Male Bird Song Evolves in order to Attract a Female for Mating Research Paper

Male Bird Song Evolves in order to Attract a Female for Mating - Research Paper Example Further these qualities are also indicators of the physiological characteristics and genotype of the male partner and thus have high likelihood of influencing female choice. However the study of birdsong and its evolutionary significance in influencing female choice is yet at its infancy. Many new aspects are beginning to emerge. Deriving conclusions and making generalization at this stage would be inappropriate and inaccurate. MALE BIRD SONG EVOLVES IN ORDER TO ATTRACT A FEMALE FOR MATING INTRODUCTION Birdsong can be defined as long complex vocalizations produced mainly in breeding season (Catchpole & Slater, 1995). The best known birds in terms of their singing abilities are oscine birds, also referred to as passerines or perching birds. They belong to the order Passeriformes and are classified on the basis of their unique musculature of the syrinx or the vocal organ (Warner, 1972). In most of the temperate species of passerines, the males are exclusively the singers. The male bird sings either as a means of expression during male-male aggression or for attracting the female (Catchpole & Slater, 1995). ... BACKGROUND Communication is a primary requisite for functional ability. Humans must communicate to form relationships, fulfil their needs, organize and function. Animals communication is essential for food gathering, reproduction and survival; the three basic needs of all animals. However, unlike humans animals do not speak. In fact all animals possess their unique methods of communication (Hauser, 2000). Flowers send signals in form of fragrances and colour at the time of bloom to insects for pollination; meerkats communicate through scent, sounds and body language; lions communicate through body contact and sound, while birds communicate verbally through songs and coos (Rowe & Skelhorn, 2004). Communication systems, irrespective of nature and origin, comprise of two essential components: signal and tactical design. The signal is an important carrier of information from the sender to the receiver. In researches involving communication, study of nature of signal as an important deter minant of its goal is pursued (Rowe & Skelhorn, 2004). The signal evolution is in accordance with the function it is expected to perform. This is termed as strategic component of the signal (Guilford & Dawkins, 1991). Tactical design encompasses the properties of the communication determined by the transmission characteristics of the environment and the sensory and perceptual abilities of the receiver. To define the latter the term â€Å"receiver Psychology† was introduced by Guilford and Dawkins (1991) and was considered a significant determinant of the evolution of signals. Studies on bio-acoustics or animal sounds can be traced back to a research paper published by

Nursing Assignment Essay Example | Topics and Well Written Essays - 1500 words

Nursing Assignment - Essay Example (Delaune 2006, p. 4). Female nurses, on the other hand, dominate the nursing profession. Females are also the gender being first thought by the public when nursing profession is being talked about. Both of these gender reported inequalities in different health care settings in terms of strength, knowledge and skills, as well as salary issues. But of all gender-related equality issues, the effect of Florence Nightingale to the image of nursing profession affects the male population more. Men have fared in a profession traditionally dominated by women and most of the male population suffered from gender inequality. Most of the nursing care during eleventh to thirteenth centuries was rendered by men. It was not until late nineteenth century that females dominated the nursing profession. Florence Nightingale created a big impact in excluding men from the field of nursing. Nightingale’s work had proved that nursing is a profession fit for the female discipline. Florence Nightingale left behind the contributions of men in nursing and view men’s role as physical support aid or a patient’s assistant. The Industrial Revolution also plays a role in the exit of men from nursing. During this time, science-related profession such as medicine shall be taken by the male population and nursing to the female population (Chitty 2005, p. 71). In late 1800, Mills Nursing School for Men in New York and McLean Asylum Training School in Massachusetts were the first two nursing schools established for men. The only field being considered for them is psychiatric nursing because this requires strength and stamina. In 1901 and 1908, the US Congress established the Army Nurse Corpse and Navy Nurse Corpse. However, this was restricted to women so men find it difficult to enter the military nursing. In addition, during 1941, only 68 out of 1,303 schools accepted men as nursing student (Chitty 2005, p. 71). After World War II, the efforts of men to join the field of nurs ing were recognized. GI Bill helped to increase the number of male students by providing funds for education and training. Men entering nursing schools increase after the World War II. Men have truly suffered from gender inequality It is evident from nursing leaders influence, public perception, school discrimination, and military restrictions. In the contemporary age, there are also cases of gender inequality throughout the world but there are no restrictions for male nurses in whatever field in nursing they would like to take. Men can choose from several nursing schools today without fear of being rejected. The public also views both men and women as part of the nursing profession with men, being equally caring, competitive, and compassionate as women. Gender inequality issues still occur in some areas but with the influence of contemporary era, cases reported were minimal. Nursing profession of today does not look into gender differences but to the knowledge, skills, and motivati on related to nursing care. Nursing Image: Professional Nurses Dress Code The professional nurses’ dress code reflects the nursing image. During the early times, one can easily distinguish a person belonging to the nurse profession. But now, the public found it difficult to know who exactly are the registered nurses. The New York Training School for Nurses at Bellevue Hospital was the first school to adopt a standard uniform for student nurses. In

Types of assessment Essay Example for Free

Types of assessment Essay What is meant by assessment? What are the strengths and weaknesses of the assessment types and methods you use? How would you involve your learner into the assessment process? Why do we need to keep records of assessment? Assessments are a critical part of the education system; highlighted by Black and Wiliams’(1998) who define assessments as activities providing â€Å"information to be used as feedback to modify the teaching and learning activities in which they are engaged†. There are two forms of assessment; formative and summative. Formative assessments are carried  out as the course progresses. These are an informal and simple way of gauging how and what your students are learning. This then allows teachers to amend their teaching to accommodate the results as evaluation and reflection takes place. Furthermore students can identify the areas of development and ‘ensure that objectives are being met’ (Minton,1991, p183). Feedback is therefore considered to be significant for the continued development and progression of learners (Petty, 2010). Summative assessment, however, refers to a more traditional approach for testing learners. see more:describe how to find out the history preferences wishes and needs of an individual It  involves assessing learners at the end of the course/year providing a final grade. Summative assessment can be very effective, however, it could be very demanding for an adult with learning disabilities as they may find it difficult to recollect