bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using item response theory to explore the psychometric properties of extended matching questions examination in undergraduate medical education
Authors: Bhakta Bipin , Tennant Alan , Horton Mike , Lawton Gemma , Andrich David 
Published: March 2005

Abstract
Background
As assessment has been shown to direct learning, it is critical that the examinations developed to test clinical competence in medical undergraduates are valid and reliable. The use of extended matching questions (EMQ) has been advocated to overcome some of the criticisms of using multiple-choice questions to test factual and applied knowledge.

Methods
We analysed the results from the Extended Matching Questions Examination taken by 4th year undergraduate medical students in the academic year 2001 to 2002. Rasch analysis was used to examine whether the set of questions used in the examination mapped on to a unidimensional scale, the degree of difficulty of questions within and between the various medical and surgical specialties and the pattern of responses within individual questions to assess the impact of the distractor options.

Results
Analysis of a subset of items and of the full examination demonstrated internal construct validity and the absence of bias on the majority of questions. Three main patterns of response selection were identified.

Conclusion
Modern psychometric methods based upon the work of Rasch provide a useful approach to the calibration and analysis of EMQ undergraduate medical assessments. The approach allows for a formal test of the unidimensionality of the questions and thus the validity of the summed score. Given the metric calibration which follows fit to the model, it also allows for the establishment of items banks to facilitate continuity and equity in exam standards.
Fuzzy species among recombinogenic bacteria
Authors: Hanage William P , Fraser Christophe , Spratt Brian G 
Published: March 2005

Abstract

Background

It is a matter of ongoing debate whether a universal species concept is possible for bacteria. Indeed, it is not clear whether closely related isolates of bacteria typically form discrete genotypic clusters that can be assigned as species. The most challenging test of whether species can be clearly delineated is provided by analysis of large populations of closely-related, highly recombinogenic, bacteria that colonise the same body site. We have used concatenated sequences of seven house-keeping loci from 770 strains of 11 named Neisseria species, and phylogenetic trees, to investigate whether genotypic clusters can be resolved among these recombinogenic bacteria and, if so, the extent to which they correspond to named species.

Results

Alleles at individual loci were widely distributed among the named species but this distorting effect of recombination was largely buffered by using concatenated sequences, which resolved clusters corresponding to the three species most numerous in the sample, N. meningitidis, N. lactamica and N. gonorrhoeae. A few isolates arose from the branch that separated N. meningitidis from N. lactamica leading us to describe these species as 'fuzzy'.

Conclusion

A multilocus approach using large samples of closely related isolates delineates species even in the highly recombinogenic human Neisseria where individual loci are inadequate for the task. This approach should be applied by taxonomists to large samples of other groups of closely-related bacteria, and especially to those where species delineation has historically been difficult, to determine whether genotypic clusters can be delineated, and to guide the definition of species.
Physiological characterisation of a pH- and calcium-dependent sodium uptake mechanism in the freshwater crustacean,Daphnia magna
Authors: Glover Chris N. , Wood Chris M. 
Published: March 2005

SUMMARYDaphnia are highly sensitive to sodium metabolism disruption caused by aquatic acidification and ionoregulatory toxicants, due to their finely balanced ion homeostasis. Nine different water chemistries of varying pH (4, 6 and 8) and calcium concentration (0, 0.5 and 1 mmol l–1) were used to delineate the mechanism of sodium influx in Daphnia magna. Lowering water pH severely inhibited sodium influx when calcium concentration was high, but transport kinetic analysis revealed a stimulated sodium influx capacity (Jmax) when calcium was absent. At low pH increasing water calcium levels decreased Jmax and raised Km (decreased sodium influx affinity), while at high pH the opposite pattern was observed (elevated Jmax and reduced Km). These effects on sodium influx were mirrored by changes in whole body sodium levels. Further examination of the effect of calcium on sodium influx showed a severe inhibition of sodium uptake by 100 μmol l–1 calcium gluconate at both low (50 μmol l–1) and high (1000 μmol l–1) sodium concentrations. At high sodium concentrations,stimulated sodium influx was noted with elevated calcium levels. These results, in addition to data showing amiloride inhibition of sodium influx(Ki=180 μmol l–1), suggest a mechanism of sodium influx in Daphnia magna that involves the electrogenic 2Na+/1H+ exchanger.
Social experience and pheromonal perception can change male–male interactions inDrosophila melanogaster
Authors: Svetec Nicolas , Ferveur Jean-François 
Published: March 2005

