Previous Answers Research Articles

Notes on electromagnetic waves in a medium with negative ε and μ. II

The consideration of the problem of the possible existence of homogeneous isotropic media with simultaneously negative permittivities and permeabilities is continued. It is shown that the previous negative answer is also retained in the case of a more rigorous consideration of frequency dispersion. As a matter of discussion, it is proposed to somewhat change the system of Maxwell equations in a dispersing medium.

Words of Devotion

Words of Devotion

Memory, Decision-Making, and the Ventromedial Prefrontal Cortex (vmPFC): The Roles of Subcallosal and Posterior Orbitofrontal Cortices in Monitoring and Control Processes.

The ventromedial prefrontal cortex (vmPFC) prominently and separately features in neurobiological models of decision-making (e.g., value-encoding) and of memory (e.g., automatic veracity-monitoring). Recent decision-making models propose value judgments that inherently comprise of second-order confidence estimates. These demonstrate quadratic relationships with first-order judgments and are automatically encoded in vmPFC activity. Memory studies use Quantity-Accuracy Profiles to capture similar first-order and second-order meta-mnemonic processes, suggesting convergence across domains. Patients with PFC damage answered general knowledge questionnaires under 2 conditions. During forcedreport, they chose an answer and rated the probability of it being correct (first-order "monitoring"). During free report, they could choose to volunteer or withhold their previous answers (second-order "control") to maximize performance. We found quadratic relationships between first-order and second-order meta-mnemonic processes; voxel-based lesion-symptom mapping demonstrated that vmPFC damage diminished that relationship. Furthermore, damage to subcallosal vmPFC was specifically associated with impaired monitoring and additional damage to posterior orbitofrontal cortex led to deficient control. In decision-making, these regions typically support valuation and choice, respectively. Persistent spontaneous confabulation (false memory production) confirmed the clinical relevance of these dissociations. Compared with patients with no confabulation history, patients who currently confabulate were impaired on both monitoring and control, whereas former confabulators demonstrated impaired monitoring but intact control.

Caracterização e tendências de gestão dos impactos negativos e positivos do espeleoturismo

As cavernas estão entre os ambientes mais frágeis da superfície terrestre, em função de suas especificidades físicas, atmosféricas e biológicas. Suas características naturais, associadas aos aspectos culturais das comunidades locais, conferem interesse turístico às cavernas. Todavia, o uso turístico das cavernas gera impactos ambientais negativos, sobretudo quando são adotadas técnicas inadequadas de planejamento e gestão. Os impactos negativos são descritos na presente revisão bibliográfica, com indicações de procedimentos de gestão para evitar, reduzir ou eliminar as consequências danosas do espeleoturismo. Os impactos positivos também são apresentados, na perspectiva de obtenção de um espeleoturismo sustentável. As conclusões argumentam que os impactos negativos não devem ser tomados como impedi-mentos para o turismo em cavernas. Conhecer tais impactos é a chave para a obtenção de respostas prévias que permitam a ampliação da sustentabilidade das cavernas turísticas.

Bayesian decision making in human collectives with binary choices.

Here we focus on the description of the mechanisms behind the process of information aggregation and decision making, a basic step to understand emergent phenomena in society, such as trends, information spreading or the wisdom of crowds. In many situations, agents choose between discrete options. We analyze experimental data on binary opinion choices in humans. The data consists of two separate experiments in which humans answer questions with a binary response, where one is correct and the other is incorrect. The questions are answered without and with information on the answers of some previous participants. We find that a Bayesian approach captures the probability of choosing one of the answers. The influence of peers is uncorrelated with the difficulty of the question. The data is inconsistent with Weber’s law, which states that the probability of choosing an option depends on the proportion of previous answers choosing that option and not on the total number of those answers. Last, the present Bayesian model fits reasonably well to the data as compared to some other previously proposed functions although the latter sometime perform slightly better than the Bayesian model. The asset of the present model is the simplicity and mechanistic explanation of the behavior.

Convergence of sequences of inverse limits

We consider the following question. Let X be a compact metric space, and let (fn:X→2X)n=1∞ be a sequence of upper semi-continuous set-valued functions whose graphs converge to the graph of a function f:X→2X in the hyperspace 2X×X. Under what additional assumptions does it follow that the corresponding sequence of inverse limits (lim←fn)n=1∞ converges to lim←f in the hyperspace 2∏i=1∞X?We give two nonequivalent conditions which generalize previous answers given by Banič, Črepnjak, Merhar, and Milutinović in 2010 and 2011.

