Chi-square and Poissonian Data: Biases Even in the High-Count Regime and How to Avoid them

We demonstrate that two approximations to the chi^2 statistic as popularly employed by observational astronomers for fitting Poisson-distributed data can give rise to intrinsically biased model parameter estimates, even in the high counts regime, unless care is taken over the parameterization of the problem. For a small number of problems, previous studies have shown that the fractional bias introduced by these approximations is often small when the counts are high. However, we show that for a broad class of problem, unless the number of data bins is far smaller than \sqrt{N_c}, where N_c is the total number of counts in the dataset, the bias will still likely be comparable to, or even exceed, the statistical error. Conversely, we find that fits using Cash's C-statistic give comparatively unbiased parameter estimates when the counts are high. Taking into account their well-known problems in the low count regime, we conclude that these approximate chi^2 methods should not routinely be used for fitting an arbitrary, parameterized model to Poisson-distributed data, irrespective of the number of counts per bin, and instead the C-statistic should be adopted. We discuss several practical aspects of using the C-statistic in modelling real data. We illustrate the bias for two specific problems, measuring the count-rate from a lightcurve and obtaining the temperature of a thermal plasma from its X-ray spectrum measured with the Chandra X-ray observatory. In the context of X-ray astronomy, we argue the bias could give rise to systematically mis-calibrated satellites and a ~5-10% shift in galaxy cluster scaling relations.Comment: 9 pages, 2 figures. Accepted for publication in the Astrophysical Journa

Karaman il merkezinde bir gıda sektöründe çalışanların AİDS konusunda bilgi düzeylerinin incelenmesi

According to new data in the UNAIDS 2006 Report, An estimated 38.6 million people are living with HIV worldwide. Approximately 4.1 million people became newly infected with HIV, while approximately 2.8 million people died of AIDS-related illnesses in 2005. HIV/AIDS has increasingly an important. One from most effectual methods in AIDS fight is instructed about risk on behaviors. Education needs about AIDS must be decided to decrease newly infected with HIV. This study was planned to assess level of knowledge and to determinate for education needs related HIV in adults male and female. The study is descriptive type. It was done in a food sector in Karaman city center submitting for research. in May 2006, all of working in the food factory’s administration department  (n=60) has answered the question form preparing by researchers. Participant’s characteristics: 71.7 percent were male, 59.7 percent were university graduate, 75 percent were married. They have been worked over and forty hours in week. All of them have health insurance. Participants had been informed with AIDS percent 65.3 by media such as television, radio, newspaper and percent 10.8 by health professionals. The mean point of their knowledge was 15.35±4.07. 99.9 percent of participants had correctly answered to question that were infected by people whose blood contemned with HIV. 75.8 percent of participants can not correctly answer to question about possibility infected of HIV to be bitten by mosquito or insect. 41.7 percent of participants had answered to question that “what do you do to learn whether your sexual partner infected with HIV or not”, but 59.3 percent of them had not answered same question. Participants answering to this question signed that 98.3 percent of participants have been made by health setting blood test on partner, 12.3 percent of participants will have to observe of disease symptom on partner or health report taken by health setting for his/her partner. 1.7 percent of participants had signed so that they can promote own health using condom during coitus. Knowledge point about AIDS was difference and meaningful by statistical on university graduate of participants more than primary and secondary school graduate of participants. Media establishments should be publishing many programs with AIDS. The health professionals must be instructing to public with AIDS.WHO 2006 verilerine göre; HIV ile yaşayan 38,6 milyon insanın 4,1 milyonu 2005 yılında HIV ile enfekte olmuştur. 2005 yılına kadar 2,8 milyon insan AİDS nedeniyle yaşamını yitirmiştir. HIV/AİDS gittikçe artan bir öneme sahiptir. Mücadelede en etkin yöntemlerden biri riskli davranışları önlemeye yönelik olarak eğitim vermektir. Bunu sağlamak için de eğitim gereksinimleri belirlenmelidir. Bu çalışmada erişkin kadın ve erkeklere verilecek eğitimlerde, gereksinimleri belirlemek ve bilgi düzeylerini değerlendirmek amacıyla planlandı Tanımlayıcı tipteki bu çalışma Karaman il merkezinde araştırmanın yapılmasını kabul eden bir gıda fabrikasında gerçekleştirildi. Fabrikada çalışan idari personelin tümüne (n=60) Mayıs 2006 tarihinde araştırmacılar tarafından hazırlanan soru formları uygulandı. Araştırmaya katılan kişilerin % 71,7’si erkek, %59,7’si üniversite mezunu, %75’i evli, ve %98,1’i haftada 40 saat ve üzerinde çalışmaktadır. Çalışmaya katılan tüm personelin sosyal güvencesi bulunmaktadır. AIDS konusunda %65,3’ü kitle iletişim araçlarından, %10,8’i sağlık personelinden bilgi almıştır. Katılımcıların bilgi puan ortalamaları 15,35±4.07’dir. Katılımcıların %99,9’u başkasından alınan kan ile HIV/AİDS bulaşabileceği sorusuna doğru yanıt; %75,8’i sivrisinek ve böcek ısırması ile HIV/AİDS bulaşabileceğini belirterek yanlış yanıt vermişlerdir. Katılımcıların % 41,7’si, cinsel birliktelik kurdukları kişinin HIV/AİDS olup olmadığını öğrenmek için ne yaparsınız sorusuna yanıt vermişken, %59,3’ü düşüncesini belirtmemiştir. Bu soruyu yanıtlayanların %98,3’ü test yaptırırım derken; %12,3’ü hastalık belirtilerinin gözlenmesi gerektiğini ve sağlık raporu istenebileceğini belirtmiştir. Katılımcıların % 1,7’si prezervatif kullanarak korunabileceklerini ifade etmiştir. Üniversite mezunu olanların diğer mezunlara göre AIDS konusunda bilgi puanları istatistiksel olarak farklı ve anlamlıdır. Medya kuruluşları AIDS ile ilgili programları daha fazla yayınlamalıdır. Sağlık profesyonelleri toplumu AIDS’le ilgili eğitmelidir