information from the beginning of the course. Initial assessment should take place before a learner begins the course; these are ‘an evaluation of a learner’s skills, knowledge, strengths and areas for development. ’ (Gravells, 2012). This is effective when working with adults with learning disabilities as it will help establish the appropriate  pitch, pace and content/resources to be used. Furthermore, it will be a way of recognising prior learning and such experience/qualifications can be validated. Rules of assessment should be adhered to ensure equality and fair testing: they should be valid, reliable, authentic, current and sufficient. Teachers/Assessors should not discriminate against learners in their choice of assessment method and planning and should advance anti-discriminatory practice. There are many forms of assessment strategies in English; these include speaking and listening assessments, controlled assessments, quizzes/worksheets, essays etc. Speaking and listening assessments are means of measuring a learners’ communication skills. Individuals are assessed on their ability to project their ideas, viewpoints and their listening skills. This allows learners to work in a group, supporting each other by sharing ideas and improve their functional skills. Furthermore, it can be videoed as evidence. However, it is difficult to assess the level of understanding of the learners through this method alone. Furthermore, this is a subjective strategy and feedback can be limited. Worksheets and quizzes both can be set as individual or group work. They provide an objective mark at the end which can lead to informative feedback based on the learner’s strengths, weaknesses and areas for improvement. The tasks can be fun, engaging and interesting for learners. This strategy has reliability because worksheets/quizzes are consistent as similar results can be gained. Furthermore, they are valid because they measure understanding as the learners attempt to answer questions and the marks obtained shows the stage, progress and understanding of each learner. The benefits are highly valuable as the learners enjoy completing the activities. Mitchells (1997) recognised that games and quizzes can be motivating for those learners who struggle with formal teaching styles. Other assessments include observation, watching and evaluating the learners’ progress. Observations should reflect a learner’s daily performance and should be recorded fully on paper; audiotape or video, with an awareness of confidentiality issues, signed and dated by the teacher/assessor and learner. The more detailed and factual the record, the stronger the evidence may be in terms of validity and reliability. Such observations should be planned in advance with the 1 / 3  agreement of the learner’s manager and colleagues. However, teachers can take opportunities to record observations of unplanned events, if useful as evidence. Through observations, teacher/assessor can gather sufficient evidence and can then relate the observation back to many different units/elements of the qualification. Also, it allows teachers to see natural competence first hand in an authentic and reliable manner. Nevertheless, there are disadvantages of observations: A learner’s normal duties may not cover all assessment criteria; observations may be unnerving for learners and observations can take a lot of  an assessor’s time and expense. Brookfield’s (1998) model of reflection states that it is critical that one views themselves and their teaching through the perspective of their learners. In this lens there is a strong focus on the learner’s ‘voice’ and so value is placed on their viewpoints and also their articulation of work. Therefore, it is important to gain the learners’ thoughts on the assessment strategy. Learners should be informed of how they will be assessed from the onset, involved in feedback and evaluation at every level. Furthermore, prior to assessment, learners could be shown a model  answer and given success criterion to ensure they understand how to achieve the desired level/grade. Involving learners in the assessment process is a key way of helping them to manage and ‘take ownership’ of their learning, by reflecting on achievement and progress. Involving them in recording their own and each others’ progress and planning the next steps in learning can deepen their understanding and reinforce their sense of achievement. Therefore they should be briefed about expectations, purpose and benefits of becoming involved in assessment. Self-assessment will allow learners to reflect upon their own progress and assesses their own development and achievements. However, self-assessment is not always easy and teachers should guide learners in a step-by-step process so they learn how to evaluate their own work and learning style, perhaps by modelling. Reid (2011) suggests that you can use other learners if, for example, they observed your learner. This refers to peer assessment, where peers assess the learner’s developments and achievements through observation of their practice during an activity. Peer assessment and feedback activities give students opportunities to internalise the criteria, learn from examples, enables evaluation and reflection and allows development of responsibility for own learning. However there might be some drawbacks from this as some students may express concerns about showing their work to others that are not qualified to assess their work. Also, it needs to be reliable and accurate; therefore strategies need to be put into place to ensure objectivity. Records are an integral part of the teaching and learning process. Gravells (2012) argues that  records must be maintained, to support the teaching and learning process and to satisfy auditors, inspectors, regulators, verifiers, internal and external quality assurers and your own organisation’s requirements. Teachers should retain documents such as the syllabus, scheme of work, session plans, action plans, hand-outs/activities for the learner, and assessment records such as tracking sheets, marked assignments, portfolios etc. Holding records of the course and content would allow inspections on the manner in which the course is being taught and to ensure it is being delivered in accordance to  specifications. Teacher must also keep records of learners’ progression. This will identify whether the student is on task to complete course or having difficulty. Clear, concise information and evidence will lead to a greater understanding of learner needs and enable teachers to amend their teaching styles to accommodate the learner needs. Records must be kept for a length of time stipulated by your organisation in case of an auditing process. However under the Data Protection Act 1998, this information should be â€Å"kept secure with appropriate technical and organisational measures taken to  protect the information’ and confidentiality should be maintained. A very good explanation of why records must be kept in an institute. 2 / 3 Word count: 1102 (excluding references) References Benjamin S Bloom. (1980), All Our Children Learning, New York: McGraw-Hill. Black, P. , amp; Wiliam, D. (1998), Inside the Black Box: Raising standards through classroom assessment. King’s College London School of Education, pg 2 Brookfield, S. (1998) Critically reflective teacher. Journal of Continuing Education in the Health Professions Data Protection Act (2008), Information Commissioners Office, lt; www.ico. gov. ukgt; Date accessed 21/02/14 Gravells, A. (2012) Preparing to Teach in the Lifelong Learning Sector (5th Edition) Learning Matters Ltd Exeter Minton, D. , (1991), Teaching Skills in Further and Adult Education, Macmillan Press Ltd. Mitchell, C. (1997), Transforming Teaching; Selecting and evaluating teaching strategies. Further Education Matters. Petty, G. (2010) Teaching Today Home page, http://www. geoffpetty. com/, 201O Read, H, (2011) The Best Assessor’s Guide. Bideford: Read On Publications POWERED BY TCPDF (WWW. TCPDF. ORG).