Surgical Études

BACKGROUND: A challenge to education is offering adequate hands-on learning opportunities to residents without compromising safety. Surgical residents may be able to apply artistic training habits to their residency training. PURPOSE: The first goal is to determine the opinion of surgery residents regarding the degree of attending involvement in difficult procedures. The second goal is to describe the artistic inclinations residents and how this may relate to training techniques in acquiring manual skills. METHODS: An anonymous survey was distributed to 691 UHCMC residents questioning learning preferences, efficacious teaching, and artistic skills. Survey questions were adjusted dependent upon previous answers. RESULTS: 152 residents attempted the survey, of which 22.4% were surgery, 26.3% were some surgical/some medical, and 51.3% were medicine. Of surgery residents, 85.3% agreed that allowing a resident to struggle through a procedure was effective teaching and 75.8% preferred being allowed to struggle. 61.3% of surgery residents felt struggle was effective teaching most or all of the time and 74.2% found struggle to be preferable most or all of the time. 45.2% of residents reported that attendings perform procedures too often for residents, and 45.2% reported that their opinion depended upon the attending. The remaining 9.7% felt attendings perform procedures with appropriate frequency. When asked about artistic inclination, 61.3% of surgical residents agreed that they were artistic. Of these, 89.5% were musical and 73.7% visual; 94.7% felt their artistic training could be of help in residency. A targeted sub-study of plastic surgery residents revealed that 90.9% of residents were artistic, with 72.7% being musical and 72.7% visual; 80% reported this training could be of help in residency. 59.1% of strictly medical residents reported being artistic, of which 76.9% felt this training could be of help in residency. CONCLUSIONS: Allowing a resident to struggle through a difficult procedure is both an efficacious and preferable teaching method from the resident perspective. A majority of surgery residents felt that attendings performed procedures too often. Most residents identify as artistic and believe that their artistic training may help them in their residency training.

Theoretical Repeatability Coefficient of a 100 mm Visual Analog Scale in Children

The aim of this study was to determine the theoretical repeatability coefficient of a 100 mm visual analog scale (VAS) in children in different circumstances. A prospective cohort study was conducted using a convenience sample of patients aged 8 to 17 years presenting to a pediatric emergency department. Patients were asked how they liked a variety of foods (surrogate for stable pain stimulus) on a 100 mm VAS with 4 different sets of questions repeated 3 times: set 1--questions at 3-minute intervals with no specific instructions other than how to complete the VAS; set 2--same format as set 1 except for the duration of the interval (1 min); set 3--same as set 1 except patients were asked to remember their answers; set 4--same as set 1 except patients were shown their previous answers. For each, the repeatability coefficient of the VAS was determined. A total of 100 patients aged 12.1±2.4 years were enrolled. The repeatability coefficient for the questions asked at the 3-minute interval was 12 mm, whereas it was 8 mm when asked at the 1-minute interval. When asked to remember their previous answers or to reproduce them, the repeatability coefficients for the questions were 7 and 6 mm, respectively. The conditions of the assessments influence the repeatability coefficient of the VAS. Depending on different circumstances, the repeatability coefficient in children aged 8 to 17 years varies from 6 to 12 mm on a 100 mm VAS.

PTH-024 Self Provided Guided Medical History Is Fast, Complete And Accurate

IntroductionThe medical history is the fundamental basis of diagnosis. Every medical student learns how to take a full history, but in clinical practice the history is often truncated due to...

Search problems in vector spaces

We consider the following $q$-analog of the basic combinatorial search problem: let $q$ be a prime power and $\GF(q)$ the finite field of $q$ elements. Let $V$ denote an $n$-dimensional vector space over $\GF(q)$ and let $\mathbf{v}$ be an unknown 1-dimensional subspace of $V$. We will be interested in determining the minimum number of queries that is needed to find $\mathbf{v}$ provided all queries are subspaces of $V$ and the answer to a query $U$ is YES if $\mathbf{v} \leqslant U$ and NO if $\mathbf{v} \not\leqslant U$. This number will be denoted by $A(n,q)$ in the adaptive case (when for each queries answers are obtained immediately and later queries might depend on previous answers) and $M(n,q)$ in the non-adaptive case (when all queries must be made in advance). In the case $n=3$ we prove $2q-1=A(3,q)<M(3,q)$ if $q$ is large enough. While for general values of $n$ and $q$ we establish the bounds \[ n\log q \le A(n,q) \le (1+o(1))nq \] and \[ (1-o(1))nq \le M(n,q) \le 2nq, \] provided $q$ tends to infinity.