SUMMARYSocial interaction with conspecifics can influence the developing brain and behaviour of the exposed animal. This experience can involve the exchange and retention of visual, chemical, acoustic and tactile signals. When several Drosophila melanogaster male flies are associated with mated females in the presence of food, they show frequent aggressive interactions. To measure the role of social experience on male–male interaction, two tester males – naïve or exposed to sibling(s) during a variable period of their adult development – were confronted in the absence of female and food. The two males displayed homosexual courtship and aggressive behaviours, the frequency, intensity and directionality of which varied according to their experience. The effect of social experience was greatly enhanced between transgenic males partially defective for pheromonal perception, indicating that male inhibitory pheromones are normally used to repress male–male interaction.
The role of the mesothoracic spiracles in respiration in flighted and flightless dung beetles
Authors: Duncan Frances D. , Byrne Marcus J. 
Published: March 2005

SUMMARYThe relative role of the mesothoracic and abdominal spiracles in respiration was examined using flow-through respirometry in four dung beetle species from different habitats. Two species of flightless beetles, Scarabaeus (Pachysoma) gariepinus and Scarabaeus (Pachysoma) striatum, from the arid western region of southern Africa and a large flighted species, Pachylomerus femoralis, from a more mesic habitat were compared with Circellium bacchus, a flightless beetle from a low rainfall eastern area. All species showed a form of the discontinuous gas exchange pattern at rest. The mesic flighted species used a closed, flutter, open, cycle (CFO)while those species from more arid habitats used a closed, ventilation, cycle(CV) or a closed, burst cycle (CB). The relative importance of the mesothoracic spiracles in CO2 emission varied between the species,even between those from the same genus and habitat. C. bacchus and P. femoralis represent extremes of CO2 emission from the mesothoracic spiracles; from almost total to almost none, respectively. Overall, mesothoracic CO2 emission and convection were more pronounced in the dry habitat species, supporting the hypothesis that both strategies aid in the reduction of water loss.
Plasma chromogranin A in patients with autoimmune chronic atrophic gastritis, enterochromaffin-like cell lesions and gastric carcinoids
Authors: Peracchi M , Gebbia C , Basilisco G , Quatrini M , Tarantino C , Vescarelli C , Massironi S , Conte D 
Published: March 2005

Objective: In atrophic body gastritis (ABG) chronic hypergastrinaemia stimulates enterochromaffin-like (ECL) cell proliferation with development of cell hyperplasia, dysplasia and possibly type-1 gastric carcinoids. As circulating chromogranin A (CgA) levels are a marker of neuroendocrine tumours, we evaluated the clinical usefulness of CgA assay in ABG patients to detect those with carcinoids.
Design and methods: Plasma CgA levels were measured using a commercial ELISA in 45 healthy volunteers, nine patients with type-1 gastric carcinoids and 43 consecutive ABG patients (21 without and 22 with ECL cell hyperplasia/dysplasia).
Results: CgA levels were significantly higher in ABG patients with and without gastric carcinoids than in healthy subjects (P < 0.001). The highest values occurred in patients with carcinoids (median (interquartile range): 58.1 (44.5–65.3) U/l) and with ECL cell hyperplasia/dysplasia (35.5 (31.8–48.65) U/l) but there were no significant differences in CgA among the various subgroups of ABG patients classified according to ECL cell status. Nevertheless, in ABG patients without carcinoids CgA values correlated with the presence and severity of ECL cell lesions (r
s = 0.428, P < 0.01). The sensitivity and specificity of the CgA assay in identifying patients with carcinoids were 100 and 23% respectively.
Conclusions: CgA plasma levels reflect the histological degree of ECL cell lesions in patients with ABG but the assay specificity is too low to detect among these patients those with gastric carcinoids.
Structure and in vitro antibacterial activity of BuSnCl3−n[(OPPh2)(SPPh2)N]n (n = 1, 2)
Authors: Rotar Adina , Silvestru Anca , Silvestru Cristian , Drake John E. , Hursthouse Michael B. , Light Mark E. , Bunaciu Liana , Bunaciu Petre 
Published: March 2005

