A New Approach to Evaluation of University Teaching Considering Heterogeneity of Students’ Preferences

AbstractStudents’ evaluations of teaching are increasingly used by universities to evaluate teaching performance. However, these evaluations are controversial mainly due to fact that students value various aspects of excellent teaching differently. Therefore, in this paper we propose a new approach to student evaluation of university teaching based on data from conjoint analysis. Conjoint analysis is a multivariate technique used to analyze the structure of individuals’ preference. In particular, our approach accounts for different importance students attach to various aspects of teaching. Moreover, it accounts explicitly for heterogeneity arising from student preferences, and incorporates it to form comprehensive teaching evaluation score. We have conducted survey and confirmed applicability and efficiency of the proposed approach

Efeitos da reabilitação precoce no desfecho da reabilitação pós-acidente vascular encefálico (AVE) em mulheres com mais de 65 anos e sua correlação com a gravidade do deficit neurológico inicial

Este trabalho visa examinar os efeitos da reabilitação precoce, a curto e longo prazo, no desfecho do acidente vascular encefálico (AVE) em mulheres com mais de 65 anos; estabelecer a correlação entre o impacto da gravidade do déficit neurológico na predição dos re-sultados do tratamento de Reabilitação e, ainda, investigar a possibilidade do acompanhamento de parâmetros individuais da Medição de Independência Funcional (MIF) na predição do desfecho da reabilitação do AVE. Atualmente, o AVE é a terceira maior causa de mortalidade na população mundial, bem como a maior causa de invalidez permanente. No cenário atual, as doenças cardiovasculares e cerebrovasculares - que antes eram tidas como exclusivas da população masculina – têm afetado também as mulheres. Por outro lado, observamos uma correlação linear entre o envelhecimento e a ocorrência destas doenças. Concluímos que a implantação do método de reabilitação precoce conduz a uma aceleração significativa do processo de tratamento e recuperação após o AVE em mulheres com mais de 65 anos. Concluímos também que certos parâmetros da MIF, por apresentarem o mesmo padrão de evolução, podem ser utilizados na predição da recuperação global do paciente.This study aims at verifying the effects of short- and long-term rehabilitation on the outcome of encephalic vascular accident (EVA) in women older than 65 years; establishing the correlation between the impact of the neurological deficit severity on the prediction of the rehabilitation treatment outcome as well as investigating the possibility of the follow-up of individual parameters at the Functional Independence Measure (FIM) when predicting the EVA rehabilitation outcome. The EVA is currently the third major cause of death in the world’s population, as well as the main cause of permanent disability. In the present scenario, cardiovascular and cerebrovascular diseases, which used to be observed almost exclusively in the male population, now affect the female population as well. On the other hand, we observe a linear correlation between aging and the occurrence of these diseases. We conclude that the implementation of early rehabilitation leads to a significant acceleration in the treatment and recovery process post-EVA in women older than 65 years. We also conclude that certain FIM parameters can be used to predict the patient’s overall recovery, as they present the same evolution pattern

DESIGN AND IMPLEMENTATION OF NON-UNIFORM QUANTIZERS FOR DISCRETE INPUT SAMPLES

This paper describes an algorithm for grayscale image compression based on non-uniform quantizers designed for discrete input samples. Non-uniform quantization is performed in two steps for unit variance, whereas design is done by introducing a discrete variance. The best theoretical and experimental results are obtained for those discrete values of variance which provide the operating range of quantizer located in the vicinity of maximal signal value that can appear on the entrance. The experiment is performed by applying proposed quantizers for compression of standard test grayscale images as a classic example of discrete input source. The proposed fixed non-uniform quantizers, designed for discrete input samples, provide up to 4.93 [dB] higher PSQNR compared to the fixed piecewise uniform quantizers designed for discrete input samples

Hemijska stabilnost dopianog barijum-cerijum-oksida kao elektrolita za gorivne ćelije na bazi oksida u čvrstom stanju