Design of Spatial Decoupling Scheme

Design of Spatial Decoupling Scheme Design of Spatial Decoupling Scheme using Singular Value Decomposition for Multi-User Systems Abstract In this paper, we present the use of a polynomial singular value decomposition (PSVD) algorithm to examine a spatial decoupling based block transmission design for multiuser systems. This algorithm facilitates joint and optimal decomposition of matrices arising inherently in multiuser systems. Spatial decoupling allows complex multichannel problems of suitable dimensionality to be spectrally diagonalized by computing a reduced-order memoryless matrix through the use of the coordinated transmit precoding and receiver equalization matrices. A primary application of spatial decoupling based system can be useful in discrete multitone (DMT) systems to combat the induced crosstalk interference, as well as in OFDM with intersymbol interference. We present here simulation-based performance analysis results to justify the use of PSVD for the proposed algorithm. Index Terms-polynomial singular value decomposition, paraunitary systems, MIMO system. INTRODUCTION Block transmission based systems allows parallel, ideally noninterfering, virtual communication channels between multiuser channels. Minimally spatial decoupling channels are needed whenever more than two transmitting channels are communicate simultaneously. The channel of our interest here, is the multiple input multiple output channels, consisting of multiple MIMO capable source terminals and multiple capable destinations. This scenario arises, obviously, in multi-user channels. Since certain phases of relaying involves broadcasting, it also appears in MIMO relaying contexts. The phrase MIMO broadcast channel is frequently used in a loose sense in the literature, to include point-to-multipoint unicast (i.e. private) channels carrying different messages from a single source to each of the multiple destinations (e.g. in multi-user MIMO). Its use in this paper is more specific, and denotes the presence of at least one common virtual broadcast channel from the source to the destinations. The use of iterative and non-iterative spatial decoupling techniques in multiuser systems to achieve independent channels has been investigated, for instance in [1]-[9]. Their use for MIMO broadcasting, which requires common multipoint-to-multipoint MIMO channels is not much attractive, given the fact that the total number of private and common channels is limited by the number of antennas the source has. Wherever each receiver of a broadcast channel conveys what it receives orthogonally to the same destination, as in the case of pre-and post-processing block transmission, the whole system can be envisaged as a single point-to-point MIMO channel. Block transmission techniques have been demonstrated for point-to-point MIMO channels to benefit the system complexities. Other advantages includes: (i) channel interference is removed by creating $K$ independent subchannels; (ii) paraunitarity of precoder allows to control transmit power; (iii) paraunitarity of equalizer does not amplify the channel noise; (iv) spatial redundancy can be achieved by discarding the weakest subchannels. Though the technique outperform the conventional signal coding but had its own demerits.   Amongst many, it shown in cite{Ta2005,Ta2007} that an appropriate additional amount of additive samples  still require individual processing, e.g. per- tone equalisation, to remove ISI, and   the receiver does not exploit the case of structured noise. However, the choice of optimal relay gains, although known for certain cases (e.g. [10], [11]), is not straightforward with this approach. Since the individual equalization have no non-iterative means of decoding the signals, this approach cannot be used with decode-and-forward (DF), and code-and-forward (CF) relay processing schemes. The use of zero-forcing at the destination has been examined [12], [13] as a mean of coordinated beamforming, since it does not require transmitter processing. The scheme scales to any number of destinations, but requires each destination to have no less antennas than the source. Although not used as commonly as the singular value decomposition (SVD), generalized singular value decomposition (GSVD) [14, Thm. 8.7.4] is not unheard of in the wireless literature. It has been used in multi-user MIMO transmission [15], [16], MIMO secrecy communication [17], [18], and MIMO relaying [19]. Reference [19] uses GSVD in dual-hop AF relaying with arbitrary number of relays. Since it employs zero-forcing at the relay for the forward channel, its use of GSVD appears almost similar to the use of SVD in [1]. Despite GSVD being the natural generalization of SVD for two matrices, we are yet to see in the literature, a generalization of SVD-based beamforming to GSVD-based beamforming. Although the purpose and the use is somewhat different, the reference [17, p.1] appears to be the first to hint the possible use of GSVD for beamforming. In present work, we illustrate how GSVD can be used for coordinated beamforming in source-to-2 destination MIMO broadcasting; thus in AF, DF and CF MIMO relaying. We also present comparative, simulation-based performance analysis results to justify GSVD-based beamforming. The paper is organized as follows: Section II presents the mathematical framework, highlighting how and under which constraints GSVD can be used for beamforming. Section III examines how GSVD-based beamforming can be applied in certain simple MIMO and MIMO relaying configurations. Performance analysis is conducted in section IV on one of these applications. Section V concludes with some final remarks. Notations: Given a matrix A and a vector v, (i) A(i, j)  gives the ith element on the jth column of A; (ii) v(i)  {ˆ y1 }R(r+1,r+s) = ˜Π£{x }R(r+1,r+s) + _ UHn1 _ R(r+1,r+s) ,   {ˆ y2 }R(pà ¢Ã‹â€ Ã¢â‚¬â„¢t+r+1,pà ¢Ã‹â€ Ã¢â‚¬â„¢t+r+s) = ˜Άº{x }R(r+1,r+s) + _ VHn2 _ R(pà ¢Ã‹â€ Ã¢â‚¬â„¢t+r+1,pà ¢Ã‹â€ Ã¢â‚¬â„¢t+r+s) , {ˆ y1 }R(1,r) = {x }R(1,r) + _ UHn1 _ R(1,r) , {ˆ y2 }R(pà ¢Ã‹â€ Ã¢â‚¬â„¢t+r+s+1,p) = {x }R(r+s+1,t) + _ VHn2 _ R(pà ¢Ã‹â€ Ã¢â‚¬â„¢t+r+s+1,p) . (1)  gives the element of v at the ith position. {A}R(n) and  {A}C(n) denote the sub-matrices consisting respectively of the  first n rows, and the first n columns of A. Let {A}R(m,n)  denote the sub-matrix consisting of the rows m through n  of A. The expression A = diag (a1, . . . , an) indicates that  A is rectangular diagonal; and that first n elements on its  main diagonal are a1, . . . , an. rank (A) gives the rank of  A. The operators ( à £Ã†â€™Ã‚ » )H, and ( à £Ã†â€™Ã‚ »)à ¢Ã‹â€ Ã¢â‚¬â„¢1 denote respectively the  conjugate transpose and the matrix inversion. C mÃÆ'-n is the  space spanned by mÃÆ'-n matrices containing possibly complex  elements. The channel between the wireless terminals T1 and  T2 in a MIMO system is designated T1 à ¢Ã¢â‚¬  Ã¢â‚¬â„¢T2.   II. MATHEMATICAL FRAMEWORK Let us examine GSVD to see how it can be used for  beamforming. There are two major variants of GSVD in the  literature (e.g. [20] vs. [21]). We use them both here to  elaborate the notion of GSVD-based beamforming. A. GSVD Van Loan definition Let us first look at GSVD as initially proposed by Van Loan [20, Thm. 2]. Definition 1: Consider two matrices, H à ¢Ã‹â€ Ã‹â€ C mÃÆ'-n with  m à ¢Ã¢â‚¬ °Ã‚ ¥n, and G à ¢Ã‹â€ Ã‹â€ C pÃÆ'-n, having the same number n of  columns. Let q = min (p, n). H and G can be jointly  decomposed as H = UÃŽÂ £Q, G = VΆºQ (2) where (i) U à ¢Ã‹â€ Ã‹â€ C mÃÆ'-m,V à ¢Ã‹â€ Ã‹â€ C pÃÆ'-p are unitary, (ii) Q à ¢Ã‹â€ Ã‹â€  C nÃÆ'-n non-singular, and (iii) ÃŽÂ £= diag (à Ã†â€™1, . . . , à Ã†â€™n) à ¢Ã‹â€ Ã‹â€  C mÃÆ'-n, à Ã†â€™i à ¢Ã¢â‚¬ °Ã‚ ¥0; Άº= diag (ÃŽÂ »1, . . . , ÃŽÂ »q) à ¢Ã‹â€ Ã‹â€ C pÃÆ'-n, ÃŽÂ »i à ¢Ã¢â‚¬ °Ã‚ ¥0. As a crude example, suppose that G and H above represent  channel matrices of MIMO subsystems S à ¢Ã¢â‚¬  Ã¢â‚¬â„¢D1 and S à ¢Ã¢â‚¬  Ã¢â‚¬â„¢D2  having a common source S. Assume perfect channel-stateinformation  (CSI) on G and H at all S,D1, and D2. With  a transmit precoding matrix Qà ¢Ã‹â€ Ã¢â‚¬â„¢1, and receiver reconstruction  matrices UH,VH we get q non-interfering virtual broadcast channels. The invertible factor Q in (2) facilitates jointprecoding  for the MIMO subsystems; while the factors U,V   allow receiver reconstruction without noise enhancement. Diagonal  elements 1 through q of ÃŽÂ £,Άºrepresent the gains  of these virtual channels. Since Q is non-unitary, precoding  would cause the instantaneous transmit power to fluctuate. This is a drawback not present in SVD-based beamforming. Transmit signal should be normalized to maintain the average  total transmit power at the desired level. This is the essence of GSVD-based beamforming for  a single source and two destinations. As would be shown  in Section III, this three-terminal configuration appears in  various MIMO subsystems making GSVD-based beamforming  applicable. B. GSVD Paige and Saunders definition Before moving on to applications, let us appreciate GSVDbased  beamforming in a more general sense, through another  form of GSVD proposed by Paige and Saunders [21, (3.1)]. This version of GSVD relaxes the constraint m à ¢Ã¢â‚¬ °Ã‚ ¥n present  in (2). Definition 2: Consider two matrices, H à ¢Ã‹â€ Ã‹â€ C mÃÆ'-n and  G à ¢Ã‹â€ Ã‹â€ C pÃÆ'-n, having the same number n of columns. Let CH = _ HH,GH _ à ¢Ã‹â€ Ã‹â€ C