequence number spaces to tell which payload type suffered packet loss. The RTCP sender and receiver reports can only describe one timing and sequence number space per SSRC and do not carry a payload type field. An RTP mixer would not be able to combine interleaved streams of compatible media into one stream. Carrying multiple media in one RTP session precludes: the use of different network paths or network resource allocations if appropriate; reception of a subset of the media if desired, for example just audio if video would exceed the available bandwidth; and receiver implementations that use separate processes for the different media, whereas using separate RTP sessions permits either single- or multiple-process implementations. Using a different SSRC for each medium but sending them in the same RTP session would avoid the first three problems but not the last two. 5.3 Profile-Specific modifications to the RTP header: The existing RTP data packet header is believed to be complete for the set of functions required in common across all the application classes that RTP might support. However, in keeping with the ALF design principle, the header may be tailored through modifications or additions defined in a profile specification while still allowing profile-independent monitoring and recording tools to function. The marker bit and payload type field carry profile-specific information, but they are allocated in the fixed header since many applications are expected to need them and might otherwise have to add another 32-bit word just to hold them. The octet containing these fields may be redefined by a profile to suit different requirements, for example with a more or fewer marker bits. If there are any marker bits, one should be located in the most significant bit of the octet since profile-independent monitors may be able to observe a correlation between packet loss patterns and the marker bit. Addit ional information that is required for a particular payload format, such as a video encoding, should be carried in the payload section of the packet. This might be in a header that is always present at the start of the payload section, or might be indicated by a reserved value in the data pattern. If a particular class of applications needs additional functionality independent of payload format, the profile under which those applications operate should define additional fixed fields to follow immediately after the SSRC field of the existing fixed header. Those applications will be able to quickly and directly access the additional fields while profile-independent monitors or recorders can still process the RTP packets by interpreting only the first twelve octets. If it turns out that additional functionality is needed in common across all profiles, then a new version of RTP should be defined to make a permanent change to the fixed header. 5.4 RTP header extension: An extension mechanism is provided to allow individual implementation to experiment with new payload-format-independent functions that require additional information to be carried in the RTP data packet header. This mechanism is designed so that the header extension may be ignored by other interoperating implementations that have not been extended. Note that this header extension is intended only for limited use. Most potential uses of this mechanism would be done better another way, using the methods described in the previous section. For example, a profile-specific extension to the fixed header is less expensive to process because it is not conditional nor in a variable location. Additional information is required for a particular payload format should not use this header extension but should be carried in the payload section of the packet. If the X bit in the RTP header is one, a variable-length header extension is appended to the RTP header, following the CSRC list if present. Th e RTP header extension is shown in figure 5: The header extension contains a 16-bit length field that counts the number of 32-bit words in the extension, excluding the four-octet extension header (therefore zero is a valid length). Only a single extension may be appended to the RTP data header. To allow multiple interoperating implementations to each experiment independently with different header extensions, or to allow a particular implementation to experiment with more than one type of header extension, the first 16 bits of the header extension are left open for distinguishing identifiers or parameters. The format of these 16 bits is to be defined by the profile specification under which the implementations are operating. This RTP specification does not define any header extensions itself. 5.5 Real-time Transport Control Protocol (RTCP): RTCP is a coordination protocol of RTP. It provides some tasks to increase the performance of RTP. The RTP control protocol (RTCP) is based on the periodic transmission of control packets to all participants in the session, using the same distribution mechanism as the data packets. The underlying protocol must provide multiplexing of the data and control packets, for example using separate port numbers with UDP. RTCP performs four functions: The primary function is to provide feedback on the quality of the data distribution. This is an integral part of the RTPs role as a transport protocol and is related to the flow and congestion control functions of other transport protocols. The feedback may be directly useful for control of adaptive encodings, but experiments with IP multicasting have shown that it is also critical to get feedback from the receivers to diagnose faults in the distribution. Sending reception feedback reports to all participants allows one who is