A Longitudinal Study on Campylobacter in Conventionally Reared Commercial Broiler Flocks in the United States: Prevalence and Genetic Diversity.

Poultry meat contaminated with Campylobacter, a major bacterial cause of foodborne gastroenteritis worldwide, is considered the primary source of human campylobacteriosis. Thus, reduction or elimination of Campylobacter in poultry production will have a significant impact on food safety and public health. Despite the significant progress made over the last decades, many puzzles remain about the epidemiology of Campylobacter on poultry farms, hampering the development of an effective control strategy. This longitudinal study was conducted to determine the prevalence and genetic diversity of Campylobacter in a U.S. commercial broiler production farm system. Cecal contents (15 samples/flock) and boot swabs (3 samples/flock) were collected from approximately 6-wk-old birds from 406 conventional broiler flocks reared in 53 houses on 15 farms (located within a relatively close geographic proximity and managed by the same poultry integrator) for up to eight consecutive production cycles and cultured for Campylobacter. Pulsed-field gel electrophoresis was used to investigate the genetic diversity of the Campylobacter jejuni isolates recovered from the cecal contents. The prevalence of Campylobacter at the farm, house, and flock levels were found to be 93% (14/15), 79% (42/53), and 47% (192/406), respectively. Campylobacter prevalence varied remarkably among different farms and flocks, with some farms or houses testing consistently negative while others being positive all the time over the entire study period. Campylobacter isolation rate changed significantly by sample type (higher by cecal contents vs. boot swabs) and season/production cycle (higher in spring vs. other seasons). The majority (88%; 2364/2675) of the isolates were identified as C. jejuni, and almost all the rest (11%; 303/2675) were Campylobacter coli. Genotyping showed limited diversity within a flock and suggested persistence of some C. jejuni clones over multiple production cycles on the same farm. In conclusion, this study indicated that although Campylobacter prevalence was overall high, there were marked differences in the prevalence among the broiler flocks or farms tested. Future studies aimed at identification of potential risk factors associated with differential Campylobacter status are warranted in order to develop effective on-farm interventions.

Estudio longitudinal sobre Campylobacter en parvadas comerciales de pollo de engorde criados convencionalmente en los Estados Unidos: prevalencia y diversidad genética. Los productos cárnicos de origen avícola contaminado con Campylobacter, que es una importante causa bacteriana de gastroenteritis transmitida por alimentos en todo el mundo, se consideran la principal fuente de campilobacteriosis humana. Por lo tanto, la reducción o eliminación de Campylobacter en la producción avícola tendrá un impacto significativo en la seguridad alimentaria y en la salud pública. A pesar de los importantes avances realizados en las últimas décadas, persisten muchos enigmas sobre la epidemiología de Campylobacter en las granjas avícolas, lo que obstaculiza el desarrollo de una estrategia de control eficaz. Este estudio longitudinal se realizó para determinar la prevalencia y la diversidad genética de Campylobacter en un sistema de granja de producción comercial de pollos de engorde en los Estados Unidos. Se recogieron contenidos cecales (15 muestras/parvada) y cubre botas de arrastre (tres muestras/parvada) de aves de aproximadamente seis semanas de edad de 406 parvadas de pollos de engorde convencionales criadas en 53 casetas de 15 granjas (ubicadas dentro de una proximidad geográfica relativamente cercana y manejadas por el mismo integrador avícola) durante ocho ciclos de producción consecutivos y con cultivo para Campylobacter. Se utilizó electroforesis en gel de campo con pulsasiones para investigar la diversidad genética de los aislados de Campylobacter jejuni recuperados del contenido cecal. Se encontró que la prevalencia de Campylobacter a nivel de granja, caseta y parvada era del 93% (14/15), 79% (42/53) y 47% (192/406), respectivamente. La prevalencia de Campylobacter varió notablemente entre diferentes granjas y rebaños, y algunas granjas o casetas dieron resultados consistentemente negativos mientras que otras dieron positivo todo el tiempo durante todo el período del estudio. La tasa de aislamiento de Campylobacter cambió significativamente según el tipo de muestra (mayor con muestras de contenido cecal en comparación con los cubre botas de arrastre) y la estación/ciclo de producción (mayor en primavera frente a otras estaciones). La mayoría (88%; 2364/2675) de los aislados se identificaron como C. jejuni, y casi todo el resto (11%; 303/2675) fueron Campylobacter coli. La genotipificación mostró una diversidad limitada dentro de una parvada y sugirió la persistencia de algunos clones de C. jejuni durante múltiples ciclos de producción en la misma granja. En conclusión, este estudio indicó que, aunque la prevalencia de Campylobacter fue alta en general, hubo marcadas diferencias en la prevalencia entre las parvadas o granjas de pollos de engorde analizadas. Se justifica la conducción de estudios futuros destinados a identificar posibles factores de riesgo asociados con el estado diferencial de Campylobacter para desarrollar intervenciones efectivas en las granjas.

Experimental and theoretical insights of functionalized hexavanadates on Na+/K+-ATPase activity; molecular interaction field, ab initio calculations and in vitro assays.