nÃÆ'-(m+p), t = rank(C), r = t à ¢Ã‹â€ Ã¢â‚¬â„¢rank (G) and s = rank(H) + rank (G) à ¢Ã‹â€ Ã¢â‚¬â„¢t. H and G can be jointly decomposed as H = U (ÃŽÂ £ 01 )Q = UÃŽÂ £{Q}R(t) , G = V (Άº 02 )Q = VΆº{Q}R(t) , (3) where (i) U à ¢Ã‹â€ Ã‹â€ C mÃÆ'-m,V à ¢Ã‹â€ Ã‹â€ C pÃÆ'-p are unitary, (ii) Q à ¢Ã‹â€ Ã‹â€ C nÃÆ'-n non-singular, (iii) 01 à ¢Ã‹â€ Ã‹â€ C mÃÆ'-(nà ¢Ã‹â€ Ã¢â‚¬â„¢t), 02 à ¢Ã‹â€ Ã‹â€  C pÃÆ'-(nà ¢Ã‹â€ Ã¢â‚¬â„¢t) zero matrices, and (iv) ÃŽÂ £Ãƒ ¢Ã‹â€ Ã‹â€ C mÃÆ'-t,ΆºÃƒ ¢Ã‹â€ Ã‹â€  C pÃÆ'-t have structures ÃŽÂ £_ à ¢Ã… ½Ã¢â‚¬ º à ¢Ã… ½Ã‚  IH ˜Π£ 0H à ¢Ã… ½Ã… ¾ à ¢Ã… ½Ã‚   and Άº_ à ¢Ã… ½Ã¢â‚¬ º à ¢Ã… ½Ã‚  0G ˜Άº IG à ¢Ã… ½Ã… ¾ à ¢Ã… ½Ã‚  . IH à ¢Ã‹â€ Ã‹â€ C rÃÆ'-r and IG à ¢Ã‹â€ Ã‹â€ C (tà ¢Ã‹â€ Ã¢â‚¬â„¢rà ¢Ã‹â€ Ã¢â‚¬â„¢s)ÃÆ'-(tà ¢Ã‹â€ Ã¢â‚¬â„¢rà ¢Ã‹â€ Ã¢â‚¬â„¢s) are identity  matrices. 0H à ¢Ã‹â€ Ã‹â€ C (mà ¢Ã‹â€ Ã¢â‚¬â„¢rà ¢Ã‹â€ Ã¢â‚¬â„¢s)ÃÆ'-(tà ¢Ã‹â€ Ã¢â‚¬â„¢rà ¢Ã‹â€ Ã¢â‚¬â„¢s), and 0G à ¢Ã‹â€ Ã‹â€  C (pà ¢Ã‹â€ Ã¢â‚¬â„¢t+r)ÃÆ'-r are zero matrices possibly having no  rows or no columns. ˜Π£= diag (à Ã†â€™1, . . . , à Ã†â€™s) ,˜Άº= diag (ÃŽÂ »1, . . . , ÃŽÂ »s) à ¢Ã‹â€ Ã‹â€ C sÃÆ'-s such that 1 > à Ã†â€™1 à ¢Ã¢â‚¬ °Ã‚ ¥. . . à ¢Ã¢â‚¬ °Ã‚ ¥ à Ã†â€™s > 0, and à Ã†â€™2 i + ÃŽÂ »2i = 1 for i à ¢Ã‹â€ Ã‹â€  {1, . . . , s}. Let us examine (3) in the MIMO context. It is not difficult  to see that a common transmit precoding matrix _ Qà ¢Ã‹â€ Ã¢â‚¬â„¢1 _ C(t) and receiver reconstruction matrices UH,VH would jointly  diagonalize the channels represented by H and G.  For broadcasting, only the columns (r+1) through (r +s)  of ÃŽÂ £and Άºare of interest. Nevertheless, other (t à ¢Ã‹â€ Ã¢â‚¬â„¢s)  columns, when they are present, may be used by the source  S to privately communicate with the destinations D1 and configuration # common channels # private channels S à ¢Ã¢â‚¬  Ã¢â‚¬â„¢ {D1,D2} S à ¢Ã¢â‚¬  Ã¢â‚¬â„¢D1 S à ¢Ã¢â‚¬  Ã¢â‚¬â„¢D2 m > n,p à ¢Ã¢â‚¬ °Ã‚ ¤n p n à ¢Ã‹â€ Ã¢â‚¬â„¢p 0 m à ¢Ã¢â‚¬ °Ã‚ ¤n, p > n m 0 n à ¢Ã‹â€ Ã¢â‚¬â„¢m m à ¢Ã¢â‚¬ °Ã‚ ¥n, p à ¢Ã¢â‚¬ °Ã‚ ¥n n 0 0 m + p à ¢Ã‹â€ Ã¢â‚¬â„¢n n à ¢Ã‹â€ Ã¢â‚¬â„¢p n à ¢Ã‹â€ Ã¢â‚¬â„¢m (m + p) > n n à ¢Ã¢â‚¬ °Ã‚ ¥(m + p) 0 m p TABLE I NUMBERS OF COMMON CHANNELS AND PRIVATE CHANNELS FOR  DIFFERENT CONFIGURATIONS D2. It is worthwhile to compare this fact with [22], and  appreciate the similarity and the conflicting objectives GSVDbased  beamforming for broadcasting has with MIMO secrecy  communication. Thus we can get ˆ y1 à ¢Ã‹â€ Ã‹â€ C mÃÆ'-1, ˆ y2 à ¢Ã‹â€ Ã‹â€ C pÃÆ'-1 as in (1) at  the detector input, when x à ¢Ã‹â€ Ã‹â€ C tÃÆ'-1 is the symbol vector  transmitted. It can also be observed from (1) that the private  channels always have unit gains; while the gains of common  channels are smaller. Since, à Ã†â€™is are in descending order, while the ÃŽÂ »is ascend  with i, selecting a subset of the available s broadcast channels  (say k à ¢Ã¢â‚¬ °Ã‚ ¤s channels) is somewhat challenging. This highlights  the need to further our intuition on GSVD. C. GSVD-based beamforming Any two MIMO subsystems having a common source  and channel matrices H and G can be effectively reduced,  depending on their ranks, to a set of common (broadcast) and  private (unicast) virtual channels. The requirement for having  common channels is rank (H) + rank (G) > rank (C) where C = _ HH,GH _ H. When the matrices have full rank, which is the case with  most MIMO channels (key-hole channels being an exception),  this requirement boils down to having m +p > n . Table I  indicates how the numbers of common channels and private  channels vary in full-rank MIMO channels. It can be noted  that the cases (m > n,p à ¢Ã¢â‚¬ °Ã‚ ¤n) and (m à ¢Ã¢â‚¬ °Ã‚ ¥n, p à ¢Ã¢â‚¬ °Ã‚ ¥n)  correspond to the form of GSVD discussed in the Subsection II-A. Further, the case n à ¢Ã¢â‚¬ °Ã‚ ¥(m + p) which produces only  private channels with unit gains, can be seen identical to zero  forcing at the transmitter. Thus, GSVD-based beamforming is  also a generalization of zero-forcing. Based on Table I, it can be concluded that the full-rank  min (n,m + p) of the combined channel always gets split  between the common and private channels. D. MATLAB implementation A general discussion on the computation of GSVD is found  in [23]. Let us focus here on what it needs for simulation:  namely its implementation in the MATLAB computational  environment, which extends [14, Thm. 8.7.4] and appears as  less restrictive as [21]. The command [V, U, X, Lambda, Sigma] = gsvd(G, H);  gives1 a decomposition similar to (3). Its main deviations  from (3) are,   1Reverse order of arguments in and out of gsvd function should be noted. ) ) D1 y1 , r1 S x ,w ( ( ) ) D2 y2 , r2 _ H1 __ n1 _ __ H2 n2 Fig. 1. Source-to-2 destination MIMO broadcast system  Ãƒ ¢Ã¢â€š ¬Ã‚ ¢ QH = X à ¢Ã‹â€ Ã‹â€ C nÃÆ'-t is not square when t . Precoding  for such cases would require the use of the pseudo-inverse  operator. à ¢Ã¢â€š ¬Ã‚ ¢ ÃŽÂ £has the same block structure as in (3). But the structure  of Άºhas the block 0G shifted to its bottom as follows: Άº_ à ¢Ã… ½Ã¢â‚¬ º à ¢Ã… ½Ã‚  ˜Άº IG 0G à ¢Ã… ½Ã… ¾ à ¢Ã… ½Ã‚  . This can be remedied by appropriately interchanging the  rows of Άºand the columns of V. However, restructuring  ÃƒÅ½Ã¢â‚¬ ºis not a necessity, since the column position of the  block ˜Άºwithin Άºis what matters in joint precoding.   