Predmet ovog integralnog istraživanja je ispitivanje uticaja različitih količina Zr4+, Nb5+ i Ta5+ na hemijsku stabilnost, mikrostrukturna i električna svojstva BaCe0.9Y0.1O3–δ kao elektrolita za gorivne ćelije na bazi oksida u čvrstom stanju. Pored toga, izvršeno je poređenje tih materijala sa BaCe1–xInxO3–δ (x= 0.15; 0.20 i 0.25), a korišćene su i dve različite metode sinteze keramičkih prahova: metoda reakcije u čvrstom stanju i metoda samosagorevanja. Neporozni elektroliti su dobijeni sinterovanjem uniaksijalno presovanih keramičkih prahova BaCe0.9Y0.1O3–δ i BaCe0.9–xY0.1MxO3–δ (x= {0.01; 0.03; 0.05}, M= {Zr4+; Nb5+; Ta5+}) na 1550 °C u toku 5 h. S druge strane, BaCe1–xInxO3–δ su sinterovani na znatno nižoj temperaturi (1300 °C), na kojoj je izdvajanje BaO oksida praktično nemoguće, i to predstavlja glavnu prednost In kao dopanta. Električna karakterizacija sinterovanih uzoraka je izvršena elektrohemijskom impedansnom analizom. Ukupna provodljivost, merena u temperaturnom intervalu od 550–750 °C u atmosferi vlažnog vodonika, opadala je sa snižavanjem temperature i sa porastom koncentracije dopanata za BaCe0.9–xY0.1MxO3–δ (M= {Zr4+; Nb5+; Ta5+}), dok je kod BaCe1–xInxO3–δ primećen suprotan trend, ali su provodljivosti u slučaju dopiranja indijumom bile znatno manje. Hemijska stabilnost elektrolita je ispitana izlaganjem uzoraka atmosferi CO2 na 700 °C u toku 5 h. Svi elektroliti BaCe1–xInxO3–δ su bili postojani na uticaj CO2, kod BaCe0.85Y0.1Nb0.05O3–δ i BaCe0.85Y0.1Ta0.05O3–δ je primećena značajna stabilnost, dok je nestabinost ostalih uzoraka bila izraženija što je sadržaj Nb, Ta ili Zr bio manji. Elektrolit sastava BaCe0.75In0.25O3–δ (BCI25) je pokazao optimalna svojstva, pa je odabran za testiranje rada gorivne ćelije. Zahvaljujući velikoj specifičnoj površini praha BCI25, dobijenog metodom samosagorevanja, bilo je moguće njegovo procesiranje elektroforetskom depozicijom u kompaktan elektrolitni sloj od 10 μm. Izlazna snaga ćelije na 700 °C, sastava vodonik/Ni-BCI25//BCI25//La0.8Sr0.2Co0.2Fe0.8O3-BCI25/vazduh, iznosila je ~250 mW/cm2, čime je potvrđena funkcionalnost ovog elektrolita

The influence of synthesis method on properties of Nb doped BaCe0.9Y0.1O3-δ as a proton conducting electrolyte for IT-SOFC

Materials with perovskite structure based on yttrium-doped barium cerate have been widely investigated as proton conducting electrolytes for intermediate-temperature solid oxide fuel cells (IT-SOFC). The main drawback of these materials is stability in CO2 that can be further enhanced by doping with Nb. By the method of auto-combustion (AC) it is possible to synthesize fine ceramic nano-powders compared to classic solid-state route (SS). The aim of this work is to investigate the influence of different synthesis methods on chemical stability and electrical properties of the sintered BaCe0.9Y0.1O3–δ samples doped with various concentrations of Nb. BaCe0.9-xNbxY0.1O3-δ (where x = 0.01, 0.03 and 0.05) powders were synthesized by the AC and SS methods. Much higher specific surface areas were observed for the samples synthesized by the AC method. The dense electrolyte pellets were obtained after sintering of the powders at 1550 ºC for 5 h.The conductivities determined by impedance measurements in temperature range of 550-750 ºC in wet hydrogen medium showed a decreasing trend with increase of Nb content. The samples synthesized by the AC method had a slightly higher conductivities compared to the same compositions obtained by the SS method. The stability in CO2 at 700 ºC for 5 h, determined by X-ray analysis, was enhanced with increase in Nb concentration and there was no significant difference in stability in respect to the synthesis method. It was found that BaCe0.87Nb0.3Y0.1O3-δ is the optimal composition that satisfies the opposite demands for electrical conductivity and chemical stabilty. Its conductivity in wet hydrogen at 650 ºC is 8.7.10-3 Scm-1 which is a bit lower than for undoped BaCe0.9Y0.1O3-δ (1.0.10-2 Scm-1). It was concluded that application of AC method enables synthesis of fine, low-agglomerated nanopowders and further processing that results in better microstructures of the sintered electrolyte samples and consequently higher electrical conductivities