observing problems to evaluate whether those problems are local or global. With a distribution mechanism like IP multicast, it is also possible for an entity such as a network service provider who is not otherwise involved in the session to receive the feedback information and act as a third-party monitor to diagnose network problems. This feedback function is performed by the RTCP sender and receiver reports. RTCP carries a persistent transport-level identifier for an RTP source called the canonical name or CNAME. Since the SSRC identifier may change if a conflict is discovered or a program is restarted, receivers require the CNAME to keep track of each participant. Receivers also require the CNAME to associate multiple data streams from a given participant in a set of related RTP sessions, for example to synchronize audio and video. The first two functions require that all participants send RTCP packets; therefore the rate must be controlled in order for RTP to scale up to a large number of participants. By having each participant send its control packets to all the others, each can independently observe the number of participants. This number is used to calculate the rate at which the packets are sent. A fourth, optional function is to convey minimal session control information, for example participant identification to be displayed in the user interface. This is most likely to be useful in loosely controlled sessions where participants enter and leave without membership control or parameter negotiation. RTCP serves as a convenient channel to reach all the participants, but it is not necessarily expected to support all the control communication requirements of an application. A higher-level session control protocol, which is beyond the scope of this document, may be needed. Functions (i)-(iii) are mandatory when RTP is used in the IP multicast environment, and are recommended for all environments. RTP application designers are advised to avoid mechanisms that can only work in unicast mode and will not scale to larger numbers. 5.6 RTCP transmission interval: RTP is designed to allow an application to scale automatically over session sizes ranging from a few participants to thousands. For example, in an audio conference the data traffic is inherently self-limiting because only one or two people will speak at a time, so with multicast distribution the data rate on any given link remains relatively constant independent of the number of participants. However, the control traffic is not self-limiting. If the reception reports from each participant were sent at a constant rate, the control traffic would grow linearly with the number of participants. Therefore, the rate must be scaled down. For each session, it is assumed that the data traffic is subject to an aggregate limit called the session bandwidth to be divided among the participants. This bandwidth might be reserved and the limit enforced by the network, or it might just be a reasonable share. The session bandwidth may be chosen based or some cost or a priori knowledge of the available network bandwidth for the session. It is somewhat independent of the media encoding, but the encoding choice may be limited by the session bandwidth. The session bandwidth parameter is expected to be supplied by a session management application when it invokes a media application, but media applications may also set a default based on the single-sender data bandwidth for the encoding selected for the session. The application may also enforce bandwidth limits based on multicast scope rules or other criteria. Bandwidth calculations for control and data traffic include lower- layer transport and network protocols (e.g., UDP and IP) since that are what the resource reservation system would need to know. The application can also be expected to know which of these protocols are in use. Link level headers a

tundra :: essays research papers

The tundra artic plains completely covering most of the earth’s lands north of the coniferous forest belt. The tundra’s ecosystem is very sensitive. It doesn’t have a good ability to restore itself. Controlled by sedge, heath, willow, moss, and lichen. Plains that are pretty much alike, called alpine tundra, occur above the timberline in the high mountains of the world. Even the Antarctic area has a couple of its own arctic regions itself.   Ã‚  Ã‚  Ã‚  Ã‚  The climate of the tundra is characterized by harsh winters. The average temperature in the tundra area is about –27 degrees. But what is even worse are the long night. At nights the lowest temperture recorded was –67.36 degrees. There are even times in the year when the sun doesn’t come up for days. In the tundra we have little snow and even less rainfall. The rainfall is about a quarter inch in a yearly rainfall. Even though the tundra’s winters are long a harsh there summers are the shortest season of all. Do to the terrible weather and climate in the tundra their animals and plant life is very limited. This artic tundra is mainly formed by permafrost, â€Å"a layer of permanently frozen subsoil in the ground. Putting frozen ground and flat landscape stops the drainage of water. As the water is being held up on the surface it makes ponds and bogs that give moisture for the plants, or countering the low precipitation. â€Å"The periodic freezing and thawing of the soil forms cracks in the ground in regularly patterned polygons†. Some areas are not drained very well causing irregular landforms. Some of these landforms like the following hummocks, or knolls, frost boils, and earth stripes. Another common area to the alpine tundra is a â€Å"bare rock covered ground† also known as fell fields, in which not alone support but helps