Following MATLAB code snippet for example jointly  diagonalizes H,G to obtain the s common channels (3)  would have given. MATLAB code % channel matrices H = (randn(m,n)+i*randn(m,n))/sqrt(2); G = (randn(p,n)+i*randn(p,n))/sqrt(2); % D1, D2: diagonalized channels [V,U,X,Lambda,Sigma] = gsvd(G,H); w = X*inv(X*X); C = [H G]; t = rank(C); r = t rank(G); s = rank(H)+rank(G)-t; D1 = U(:,r+1:r+s)*H*w(:,r+1:r+s); D2 = V(:,1:s)*G*w(:,r+1:r+s); III. APPLICATIONS Let us look at some of the possible applications of GSVDbased beamforming. We assume the Van Loan form of GSVD  for simplicity, having taken for granted that the dimensions  are such that the constraints hold true. Nevertheless, the Paige  and Saunders form should be usable as well. A. Source-to-2 destination MIMO broadcast system   Consider the MIMO broadcast system shown in Fig. 1,  where the source S broadcasts to destinations D1 and D2.  MIMO subsystems S à ¢Ã¢â‚¬  Ã¢â‚¬â„¢D1 and S à ¢Ã¢â‚¬  Ã¢â‚¬â„¢D2 are modeled  to have channel matrices H1 ,H2 and additive complex   Gaussian noise vectors n1 , n2. Let x = [x1, . . . , xn]T ) ) R1 y1 , F1 ( ( S x ,w ( ( ) ) D y3 ,r1 y4 ,r2 ) ) R2 y2 , F2 ( ( _ ___ H3 _ n3 H1 ___ n1 _ ___ H2 n2 _ H4 ___ n4 Fig. 2. MIMO relay system with two 2-hop-branches  be the signal vector desired to be transmitted over n à ¢Ã¢â‚¬ °Ã‚ ¤Ã‚  min (rank (H1 ) , rank (H2 )) virtual-channels. The source  employs a precoding matrix w. The input y1 , y2 and output ˆ y1 , ˆ y2 at the receiver filters   r1 , r2 at D1 and D2 are given by y1 = H1wx + n1 ; ˆ y1 = r1 y1 , y2 = H2wx + n2 ; ˆ y2 = r2 y2 . Applying GSVD we get H1 = U1 ÃŽÂ £1 V and H2 = U2 ÃŽÂ £2V. Choose the precoding matrix w = ÃŽÂ ± _ Và ¢Ã‹â€ Ã¢â‚¬â„¢1 _ C(n) ; and receiver reconstruction matrices r1 = _ U1 H _ R(n) _ , r2 = U2 H _ R(n) . The constant ÃŽÂ ± normalizes the total average transmit power. Then we get, ˆ y1(i) = ÃŽÂ ±ÃƒÅ½Ã‚ £1(i, i) x(i) + Ëœn1(i) , ˆ y2(i) = ÃŽÂ ±ÃƒÅ½Ã‚ £2(i, i) x(i) + Ëœn2(i), ià ¢Ã‹â€ Ã‹â€  {1 . . . n}, where Ëœn1 , Ëœn2 have the same noise distributions as n1 , n2 .  B. MIMO relay system with two 2-hop-branches (3 time-slots) Fig. 2 shows a simple MIMO AF relay system where a  source S communicates a symbol vector x with a destination  D via two relays R1 and R2. MIMO channels S à ¢Ã¢â‚¬  Ã¢â‚¬â„¢R1, S à ¢Ã¢â‚¬  Ã¢â‚¬â„¢ R2, R1 à ¢Ã¢â‚¬  Ã¢â‚¬â„¢D and R2 à ¢Ã¢â‚¬  Ã¢â‚¬â„¢D are denoted: Hi , i à ¢Ã‹â€ Ã‹â€  {1, 2, 3, 4}. Corresponding channel outputs and additive complex Gaussian  noise vectors are yi , ni for i à ¢Ã‹â€ Ã‹â€  {1, 2, 3, 4}. Assume relay  operations to be linear, and modeled as matrices F1 and F2 . Assume orthogonal time-slots for transmission. The source  S uses w as the precoding matrix. Destination D uses  different reconstruction matrices r1 , r2 during the time slots  2 and 3. Then we have: Time slot 1: y1 = H1wx + n1 , y2 = H2wx + n2 Time slot 2: y3 = H3 F1 y1 + n3 Time slot 3: y4 = H4 F2 y2 + n4 Let ˆ y = r1 y3 +r2 y4 be the input to the detector. Suppose n à ¢Ã¢â‚¬ °Ã‚ ¤min i (rank (Hi )) virtual-channels are in use. ) ) R y1 , F ( ( S x ,w ( ( ) ) D y2 ,r1 y3 ,r2 _ ___ H3 _ n3 H1 ___ n1 H2 _ n2 Fig. 3. MIMO relay system having a direct path and a relayed path  Applying GSVD on the broadcast channel matrices we get H1 = U1 ÃŽÂ £1 Q and H2 = U2 ÃŽÂ £2 Q. Through SVD we  obtain H3 = V1 Άº1 R1 H and H4 = V2 Άº2 R2 H. Choose w = ÃŽÂ ± _ Qà ¢Ã‹â€ Ã¢â‚¬â„¢1 _ C(n) ; F1 = R1U1 H; F2 = R2U2 H; r1 = _ V1 H _ R(n) ; r2 = _ V2 H _ R(n) . The constant ÃŽÂ ± normalizes  the total average transmit power. Then we get

Mill on Liberty Essay examples -- essays research papers