AbstractBuSnCl2[(OPPh2)(SPPh2)N] (1) and BuSnCl[(OPPh2)(SPPh2)N]2 (2) were prepared by reacting BuSnCl3 and K[(OPPh2)(SPPh2)N], in 1:1 and 1:2 molar ratios. The compounds were investigated in solution by multinuclear (1H, 13C, 31P, 119Sn) NMR spectroscopy. Variable‐temperature 31P NMR studies indicate dynamic behaviour in solution. The solid‐state molecular structure was established by single‐crystal X‐ray diffraction revealing 5‐ and 6‐coordinated metal atoms in 1 and 2, respectively, as a result of the monometallic biconnective behaviour of the monothioimidodiphosphinato moieties. Preliminary results on the in vitro biological activity are reported. Copyright © 2005 John Wiley & Sons, Ltd.
Image coding usingM‐channel paraunitary filterbanks: Design with regularity and signal extension method
Authors: Oka Tomohiro , Uto Toshiyuki , Ikehara Masaaki 
Published: March 2005

AbstractThis paper proposes a signal extension method to realize image coding byM‐channel paraunitary filter banks and a lattice configuration of the latter satisfying regularity. In the conversion code for finitely long signals such as images, nonextensional convolution is important for efficient coding without increasing the number of coded pixels. To this end, nonextensional convolution is realized in a generalM‐channel filter bank. Also, a signal extension method is proposed using singular value decomposition so that the extended signals are smooth. Next, in theM‐channel paraunitary filter banks, a design method is proposed that is based on the lattice configuration satisfying the first‐order regularity so that the DC leakage is prevented. Finally, the proposed method is applied to coding of various stationary images and the effectiveness of the method is demonstrated. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 88(7): 52–60, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20134
Category recognition system using two ultrasonic sensors and combinational logic circuit
Authors: Moritake Yusuke , Hikawa Hiroomi 
Published: March 2005

AbstractIn this paper, we employ a technique that is used to recognize a material from the reflected ultrasonic waves and propose a category recognition system using two ultrasonic sensors. In this system, the reflected waveforms are handled as two‐dimensional images, and which category an object belongs to is instantaneously recognized by pattern matching to reference data by a combinatorial logic circuit. In this system, combinations of information such as the material, angle, and distance of the object are set as the recognition categories. The pattern matching is carried out by a combinatorial logic circuit created directly from the reference data. The recognition experiments with measured waveform data performed according to the proposed method demonstrated the features of the proposed system and its effectiveness when applied to recognition under specific conditions. With five materials set as the categories, the results show that a recognition rate of nearly 100% was obtained, and high recognition results were obtained for almost all of the materials when the categories were extended to combinations of the material, angle, and distance. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 88(7): 33–42, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20147
Speed improvement of FPGA by mixing multiple‐gate‐width routing switches
Authors: Matsumoto Yohei , Masaki Akira 
Published: March 2005

AbstractIn comparison with ASIC, FPGA is slower in speed and has a smaller logic size that can be integrated. The main cause is the routing switches. Optimization of the gate width of the transistors used is important. Previously, a single gate width has been assumed for all of the path transistors in the optimization. In the present research, a structure is conceived in which multiple gate widths are mixed. The operating speed is increased by about 20% relative to conventional structures. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 88(7): 14–22, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20154
Method to recover lost Internet packets using (n, k, m) convolutional codes
Authors: Arai Masayuki , Yamaguchi Anna , Fukumoto Satoshi , Iwasaki Kazuhiko 
Published: March 2005