The influence of three functionalized hexavanadates (V6): Na2 [V6O13{(OCH2)3CCH3}2], [H2]2 [V6O13{(OCH2)3CCH2OCOCH2CH3}2] and [(C4H9)4N]2 [V6O13{(OCH2)3CCH2OOC(CH3)2-COOH}2 on Na+/K+-ATPase activity, was investigated in vitro. Including compounds already tested by Xu et al. (Journal of Inorganic Biochemistry 161 (2016) 27-36), all functionalized hexavanadates inhibit the activity of Na+/K+-ATPase in a dose-dependent manner but with different inhibitory potencies. Na2 [V6O13{(OCH2)3CCH3}2] was found to have the best inhibition properties - showing 50% inhibition IC50 = 5.50 × 10-5 M, while [(C4H9)4N]2 [V6O13{(OCH2)3CCH2OOC(CH3)2-COOH}2] showed the lowest inhibitory power, IC50 = 1.31 × 10-4 M. In order to understand the bioactivity of functionalized hexavanadates series, we have also used a combined theoretical approach: determination of electrostatic potential from ab initio theoretical calculations and computation of the molecular interaction field (MIF) surface.

Effects of Resolution, Range, and Image Contrast on Target Acquisition Performance.

OBJECTIVE: We sought to determine the joint influence of resolution, target range, and image contrast on the detection and identification of targets in simulated naturalistic scenes. BACKGROUND: Resolution requirements for target acquisition have been developed based on threshold values obtained using imaging systems, when target range was fixed, and image characteristics were determined by the system. Subsequent work has examined the influence of factors like target range and image contrast on target acquisition. METHOD: We varied the resolution and contrast of static images in two experiments. Participants (soldiers) decided whether a human target was located in the scene (detection task) or whether a target was friendly or hostile (identification task). Target range was also varied (50-400 m). In Experiment 1, 30 participants saw color images with a single target exemplar. In Experiment 2, another 30 participants saw monochrome images containing different target exemplars. RESULTS: The effects of target range and image contrast were qualitatively different above and below 6 pixels per meter of target for both tasks in both experiments. CONCLUSION: Target detection and identification performance were a joint function of image resolution, range, and contrast for both color and monochrome images. APPLICATION: The beneficial effects of increasing resolution for target acquisition performance are greater for closer (larger) targets.

Reactivity of 12-tungstophosphoric acid and its inhibitor potency toward Na+/K+-ATPase: A combined 31P NMR study, ab initio calculations and crystallographic analysis.

Influence of 12-tungstophosphoric acid (WPA) on conversion of adenosine triphosphate (ATP) to adenosine diphosphate (ADP) in the presence of Na+/K+-ATPase was monitored by 31P NMR spectroscopy. It was shown that WPA exhibits inhibitory effect on Na+/K+-ATPase activity. In order to study WPA reactivity and intermolecular interactions between WPA oxygen atoms and different proton donor types (D=O, N, C), we have considered data for WPA based compounds from the Cambridge Structural Database (CSD), the Crystallographic Open Database (COD) and the Inorganic Crystal Structure Database (ICSD). Binding properties of Keggin's anion in biological systems are illustrated using Protein Data Bank (PDB). This work constitutes the first determination of theoretical Bader charges on polyoxotungstate compound via the Atom In Molecule theory. An analysis of electrostatic potential maps at the molecular surface and charge of WPA, resulting from DFT calculations, suggests that the preferred protonation site corresponds to WPA bridging oxygen. These results enlightened WPA chemical reactivity and its potential biological applications such as the inhibition of the ATPase activity.

Experimental evidence of charge transfer in a functionalized hexavanadate: a high resolution X-ray diffraction study.

A high resolution X-ray diffraction study has been carried out on [(C4H9)4N]2 [V6O13{(OCH2)3CCH2OCCH2CH3}2] (V6-C3) at 100 K. The V6 core possesses a negative charge, leading to a strong polarization of the anion. A nucleophilic region localized near the organic moiety and an electrophilic region in the vicinity of the V6 core provide an overall description of charge-transfer behavior.

Rising fluoroquinolone resistance in Campylobacter isolated from feedlot cattle in the United States.

Antibiotic resistance, particularly to fluoroquinolones and macrolides, in the major foodborne pathogen Campylobacter is considered a serious threat to public health. Although ruminant animals serve as a significant reservoir for Campylobacter, limited information is available on antibiotic-resistant Campylobacter of bovine origin. Here, we analyzed the antimicrobial susceptibilities of 320 C. jejuni and 115 C. coli isolates obtained from feedlot cattle farms in multiple states in the U.S. The results indicate that fluoroquinolone resistance reached to 35.4% in C. jejuni and 74.4% in C. coli, which are significantly higher than those previously reported in the U.S. While all fluoroquinolone resistant (FQR) C. coli isolates examined in this study harbored the single Thr-86-Ile mutation in GyrA, FQR C. jejuni isolates had other mutations in GyrA in addition to the Thr-86-Ile change. Notably, most of the analyzed FQR C. coli isolates had similar PFGE (pulsed field gel electrophoresis) patterns and the same MLST (multilocus sequence typing) sequence type (ST-1068) regardless of their geographic sources and time of isolation, while the analyzed C. jejuni isolates were genetically diverse, suggesting that clonal expansion is involved in dissemination of FQR C. coli but not C. jejuni. These findings reveal the rising prevalence of FQR Campylobacter in the U.S. and provide novel information on the epidemiology of antibiotic-resistant Campylobacter in the ruminant reservoir.