Rights Over Natural Resources: the Indonesian Experience

The coassembly of well-defined biological nanostructures relies on a delicate balance between attractive and repulsive interactions between biomolecular building blocks. Viral capsids are a prototypical example, where coat proteins exhibit not only self-interactions but also interact with the cargo they encapsulate. In nature, the balance between antagonistic and synergistic interactions has evolved to avoid kinetic trapping and polymorphism. To date, it has remained a major challenge to experimentally disentangle the complex kinetic reaction pathways that underlie successful coassembly of biomolecular building blocks in a noninvasive approach with high temporal resolution. Here we show how macromolecular force sensors, acting as a genome proxy, allow us to probe the pathways through which a viromimetic protein forms capsids. We uncover the complex multistage process of capsid assembly, which involves recruitment and complexation, followed by allosteric growth of the proteinaceous coat. Under certain conditions, the single-genome particles condense into capsids containing multiple copies of the template. Finally, we derive a theoretical model that quantitatively describes the kinetics of recruitment and growth. These results shed new light on the origins of the pathway complexity in biomolecular coassembly

Personalizing Interactions with Information Systems

Personalization constitutes the mechanisms and technologies necessary to customize information access to the end-user. It can be defined as the automatic adjustment of information content, structure, and presentation tailored to the individual. In this chapter, we study personalization from the viewpoint of personalizing interaction. The survey covers mechanisms for information-finding on the web, advanced information retrieval systems, dialog-based applications, and mobile access paradigms. Specific emphasis is placed on studying how users interact with an information system and how the system can encourage and foster interaction. This helps bring out the role of the personalization system as a facilitator which reconciles the user’s mental model with the underlying information system’s organization. Three tiers of personalization systems are presented, paying careful attention to interaction considerations. These tiers show how progressive levels of sophistication in interaction can be achieved. The chapter also surveys systems support technologies and niche application domains

Huzurevinde çalışan bakım personelinin yaşlılara karşı tutum ve ayrımcılık düzeyleri