the growth of lichens. The many â€Å"microhabitats† given by these landforms provide a variety to the tundra’s landscape. As you already know the amount of different plant species in the tundra is very few. Also their growth level is low, â€Å"with most of the biomass concentrated in the roots. To add to the many difficulties the growing season isn’t very long its self. The plants are better off â€Å"to reproduce vegetative by division and budding than sexually by flower pollination†. The main plant life in that area is cotton grass, sedge, and dwarf heath also including mosses and lichens. tundra :: essays research papers The tundra artic plains completely covering most of the earth’s lands north of the coniferous forest belt. The tundra’s ecosystem is very sensitive. It doesn’t have a good ability to restore itself. Controlled by sedge, heath, willow, moss, and lichen. Plains that are pretty much alike, called alpine tundra, occur above the timberline in the high mountains of the world. Even the Antarctic area has a couple of its own arctic regions itself.   Ã‚  Ã‚  Ã‚  Ã‚  The climate of the tundra is characterized by harsh winters. The average temperature in the tundra area is about –27 degrees. But what is even worse are the long night. At nights the lowest temperture recorded was –67.36 degrees. There are even times in the year when the sun doesn’t come up for days. In the tundra we have little snow and even less rainfall. The rainfall is about a quarter inch in a yearly rainfall. Even though the tundra’s winters are long a harsh there summers are the shortest season of all. Do to the terrible weather and climate in the tundra their animals and plant life is very limited. This artic tundra is mainly formed by permafrost, â€Å"a layer of permanently frozen subsoil in the ground. Putting frozen ground and flat landscape stops the drainage of water. As the water is being held up on the surface it makes ponds and bogs that give moisture for the plants, or countering the low precipitation. â€Å"The periodic freezing and thawing of the soil forms cracks in the ground in regularly patterned polygons†. Some areas are not drained very well causing irregular landforms. Some of these landforms like the following hummocks, or knolls, frost boils, and earth stripes. Another common area to the alpine tundra is a â€Å"bare rock covered ground† also known as fell fields, in which not alone support but helps the growth of lichens. The many â€Å"microhabitats† given by these landforms provide a variety to the tundra’s landscape. As you already know the amount of different plant species in the tundra is very few. Also their growth level is low, â€Å"with most of the biomass concentrated in the roots. To add to the many difficulties the growing season isn’t very long its self. The plants are better off â€Å"to reproduce vegetative by division and budding than sexually by flower pollination†. The main plant life in that area is cotton grass, sedge, and dwarf heath also including mosses and lichens.

Intergumentary System Essay example -- Biology, Organisms, Atoms

Organisms are composed of atoms that form molecules which form macromolecules (Shier, Butler, & Lewis, 2009). These molecules join and form organelles which structure cell that for tissues (p.3). Tissues form organs and the organs working together form organ system (p3). These organ systems make up the organism (p3). Each organ system has an important function in the body. These systems all work together in order to keep and support the conditions that the cells, tissues, and organs need to function properly. There is one system that is not as well known as other; it is the intergumentary system. Most people know the organs of the intergumentary system, but they do not know that these organs work together to form this system. The intergumentary system is composed of the skin and the structures related to the skin, which include the hair, the finger nails, the sensory receptors and the glands (Shier, Butler, & Lewis, 2009). This system has an important function since it provides protection to the body, helps to maintain body temperature, and contains sensory receptors (p.117). The skin which is the largest organ in the body and an organ of the intergumentary system has essential function such as regulating homeostasis and body temperature, also delaying the loss of water from deeper tissues, storing sensory receptor, synthesizing biomechanical, and discharging waste from the body (p.117). The skin has two layers: the epidermis (outer layer) and the dermis (inner layer) (p.117). There is also a subcutaneous layer or hypodermis (Shier, Butler, & Lewis, 2009). According to Shier, Butler, and Lewis 2009 â€Å"as its name indicates, this layer is beneath the skin and not a true layer of the skin.† This layer has the blood vessels that su... ...se glands help to balance the body temperature (p.124). The fluid that this eccrine glands secret is transported outside of the body by a tube that has an opening to the exterior as a pore (p.124). Another sweat gland is the apocrine gland which is activated at puberty. According to Shier, Butler, and Lewis 2009 â€Å"these glands secrete by the same mechanism as eccrine glands, usually when a person is emotionally upset, frightened, in pain, or during sexual arousal.† Other sweat glands are seruminous glands which secret, and the female mammary glands which secrete milk (p.124). The nails which are another accessory of the skin cover and give protection to the end of fingers and toes (Shier, Butler, & Lewis, 2009). The nails have a lunula which is the area of growth in the nail (p.122). This means that if the lunula is damaged the nail probably will not growth again.