TENSILE TESTING OF MATERIALS AT ELEVATED TEMPERATURES ON A SMALL LABORATORY DEVICE

Machine parts and constructions are often exposed to elevated or high temperatures in their working environment. The mechanical characteristics of metals obtained by tensile testing then change, so it is very important to know their properties under such conditions. Reliable and accurate values of the mechanical characteristics of metals can be obtained by tensile testing on a small laboratory device. By developing a simple and cost-effective module for testing metals at elevated and high temperatures, experimental tests of DC01 steel were performed at temperatures up to 600 °C, and the results were verified with the results available in the literature. The obtained values of the mechanical characteristics of the materials tested on a small laboratory tensile testing device are in accordance with the results obtained on a conventional tensile testing device.Publishe

IL28B Genetic Variations in Patients with Recurrent Herpes Simplex Keratitis

Background and objectives: Recurrent herpes simplex keratitis (HSK) is the most common cause of corneal blindness in the developed world. A relationship between host gene polymorphisms and the recurrence of herpes simplex virus (HSV) infection has previously been proposed. Thus, the aim of this study was to investigate a potential association between the IL28B host genotype and recurrent HSK. Materials and Methods: Eighty patients older than 18 years of age of both genders with a history of recurrent herpes simplex labialis (HSL) were considered for inclusion. Seventy-five of these patients were found to be seropositive for HSV-1 and were subsequently enrolled in the study. Twenty-four of the enrolled patients also had a history of recurrent HSK associated with severe corneal scarring and visual acuity deterioration. Total DNA was isolated from whole blood samples. A single-nucleotide polymorphism (SNP) rs12979860 near the IL28B gene on chromosome 19 was genotyped. Results: A significant association was observed between recurrent HSK and two SNPs of the IL28B genotype (CCrs12979860 and CTrs12979860, p < 0.01). The variation CCrs12979860 showed a significantly greater association with HSK (16 out of 26 patients) compared with CTrs12979860 (8 out of 34 patients). Conclusion: Seropositive individuals with a history of recurrent HSK are likely to have the CC IL28B genotype. This genotype may be related to incomplete control of the infection and more frequent periodical viral shedding along the first nerve branch of the trigeminal ganglion, which clinically manifests as recurrent herpes keratitis. The clinical manifestation of recurrent HSV-1 infection seems to be influenced by polymorphism of the IL28B genotype

Wandering spleen-a possible cause of adrenal ”mass“-case report

Wandering spleen is a very rare clinical condition character-ized by spleen absence in the normal anatomical location in the upper left quadrant of the abdomen and its presence at another location in the abdomen or pelvis. The ectopic spleen is extremely rare in children, where its increased mobility is the result of a congenital disturbance of the fixation for the anterior wall due to the absence or weakness of the supporting ligaments. Wandering spleen is usually asymptomatic, but its torsion is possible, as well as infarction or rupture which demand an urgent diagnosis and surgical treatment. The diagnosis of wandering spleen can easily be overlooked due to low incidence and insufficient clinical experience, which multiplies patient's risk from life-threatening conditions. We present a case of wandering spleen in an 11-year-old girl with acute abdominal pain, which after ultrasound examination raised suspicion on the right adrenal gland tumor. Additional diagnostics verified an ectopic spleen in the right adrenal box, after which the recommended preventive splenopexy was seriously considered. Due to the fixation of the vital spleen in the new position, but also the negative attitude of the parents towards the surgical intervention, clinical monitoring was selected, with exclusion of intense physical activity that carries the risk of traumatization of the spleen. As the girl has been in good health for over 3 years and without symptoms, we consider that the selection of conservative access although difficult, was correct. We hope that our experience in treating wandering spleen in girls will increase the number of valid facts about this rare condition