WOS:000448434300018Introduction: Rapid increase in the older persons population and accompanyingsociodemographic changes result in family caregiving problems, thereby impelling the olderpersons and their family to opt for nursing care institutions. Because of insufficient nursesworking in nursing homes, healthcare assistants usually care for the older persons. This studyassessed the attitudes of healthcare assistants toward the older persons and ageism.Materials and Method: This descriptive study assessed the attitudes of 108 healthcareassistants working in a public nursing home using Kogan’s Attitudes Toward Older People(KAOP) scale and Ageism Attitude Scale (AAS).Results: The mean age of the 108 healthcare assistants was 40.17.7 years. These individualsare 58.3% male, 85% are married and 62% are primary school graduates. The mean durationof employment of the participants at the nursing home was 80.156.9 months, and 91.7% hadcaregiving certificates. Participants had positive attitudes based on their total KAOP and AASscores and sub-dimension AAS scores. KAOP scores varied according to sex and living withan older persons from the family, whereas AAS scores varied according to sex, income status,living with an older persons from the family, considering training for senior care a necessity,and educational background. According to hierarchical regression analysis for determining thevariability of the total AAS score, Model 1 (sociodemographic variables) predicted 25.6% andModel 2 (sociodemographic, caregiving certificate, duration of employment) predicted 28.4%of the AAS scores.Conclusion: Attitudes of healthcare assistants toward the older persons and ageism arepositive. Educational background, gender, and income level are predictive variables for ageism.Giriş: Yaşlı nüfusun artışı ve buna eşlik eden sosyo-demografik değişimler, ailede bakım sorunlarının yaşanmasına ve kurum bakımının yaşlı birey ve aileleri tarafından tercih edilmesine neden olmaktadır. Yaşlı için ilk kez karşılaştığı bir ortam olan huzurevinde bakım personelinin yaşlılara ve yaşlı ayrımcılığına karşı tutumları yaşlının kurum bakımına uyumu açısından önemlidir. Huzurevlerinde çalışan hemşire sayısının yetersizliği nedeniyle yaşlı bakımını bakım personeli yürütmektedir. Bu çalışma bakım personelinin yaşlılara ve yaşlı ayrımcılığına ilişkin tutumlarını belirlemek amacıyla yapılmıştır. Gereç ve Yöntem: Kamuya ait bir huzurevinde çalışan 108 bakım personelinin yaşlılara ve yaşlı ayrımcılığına yönelik tutumlarını belirlemek amacıyla yaşlılara karşı tutum ve yaşlı ayrımcılığı ölçekleri kullanılarak yapılan tanımlayıcı bir araştırmadır. Bulgular: Araştırmaya katılan bakım personelinin yaş ortalaması 40.1±7.7 olarak bulunmuştur. Bu bireylerin %58.3’ü erkek, %85’i evli, %62’si ilköğretim mezunudur. Bakım personelinin huzurevinde çalışma süre ortalaması 80.1±56.9 aydır ve %91.7’sinin yaşlı bakım sertifikası vardır. Katılımcıların yaşlılara karşı tutum, yaşlı ayrımcılığı ölçekleri ve alt boyutlarından alınan puanlara göre tutumlarının olumlu olduğu bulunmuştur. Yaşlılara karşı tutum ve yaşlı ayrımcılığı ölçekleri puanları cinsiyet, aileden bir yaşlı ile yaşama durumuna; Yaşlı ayrımcılığı ölçeği puanları cinsiyet, gelir durumu, aileden bir yaşlı ile yaşama, yaşlı bakımı eğitiminin gerekliliğini düşünme ve eğitim durumuna göre farklılaşmaktadır. Hiyerarşik regresyon analizi sonuçlarına göre; yaşlı ayrımcılığı ölçek toplam puanının değişkenliğinin belirlenmesinde Model 1’in (sosyodemografik değişkenler) % 25.6 ve Model 2’nin (sosyodemografik, bakım sertifikası ve çalışma süresi değişkenleri) % 28.4 yordayıcı olduğu bulunmuştur. Sonuç: Sonuç olarak bakım personelinin yaşlılara ve yaşlı ayrımcılığına yönelik tutumları olumlu yöndedir. Ayrımcılık değişkeni için cinsiyet, eğitim ve gelir düzeyi yordayıcı değişkenlerdendir

Optical biometry of the anterior segment of the eye: Clinical applications

[No abstract available

Nanoscale force sensors to study supramolecular systems

Supramolecular systems are solutions, suspensions or solids, formed by physical and non-covalent interactions. These weak and dynamic bonds drive molecular self-assembly in nature, leading to formation of complex ordered structures in high precision. Understanding self-assembly and co-assembly is crucial to unravel and mimic many processes occurring in nature. However, the challenge cannot be easily addressed especially in biological systems as it involves many dynamic interactions which may cooperatively, noncooperatively or competitively generate a complex manifold of interaction pathways. In this thesis, we employed two techniques to understand these complex interactions in various supramolecular systems at the nanoscale 1) multiple particle tracking microrheology to study thermoreversible assembly of triple helices in a collagen-inspired recombinant polypeptide in the form of a triblock copolymer gel former; and 2) polyfluorene-based conjugated polyelctrolyte mechosensors to monitor electrostatic co-assembly dynamics of (i) a recombinant diblock copolypeptide which encapsulates the conjugated polyelectrolyte like a protein capsid and (ii) various synthetic diblock copolymers which forms complex coacervate micelles; and finally the orthogonal self-assembly dynamics of (iii) a recombinant viral coat protein which mimics natural rod-like viruses. These novel polymeric mechanosensors work as versatile, non-invasive tools to detect even low degrees of analyte binding or complex formation due to the stress applied on their conjugated backbone. This mechanical stress causes the polymeric backbone to stretch which can be detected by a shift in its fluorescence spectra. </p