AbstractA lost packet recovery method is proposed by using (n, k, m) convolutional codes. The amount of computation in encoding and decoding as well as the lost packet recovery capability are evaluated. In the proposed method, a packet with a length ofqbits is considered as a symbol onGF(2q) for application of the convolutional codes. It is recognized that on the Internet the packet loss position can be identified. Then, decoding is applied to a lossy communications channel on the packet level. First, the procedures for coding and decoding are presented. Subsequently, the packet loss recovery characteristic in the proposed method is analyzed. The condition for recovery of all lost packets is discussed. In the proposed method, linear simultaneous equations can be developed from the generating matrix and the packet loss positions. If these equations have a unique solution, all packet losses can be recovered. Also, by means of the lost packet recovery simulation, the recovery capability and computational complexity of the proposed method are evaluated. Under the model in which packets are independently lost, the method is compared with the packet recovery method using (n, k) Reed–Solomon codes with identicalnandk. Simulation shows that packet recovery by (n, k, m) convolutional codes is effective in the area where the packet loss rate is rather low. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 88(7): 1–13, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20155
Cumulative 5‐year diagnoses of CIN2, CIN3 or cervical cancer after concurrent high‐risk HPV and cytology testing in a primary screening setting
Authors: Hoyer Heike , Scheungraber Cornelia , Kuehne‐Heid Rosemarie , Teller Karin , Greinke Christiane , Leistritz Sabine , Ludwig Beate , Dürst Matthias , Schneider Achim 
Published: March 2005

AbstractThe aim of our study was to assess the cumulative 5‐year diagnoses of CIN2, CIN3 or invasive cervical cancer (CIN2+) after concurrent screening by high‐risk HPV test and Pap smear in a primary screening setting. Four thousand thirty‐four women from Eastern Thuringia/Germany were recruited from 1996 to 1998 for baseline screening that included routine cytology, high‐risk HPV testing by consensus primer PCR GP5+/6+ and routine colposcopy. After a median of 59 months 3,153 women participated in final screening using identical methods. Women with abnormal cytology or colposcopy or a positive high‐risk HPV test at any time during the study period were recalled for expert colposcopy and histologic verification. CIN2+ was detected in 160 women resulting in a cumulative 5‐year proportion of 4.4% (95% CI: 3.7–5.0%). Of 3,702 women who were high‐risk HPV negative at baseline, 34 (1.1–95% CI: 0.7–1.4%) had either prevalent CIN2+ or developed CIN2+ within the observation period. HPV/cytology double negatives at baseline were at lowest risk for CIN2+ (1.0–95% CI: 0.7–1.4%) compared to screening positives (16.8–100% depending on combined test results). The 5‐year negative predictive value in HPV−/Cyto− women was 99.0% (95% CI: 98.6–99.3%). This suggests that a prolongation of the screening intervals in this group is feasible. However, it should be noted that 1 woman developed a microinvasive carcinoma within the observation period. Moreover, 2 women with prevalent cancer were missed by both tests. The prognostic relevance of concurrent high‐risk HPV/cytology screening needs to be verified further by randomized trials. © 2005 Wiley‐Liss, Inc.
Tobacco‐specific nitrosamines in smokeless tobacco products marketed in India
Authors: Stepanov Irina , Hecht Stephen S. , Ramakrishnan Sreevidya , Gupta Prakash C. 
Published: March 2005

AbstractSmokeless tobacco products are a known cause of oral cancer in India. Carcinogenic tobacco‐specific nitrosamines in these products are believed to be at least partially responsible for cancer induction, but there have been no recent analyses of their amounts. We quantified levels of 4 tobacco‐specific nitrosamines, N′‐nitrosonornicotine (NNN), N′‐nitrosoanatabine (NAT), N′‐nitrosoanabasine (NAB) and 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanone (NNK), in 32 products marketed currently in India. Levels of nitrate, nitrite and nicotine were also determined. The highest levels of tobacco‐specific nitrosamines were found in certain brands of khaini, zarda and other smokeless tobacco products. Concentrations of NNN and NNK in these products ranged from 1.74–76.9 and 0.08–28.4 μg/g, respectively. Levels of tobacco‐specific nitrosamines in gutka were generally somewhat lower than in these products, but still considerably higher than nitrosamine levels in food. Tobacco‐specific nitrosamines were rarely detected in supari, which does not contain tobacco, or in tooth powders. The results of our study demonstrate that exposure to substantial amounts of carcinogenic tobacco‐specific nitrosamines through use of smokeless tobacco products remains a major problem in India. © 2005 Wiley‐Liss, Inc.
Chlamydia trachomatis infection and persistence of human papillomavirus
Authors: Silins Ilvars , Ryd Walter , Strand Anders , Wadell Göran , Törnberg Sven , Hansson Bengt Göran , Wang Xiaohong , Arnheim Lisen , Dahl Viktor , Bremell Daniel , Persson Kenneth , Dillner Joakim , Rylander Eva 
Published: March 2005