MODEL-THEORETIC PROPERTIES OF ULTRAFILTERS BUILT BY INDEPENDENT FAMILIES OF FUNCTIONS

Abstract Our results in this paper increase the model-theoretic precision of a widely used method for building ultrafilters, and so advance the general problem of constructing ultrafilters whose ultrapowers have a precise degree of saturation. We begin by showing that any flexible regular ultrafilter makes the product of an unbounded sequence of finite cardinals large, thus saturating any stable theory. We then prove directly that a “bottleneck” in the inductive construction of a regular ultrafilter on λ (i.e., a point after which all antichains of ${\cal P}\left( \lambda \right)/{\cal D}$ have cardinality less than λ) essentially prevents any subsequent ultrafilter from being flexible, thus from saturating any nonlow theory. The constructions are as follows. First, we construct a regular filter ${\cal D}$ on λ so that any ultrafilter extending ${\cal D}$ fails to ${\lambda ^ + }$ -saturate ultrapowers of the random graph, thus of any unstable theory. The proof constructs the omitted random graph type directly. Second, assuming existence of a measurable cardinal κ, we construct a regular ultrafilter on $\lambda &amp;gt; \kappa$ which is λ-flexible but not ${\kappa ^{ + + }}$ -good, improving our previous answer to a question raised in Dow (1985). Third, assuming a weakly compact cardinal κ, we construct an ultrafilter to show that ${\rm{lcf}}\left( {{\aleph _0}} \right)$ may be small while all symmetric cuts of cofinality κ are realized. Thus certain families of precuts may be realized while still failing to saturate any unstable theory.

The effects of age and delay on responses to repeated questions in forensic interviews with children alleging sexual abuse.

We examined transcripts of forensic interviews with 115 children aged between 3 and 12 years, interviewed between 1 day and 18 months after allegedly experiencing a single incident of sexual abuse. Repeated questions were categorized with respect to the reasons why interviewers asked questions again, how interviewers asked repeated questions, and how children responded. On average, interviewers asked 3 repeated questions per interview. As age increased, the frequency of question repetition declined but there was no association between repetition and delay. Interviewers most often repeated questions for clarification (53.1%), but questions were also repeated frequently to challenge children's previous responses (23.7%), and for no apparent reason (20.1%). In response, children typically repeated (54.1%) or elaborated on (31.5%) their previous answers; they contradicted themselves less often (10.8%). Questions repeated using suggestive prompts were more likely to elicit contradictions. There was no association between age or delay and the reasons why questions were repeated, how they were repeated, and how children responded. These findings emphasize the importance of training forensic interviewers to repeat questions only when the children or interviewers seek clarification and to encourage children who are anxious or reluctant to disclose. All repeated questions should be open-ended and interviewers should explain to children why questions are being repeated.

Reply to criticism of the ‘Orch OR qubit’ – ‘Orchestrated objective reduction’ is scientifically justified

The critical commentary by Reimers et al. [1] regarding the Penrose–Hameroff theory of ‘orchestrated objective reduction’ (‘Orch OR’) is largely uninformed and basically incorrect, as they solely criticize non-existent features of Orch OR, and ignore (1) actual Orch OR features, (2) supportive evidence, and (3) previous answers to their objections (Section 5.6 in our review [2]). Here we respond point-by-point to the issues they raise.

THU0472-HPR Calibration of a multidimensional item bank to measure fatigue in rheumatoid arthritis patients

BackgroundFrequently used questionnaires to measure fatigue in rheumatoid arthritis (RA) are not developed from the patients’ perspective or have a fixed-length format. Modern psychometrics provide the possibility to measure patient...

OP0097-HPR The Challenge to Develop a Multidimensional Computerized Adaptive Test for Fatigue in Rheumatoid Arthritis

BackgroundComputerized adaptive testing (CAT) provides the possibility to measure patient reported outcomes precisely at an individual level. As items are selected based on the previous answer of a patient, the...

Why Community College Students are so Poor, but Only 16.9% Received Federal Pell Grants

Community colleges have maintained a mission and commitment to open access. Likewise, Federal Pell Grants have historically served as a primary means for low income populations to afford higher education. Thus, community college students and Federal Pell Grants are important parts of the American higher education landscape and a mode of social and individual transformation (Baime & Mullin, 2011). In 2006, Romano and Millard asked the question, “If community college students are so poor, why do only 16.9% of them receive Pell Grants?” The authors put forth the question to financial aid professionals and based on their responses posited seven possible answers. The purpose of this paper is to expand on some of the previous answers and provide the following additional explanations: (a) lack of information; (b) verification; (c) financial aid office's workload; and (d) student employment. Romano and Millard (2006) concluded Federal Pell Grant rate cannot be used to determine low income at community colleges. When considering this new information, a zero expected family contribution (EFC) is suggested to be used when awarding institutional and state need-based aid, which would ensure funding to the lowest income students. When a zero EFC is used to define low income, data shows there are more low income community college students than their four-year counterparts. This does not negate the fact that many of the aforementioned issues are salient and important for community college students, but depending on how low income is defined determines a critical aspect of why community college students are so poor.