Graduation Speech: Take Off Your Masks :: Graduation Speech, Commencement Address

What an honor to be standing here tonight as a representative of the Class of 2012! It's truly remarkable. We have all worked very hard to complete this part of our journey. I want to thank my kids Laddie, and Mate. And especially Ron, my loving companion. Without the support of our families, friends, fellow-classmates, instructors and staff, we wouldn't have made it this far! Let's show 'em our appreciation. These three certificates I'm receiving tonight represent a lot more to me than achievement of success. They are the keys that unlocked the door to a whole new world of possibility that I never new existed. I'd like to begin with an Arabian proverb: Strange how much you've got to know, before you know how little you know. Two years ago, I was a single mother of four, with a learning disability and 15 years of sobriety. I began experiencing anxiety attacks so I ceased operation of a non-profit organization I founded and ran for 10 years called the Family Support Network. Even though I had received a number of prestigious awards and been recognized nationally for my work, I resigned myself to being a clerical assistant for the rest of my life. Though I had dreamed of going to college, it was simply out of the question. It was at this juncture in my life that something happened that I initially perceived as a tragic event, but it turned out to be a turning point in my life. The mask I wore for so many years that covered my fears and insecurities about myself was removed, and I finally had an explanation for my quirky behaviors. One day I collapsed on the job and was hospitalized - not in a regular hospital but in a psychiatric hospital. The doctors diagnosed my symptoms as post traumatic stress disorder. In addition, I was also diagnosed with a mood and anxiety disorder. My self-esteem and outlook on life was at an all time low. It was at this point I hit bottom - and to my surprise this became the beginning of my journey to fulfill my destiny. My doctor in her infinite wisdom suggested I supplement my therapy by taking classes in mental health and chemical dependency here at the college. I'm sure by now you are wondering why I am sharing such intimate details about myself. My intent is to inspire and challenge you at the same time.

Film Scene Analysis On Racism Depicted In The Movie Crash Essay

In the film Crash we are given a picture of all different kinds of social and multicultural differences, giving us an eye opening and often disturbing examples of racism that damages our society. The scene I have chosen to analyze is between 18:30 – 21:05 minutes in the movie Crash. Cameron and Christine are a black well off couple. They experience stereotyping and racism when they are driving home from a party. A white police officer pulls them over and performs a search on both Cameron and Christine. This scene illustrates the social and racial tensions, with a racist white officer molesting an innocent black woman. The scene is located in a residential neighborhood, in an American City. Although the time of date is not stated it is very dark and probably late at night as there a few cars that pass through the entire scene. There is a Christmas tree in the background, suggesting that this is set during the winter. Although it is dark and gloomy, we can depict that it is cold as Cameron is wearing a turtleneck and blazer, and the policeman are also wearing jackets. The scene revolves around four major characters, Cameron (Husband), Christine (Wife), Officer John, and Officer Tom. Cameron and Christine are pulled over by the two officers whilst driving a Black Navigator. The cop car is directly behind the black navigator, however most of the scene takes place near the Black Navigator. Around the characters there are a few malnourished trees, alongside with blurred streetlights and shop signs. There are glimpses of residential houses in the background indicating that they are in a suburban area. Cameron’s costume is a beige turtleneck, with a Dark brown blazer and black dress pants. He is also wearing a wedding ring, black leather strap watch, and frameless glasses. Christine is wearing a white cocktail dress, with the majority of her body exposed. She is wearing diamond earrings and a wedding ring. Officer John and Tom are wearing police issued jackets, black button down  shirt, black pants and black leather shoes. There is a police badge stitched into the jacket, and on the left arm of the jacket showing their rank. Throughout the scene the dialogue is accompanied by a faint eerie melody that is