AbstractHuman papillomavirus (HPV) persistence is the major cause of cervical cancer, but most HPV infections will not persist and risk factors for HPV persistence are not well known. Chlamydia (C.) trachomatis infection seems to also be associated with cervical cancer. We investigated whether C. trachomatis infection is a risk factor for HPV persistence. In a cohort of 12,527 women participating in a population‐based HPV screening trial in Sweden, 6,418 women completed testing for HPV DNA by general primer PCR and typing by reverse dot blot hybridization. On average 19 months later, 303 women that had been HPV‐positive and had normal cytology at enrollment completed a new HPV test. Environmental exposures were assessed by an 87‐item questionnaire. Previous sexually transmitted infections were also investigated by serology. At follow‐up, 44% of the women were positive for the same type of HPV DNA as at enrollment. Persistence correlated with length of follow‐up (p < 0.01) and condom use seemed to protect against HPV persistence (p < 0.05). The most significant risk factor for persistent presence of HPV DNA was self‐reported history of previous C. trachomatis infection (relative risk in multivariate model = 2.09; 95% confidence interval = 1.05–4.18). We conclude that persistence of oncogenic HPV infections is more likely among women with a previous C. trachomatis infection. © 2005 Wiley‐Liss, Inc.
Cytotoxic effects of γδ T cells expanded ex vivo by a third generation bisphosphonate for cancer immunotherapy
Authors: Sato Kiyoshi , Kimura Shinya , Segawa Hidekazu , Yokota Asumi , Matsumoto Seiji , Kuroda Junya , Nogawa Masaki , Yuasa Takeshi , Kiyono Yasushi , Wada Hiromi , Maekawa Taira 
Published: March 2005

AbstractNitrogen containing‐bisphosphonates (N‐BPs), widely used to treat bone diseases, have direct antitumor effects via the inactivation of Ras proteins. In addition to the direct antitumor activities, N‐BPs expand gdγδT cells, which exhibit major histocompatibility complex‐unrestricted lytic activity. BPs accumulate intermediate metabolites which may be tumor antigens in target cells. The purpose of our study was to clarify the cytotoxicity of gdγδ T cells expanded ex vivo by the most potent N‐BP, zoledronate (ZOL). Especially, we focused on the importance of pretreatment against target cells also with ZOL; 1 mμM ZOL plus IL‐2 increased the absolute number of gdγδT cells 298–768 fold for 14 days incubation. The small cell lung cancer and fibrosarcoma cell lines pretreated with 5 mμM ZOL showed a marked increase in sensitivity to lysis by gdγδT cells. While, untreated cell lines were much less sensitive to lysis by gdT cells. Video microscopy clearly demonstrated that gdγδT cells killed target cells pre‐treated with ZOL within 3 hr. Pretreatment with 80 mμg/kg ZOL also significantly enhanced the antitumor activity of gdγδT cells in mice xenografted with SBC‐5 cells. These findings show that ZOL significantly stimulated the proliferation of gdγδT cells and that gdγδT cells required pre‐treatment with ZOL for cytotoxic activity against target cells. © 2005 Wiley‐Liss, Inc.
Hepatitis C infection is not associated with systemic HIV‐associated non‐hodgkin's lymphoma: A cohort study
Authors: Waters Laura , Stebbing Justin , Mandalia Sundhiya , Young Anne Marie , Nelson Mark , Gazzard Brian , Bower Mark 
Published: March 2005

AbstractImmunosuppression induced by the human immunodeficiency virus (HIV) increases the risk of developing non‐Hodgkin's lymphoma (NHL). As the hepatitis C virus (HCV) has been implicated in the development of B cell lymphomas, we compared the incidence of systemic NHL during HIV infection compared to HIV and HCV co‐infection. Of 5,832 individuals studied during the era of highly active anti‐retroviral therapy (HAART), 102 patients were diagnosed with systemic NHL. The incidence of systemic NHL was 6.9 of 104 patient years during HIV infection compared to 7.1 of 104 patient years during HIV alone (p = 0.9). In this immunocompromised patient population, there was no association between HCV infection and an increased risk of lymphoma. © 2005 Wiley‐Liss, Inc.