Computerized Adaptive Testing for Public Opinion Surveys

Survey researchers avoid using large multi-item scales to measure latent traits due to both the financial costs and the risk of driving up nonresponse rates. Typically, investigators select a subset of available scale items rather than asking the full battery. Reduced batteries, however, can sharply reduce measurement precision and introduce bias. In this article, we present computerized adaptive testing (CAT) as a method for minimizing the number of questions each respondent must answer while preserving measurement accuracy and precision. CAT algorithms respond to individuals' previous answers to select subsequent questions that most efficiently reveal respondents' positions on a latent dimension. We introduce the basic stages of a CAT algorithm and present the details for one approach to item selection appropriate for public opinion research. We then demonstrate the advantages of CAT via simulation and empirically comparing dynamic and static measures of political knowledge.

Evidence‐based guideline for the written radiology report: Methods, recommendations and implementation challenges

The written radiology report is the dominant method by which radiologists communicate the results of diagnostic and interventional imaging procedures. It has an important impact on decisions about further investigation and management. Its form and content can be influential in reducing harm to patients and mitigating risk for practitioners but varies markedly with little standardisation in practice. Until now, the Royal Australian and New Zealand College of Radiologists has not had a guideline for the written report. International guidelines on this subject are not evidence based and lack description of development methods. The current guideline seeks to improve the quality of the written report by providing evidence-based recommendations for good practice. The following attributes of the report are addressed by recommendations: Content Clinical information available to the radiologist at the time the report was created Technical details of the procedure Examination quality and limitations Findings (both normal and abnormal) Comparison with previous studies Pathophysiological diagnosis Differential diagnoses Clinical correlation and/or answer to the clinical question Recommendations, particularly for further imaging and other investigations Conclusion/opinion/impression Format Length Format Language Confidence and certainty Clarity Readability Accuracy Communication of discrepancies between an original verbal or written report and the final report Proofreading/editing of own and trainee reports.

Learning strategies of medical students in the surgery department, Jeddah, Saudi Arabia

ObjectivesTo identify medical students’ perceptions of their learning strategies including, learning habits, resources, and preferred teaching methods, in the Department of Surgery (DOS) of the King Abdulaziz University-Faculty of Medicine (KAU-FoM), in Jeddah, Saudi Arabia.MethodsA cross-sectional descriptive study which was designed to identify students’ perceptions of their learning in the DOS of the KAU-FoM. A questionnaire was administered to a random group of 549 medical students, to explore student perceptions of their learning strategies including methods of learning and learning resources.ResultsThe majority believed that clinical session attendance is always important compared with lectures (88.9% vs 21.9%). Nevertheless, clinical sessions were selected as the third source of learning after learning from assigned textbooks and previous examination model answers. The majority (74.1%) believed that self-instruction at home is the preferred method of learning.ConclusionStudent perspectives should be taken into consideration prior to any future reforms of curriculum. Reforms should adopt a “think globally; act locally” educational strategy based on learner needs.

The ABR “Recalls” Conundrum: An Ethical Quandary

THE SEMANTIC STORM The storm descended upon the radiology community suddenly, unexpectedly, and with ferocity. It was not a storm of rain and heavy winds, but rather a storm of semantics—varying and perhaps conflicting definitions of such words and phrases such as group studying, examination preparation, attestation forms, memorizing questions, recalls, cheating, illegal, and ethics. The storm began on January 13, 2012, when television’s CNN broadcast an “expose” titled “Prescription for Cheating.” The report focused on a radiology resident at a Texas Army hospital who claimed that he failed the ABR’s written examination because he had refused to “cheat” by reviewing previous ABR questions and answers (“recalls”) that were available in an extensive military database. CNN investigators showed portions of the database, which contained a large number of previously—and apparently currently— asked ABR questions and answers. In an interview with a CNN correspondent, ABR Executive Director Gary Becker, MD, agreed that use of such recalls constituted cheating. CNN investigators also reported having attended the 2011 annual meeting of the RSNA, interviewing residents and practicing radiologists who “confirmed that recalls have been widely used in most, if not all, radiology programs for more than a decade” [1]. Although the storm did not wreak physical damage, it did set off an avalanche of emotional and highly opinionated e-mail correspondences, crisscrossing in cyberspace among radiologists all over the nation, as well as follow-up reports from such Web-based entities as Aunt Minnie and MedPage. The Web reports contained quotations from numerous practicing radiologists, radiology residents, and nonradiologists. Becker was quoted as saying, “Studying from the bank of past questions, or relying on the recalls is inappropriate, unnecessary, intolerable, and illegal” [2]. In the same report, the director for communications for the American Board for Family Medicine asserted that its board “has never been concerned about students memorizing old questions on their own.” The president and CEO of the American Board of Medical Specialties stated, “Aside from the radiology residents and the more than 100 internal medicine residents who got suspended in 2010 for giving test answers to an exam review company, I don’t know of any other cheating happening in any of the Boards” [2].