played at slow tempo. As Officer John is molesting Christine the camera starts to follow John’s hands up and down her backside. Most of the time the camera is focused on the characters faces, to allow the viewer a deeper insight into the situation. Cameron and Christine are both of African decent, and first generation Americans. Christine mentions at the start that Cameron is a Buddhist, and does not drink; however Christine does not oblige to the same lifestyle. Cameron is 5ft10, 40-50 years old, around 160-180 pounds and has his hair slick back. Christine is 5ft7, 40-50 years old, around 120-140 pounds and has her hair tied back. Officer John is around 5ft10-11, 30-40 years old; around 170-190 pounds, and slick back hair. Officer Tom is a younger version of John, around the ages of 20-30, same height and around 150-170 pounds with unpolished hair. When Cameron and Christine are pulled over by the Police, they smile at each other as if they just cracked a joke. When the police officers approach the vehicle and ask Cameron to step out the car, Christine loses it and starts mouthing off at Officer John calling him a â€Å"cracker†, boiling his blood. A key moment in the scene is when Christine searched by Officer John, and glares at Cameron signaling for help. Cameron makes eye contact and looks away in sadness signaling there is nothing he can do. Although Cameron does not speak out, we can clearly tell he is in distress and controlling his anger displayed through non-verbal behavior (Elliot Aronson et Al, 2012). While Officer John runs his hands down Christine’s backside he constantly glances at Cameron showing him the distribution of power in this situation. Although Cameron may be a movie director, John proves to him he is an officer of the law and holds more power than his money can buy. Officer Tom handles contains Cameron as he is forced to watch his partner perform sinful acts on the poor housewife. Through his facial expressions we can depict that he is clearly uncomfortable with his partner’s action, however he is unable to act against them. Officer John clearly outranks Tom in terms of superiority, and must follow his orders. Officer John is portrayed as a troubled racist white that feels the need to establish his racial dominance and authority. Although this could have been a long stemming hatred towards blacks (Attribution Theory (Elliot Aronson et Al, 2012)), it seems that an incident prior to the scene may have triggered his reaction. An Availability Heuristic (Elliot Aronson; Timothy D. Wilson; Robin M. Akert, 2012) may have readily been available for John when he saw a black man receiving fellatio from either a white/black female. Christine as mentioned before is slightly drunk throughout the scene, and starts mouthing off at Officer John. Although both Cameron and Christine realize that this is an act of racism Christine acted out of line by turning a bad situation into a worse one. In a way she was acting out of her Gender Role (Elliot Aronson et Al, 2012) as the male should be the one to deal with situations like this. In the marriage vows it says that you must protect your partner at all times, and is a common known fact when associating Gender Roles (Elliot Aronson et Al, 2012). The traditionally male roles of â€Å"provider† and â€Å"protector† are especially examined when the police officer is molesting Christine, and Cameron just watches in silence and despair. It is arguable that when confronted by police there are certain Demand Characteristics (Elliot Aronson et Al, 2012) that should be done, however in this case Cameron acted like a coward. It is interesting to observe the interaction between Cameron and Christine throughout the scene. Cameron shows his male dominance by telling Christine to â€Å"Shut Up, Stop Talking† and stay out of the situation. This proves that Cameron’s Social Cognition (Elliot Aronson et Al, 2012) is that he is in power and that his wife should listen to his words. Another key thing that was observed during the analysis was that Cameron was more afraid of the consequences against his own future career than his wife. To elaborate Cameron knew that if he intervened with Officer John he would be arrested and be all over the news. He was more concerned with his own image than his wife, which is why he stood there helplessly watching. Once the officers left, we can see that Cameron has been morally degraded and on the verge of succumbing into insanity. Christine starts to blame Cameron for his cowardly actions, although he does not seem to care much on the outside we can depict that it is doing a number on him mentally. When I first  