In Chapter 2, Mill turns to the issue of whether people, either through their government or on their own, should be allowed to coerce or limit anyone else's expression of opinion. Mill emphatically says that such actions are illegitimate. Even if only one person held a particular opinion, mankind would not be justified in silencing him. Silencing these opinions, Mill says, is wrong because it robs "the human race, posterity as well as the existing generation." In particular, it robs those who disagree with these silenced opinions. Mill then turns to the reasons why humanity is hurt by silencing opinions. His first argument is that the suppressed opinion may be true. He writes that since human beings are not infallible, they have no authority to decide an issue for all people, and to keep others from coming up with their own judgments. Mill asserts that the reason why liberty of opinion is so often in danger is that in practice people tend to be confident in their own rightness, and excluding that, in the infallibility of the world they come in contact with. Mill contends that such confidence is not justified, and that all people are hurt by silencing potentially true ideas. After presenting his first argument, Mill looks at possible criticisms of his reasoning and responds to them. First, there is the criticism that even though people may be wrong, they still have a duty to act on their "conscientious conviction." When people are sure that they are right, they would be cowardly not to act on that belief and to allow doctrines to be expressed that they believe will hurt mankind. To this, Mill replies that the only way that a person can be confident that he is right is if there is complete liberty to contradict and disprove his beliefs. Humans have the capacity to correct their mistakes, but only through experience and discussion. Human judgment is valuable only in so far as people remain open to criticism. Thus, the only time a person can be sure he is right is if he is constantly open to differing opinions; there must be a standing invitation to try to disprove his beliefs. Second, there is the criticism that governments have a duty to uphold certain beliefs that are important to the well being of society. Only "bad" men would try to undermine these beliefs. Mill replies that this argument still relies on an assumption of i... ...s beliefs are not reflected in their conduct. As a result, people do not truly understand the doctrines they hold dear, and their misunderstanding leads to serious mistakes. Mill presents one possible criticism of this view. He writes that it could be asked whether it is essential for "true knowledge" for some people to hold erroneous opinions. Mill replies that having an increasing number of uncontested opinions is both "inevitable and indispensable" in the process of human improvement. However, this does not mean that the loss of debate is not a drawback, and he encourages teachers to try to compensate for the loss of dissent. Mill then turns to a fourth argument for freedom of opinion. He writes that in the case of conflicting doctrines, perhaps the most common case is that instead of one being true and one false, the truth is somewhere between them. Progress usually only substitutes one partial truth for another, the newer truth more suited to the needs of the times. Dissenting or heretical opinions often reflect the partial truths not recognized in popular opinion, and are valuable for bringing attention to a "fragment of wisdom." This fact can

Drugs And Alcoholism: Why Are Teenagers Involved? :: essays research papers

Adolescence is much like a midpoint in ones life; when a person is neither a kid nor an adult. At this period, teens have passed the age when they were called kids but are not yet qualified to be adults. Teenagers want to think like adults, behave like adults and also start to view themselves as independent beings in decision making. All this hormonal changes also come with the negativity of maturity such as drugs and alcohol. The statistics below show that the percentage of teenagers using drugs and alcohol in the last decade has increased. Why is this? The answer is that teenagers are under pressure by their peers, mass media and also the influence of parents. 8th-Graders10th-Graders12th-Graders Marijuana22.2%40.9%49.7% Cocaine4.77.79.8 Inhalants15.417.019.7 LSD4.18.512.2 Heroin2.02.32.3 Alcohol52.170.680.0 Cigarettes44.157.664.6 Peer pressure plays a major role in the harmful behavior of teens. Teens who want to fit in among their friends are most especially prone to this. They try to make friends and they get friends as much as possible. Of these friends there are the good ones who give them the knowledge and information you want need or inquire and there are the ones who give them information about not too good things like drug, alcohol, parties, e.t.c. This influential communication between a teen and his/her peer may be directly or indirectly. Directly such as conversations with their friends or indirectly such as listening to classmates discussing of a party which occurred a night before. Then they begin to mention alcohol, drugs and violence obviously from what have experienced they talk about it in a way possible. Then