watched this scene I was shocked to see Officer John abuse his power, whilst at the same time surprised to see Cameron and Officer Tom watch helplessly. Especially Cameron being her husband he shows no signs to try and help Christine. This scene is a clear example of Modern Racism (Elliot Aronson et Al, 2012), and how certain roles in society have the ability to abuse their power. It is also very interesting to see how social psychology plays a big role in how certain people make decisions. Such as Christine speaking out of place, John molesting Christine, and Tom and Cameron acting as innocent bystanders. References Elliot Aronson; Timothy D. Wilson; Robin M. Akert (2012), Social Psychology, Eight Edition, New Jersey, Pearson Education Inc, Retrieved from Coursesmart Library

Reaction Paper- Rizal Essay

â€Å"Does Rizal deserve to be our national hero?† This article written by Renato Constantino, is all about Rizal that does he really deserves to be a hero or not? The author compared Rizal to others national heroes in different countries, who is most decisively active in the fight for their freedom and leader of that revolution. Like in US, China, Vietnam and other countries mentioned from the article. But the author said Rizal is not our Revolution leader; in fact he repudiated that revolution. He’s just silent and being martyr for our country. Also he is an American-Sponsored Hero, Rizal chose as a model over other contestants- Aguinaldo too militant, Bonifacio too radical, Mabini unregenerate. We must view Rizal as an evolving personality within historical period. Additional, author’s purpose for this article is to remind us that our history is very important to us because it will serve to demonstrate how our presence has been distorted by a faulty knowledge of our past. For me, this article was still a question to the author of â€Å"Does Rizal deserves to be our National Hero?† There are several factors that Rizal deserves it and some are not. Because Rizal had certain qualities, he was able to serve the pressing social needs of the periods, needs that arose out of general and particular historical forces. As the author said, he is a hero in the sense that he was able to see problems generated by historical forces, discern the new social needs created by the historical development of new social relationships, and take an active part in meeting these needs. But he is not a hero in the sense of he could have stopped and altered the course of events. Although Rizal was already a revered figure and became more so after his martyrdom, it cannot be denied that his pre-eminence among heroes was partly the result of American sponsorship. Also, he was the first Filipino limited Filipino, the ilustrado Filipino, who fought for national unity but feared the Revolution and loved his mother country, yes, but in his own ilustrado way. Rizal never advocated independence, nor did he advocate armed resistance to the government. He urged from within by publicity, by public education, and appeal to the public conscience. What  if Rizal is not our National hero? Maybe Bonifacio can be our National hero because he fights for our country and he is too revolutionary. When the goals of the people are finally achieved, Rizal the first Filipino will be canceled by the true Filipino by whom he will be remembered as a great catalyst in the transformation of the decolonized indios. But still, there are so many reason that Rizal deserves to be our National Hero. So, I think the author balanced this view of article. The author explained the opinion of both. Honestly, I am not really interested about this article. There are so many questions in my mind says, â€Å"it happened, he’s our national hero, what are these articles complaining or explaining† â€Å"why do we need to study about this?† But it’s required to us to read this article and make a reaction paper to this, and then I realized that it is important to us (Filipino) to understand our history. We must understand why Rizal is our national hero. It is also a reflection of our intellectual timidity, our reluctance to expose new causes unless we can find authorize, however remote, in Rizal. The exposure of his weaknesses and limitations will also mean our liberation, for he has, to a certain extent become part of the superstructure that supports present consciousness. That is why a critical evaluation of Rizal cannot but lead to a revision of our understanding of history and the role of the individual in history. I conclude that Rizal deserves to be our National Hero. If I would ask the author, what if Rizal is not our National Hero, who it will be? Why?