you would like to see how good it is the next weekend you go to that kind of party. If you can not resist such as a temptation you will begin to do harmful deeds that will definitely ha ve adverse results in the future. Let’s not put all the blame on teens and their peers alone. The mass media is also responsible in an understandable way. The media has proven to be a lot damaging than useful in the type of information meant for mature audience but end up with the immature audience. Soap operas and frivolous shows shown on TV contain immoral and untrue images of the world as it is more of the writer’s imagination or the way directors direct them to act. Most teenagers are probably old enough to watch this shows but not mature enough to comprehend with the fictitious nature of movies and soap operas.

Although Protestants

The end of 20th Century saw denominationalism crop up in the church which was eroding the traditions upon which the Christian faith was based. Although Protestants started a good thing, in the end it spurned out of control as many sought to have a denomination that could give them an identity and a sense of purpose in the carrying out the mission of Christianity.Denominationalism has been hailed as an evil thought but ironically it is replacing the religious practices. In the old times, it was associated with ethnic, racial or even class division but with modern times it has evolved to stratification through secularization and education.Sociological analysis is playing a part in disseminating this information because of the way the American society has become polarized especially when it comes to religion (Christianity).Many people have moved from the main stream churches and have found identities in the modern charismatic churches that do not so much revolve around traditions but ar e embracing modern ideologies and secularization. In the old times, people used to stick to one denomination (church) for a lifetime but now things have changed with people switching churches at least once in lifetime.The aspect of denominationalism is a new aspect to me which I thought was a normal thing but its interesting to know that it was based on ethnic or even racial differences in the early days of Christianity. In the advent of modernization, it has evolved to be discrimination based on education, and doctrinal bases and going world wide.Many people join churches without knowing what or why the churches are founded just to get a religious identity. Religion is something that is aimed at bringing and uniting people together and denominationalism may be doing that but the underlying reasons are wrong.The cropping of this practice rose as a result of difficult in maintaining the religious traditions mainly due to the liberal nature of people wanting to embrace their own ident ities and also the conservatives loosing their moral authority towards the 21st century.The important message that this article is putting through is that the divisions in Christianity should not be there in the first place because they contradict the tenets of Christianity. It is a noble idea but bringing people together does not involve segregation of others in order to give a sense of identity to a few people.ConclusionDenominationalism has been portrayed more negative than positive which I do not agree because as the article points out, it gives a sense of identity to different people and there is no way all people can fit in one denomination but that does not call for establishment of many denominations.People do not subscribe to the same doctrinal values and therefore whichever denomination they are comfortable in, it is their right to go there. The idea of denominationalism has been portrayed as a division in the Christianity faith which may be true but I do not agree with it .There is no such thing as the standard way of doing things but somehow things have to be done and as long as they are not contravening the law and are morally right, then they ought to be followed. According to me this is the basis of denominationalism where it is based on the way we perform different religious practices and rites like singing, praying and preaching.This article has merely aroused curiosity about denominationalism and it has not dug in deep to bring tangible evidence of what it has caused in the society and what can be done about it. The article has done it as an overview and therefore it should address the issue in depth and how modern Christians can cope with it in embracing their faith and keeping their identity intact.ReferenceNancy, T. (2000). New Life for Denominationalism. Retrieved   June 2, 2009 from,  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