A combined crystallographic analysis and ab initio calculations to interpret the reactivity of functionalized hexavanadates and their inhibitor potency toward Na(+)/K(+)-ATPase.

In vitro influence of five synthesized functionalized hexavanadates (V6) on commercial porcine cerebral cortex Na(+)/K(+)-ATPase activity has been studied. Dose dependent Na(+)/K(+)-ATPase inhibition was obtained for all investigated compounds. Calculated half maximal inhibitory concentration IC50 values, in mol/L, for Na(+)/K(+)-ATPase were 7.6×10(-5), 1.8×10(-5), 2.9×10(-5), 5.5×10(-5) for functionalized hexavanadates (V6) with tetrabutylammonium (TBA) [V6-CH3][TBA]2, [V6-NO2][TBA]2, [V6-OH][TBA]2 and [V6-C3][TBA]2 respectively. [V6-OH][Na]2 inhibited Na(+)/K(+)-ATPase activity up to 30% at maximal investigated concentration 1×10(-3)mol/L. This reactivity has been interpreted using a study of the non-covalent interactions of functionalized hexavanadate hybrids through Cambridge Structural Database (CSD) analysis. Bibliographic searching has led to 18 different structures and 99 contacts. We have observed that C-H⋯O contacts consolidate the structures. We have also performed density functional theory (DFT) calculations and have determined electrostatic potential values at the molecular surface on a series of functionalized V6. These results enlightened their chemical reactivity and their potential biological applications such as the inhibition of the ATPase.

Campylobacter jejuni as a cause of canine abortions in the United States.

Although Campylobacter jejuni is a common cause of ruminant abortion with great economic impact, the organism has rarely been implicated in canine pregnancy loss, with only 2 documented cases to date. In the current report, 2 cases of perinatal death in adult female Bulldogs associated with C. jejuni infection of fetoplacental organs are described. Fetuses and placentas were received at the Iowa State University Veterinary Diagnostic Laboratory (Ames, Iowa) from 3 puppies that died soon after the birth (case 1) and from an aborted fetus (case 2). Microscopic examination of tissues was generally unremarkable; however, multifocal hemorrhage and infiltrates of macrophages and neutrophils were observed in placental sections from the first case (case 1), and low to moderate numbers of degenerate neutrophils were apparent within multifocal alveoli in the fetal lung in the second case (case 2). Ancillary diagnostics for common infectious causes of reproductive failure in dogs were negative. However, C. jejuni was isolated from the submitted placentas in high numbers in both cases as well as from the fetal lungs and livers. Genotyping of the abortion isolates indicated that the isolates were distinct from each other as well as from selected canine enteric C. jejuni isolates included herein for comparison. Both abortion strains were sensitive to all 9 antimicrobials tested, except the isolate from case 2, which displayed resistance to tetracycline. These findings provide convincing evidence for the inclusion of C. jejuni culture in routine diagnostic testing for causes of canine pregnancy loss.

Epidemiological, clinical and pathological characteristics of colorectal cancer in patients treated at the Clinical Center of Tuzla University.

AIM: To investigate hospital morbidity and incidence of colorectal cancer (CRC) in the Tuzla Canton between 2000 and 2004, as well as mortality incidence and degree of disease progression. METHODS: A total of 383 patients were enrolled in this study, all of them with CRC. Pathohistological analyses were performed in all patients after colonoscopy. Afterwards, the patients underwent surgery and obtained material was also pathohistologically analyzed in order to perform the Astler-Coller classification and the classification of the location of CRC. RESULTS: In the period 2000-2004 in the Tuzla Canton there were 383 newly diagnosed patients with CRC. The average age of the patients was 62 ± 12 years, and the incidence was equally distributed per genders. Rectal tumour was noted in 145 (37.9%) patients, and in 238 (62.1%) tumor was found elsewhere in the colon. Average incidence of the CRC was 15.73/100,000, with a dramatic increase in incidence in 2003 of 27.40/100,000. The average mortality incidence during the study was 6.89/100,000, and the largest number of the patients (339, 88.6%) was in an advanced stage of the disease. CONCLUSIONS: There has been a significant increase in the number of newly detected cases of CRC in the Tuzla Canton during 2000- 2004, which implies the need for initiating a National Early CRC Detection Programme.

Inhibition of rat synaptic membrane Na⁺/K⁺-ATPase and ecto-nucleoside triphosphate diphosphohydrolases by 12-tungstosilicic and 12-tungstophosphoric acid.

The in vitro influence of Keggin structure polyoxotungstates, 12-tungstosilicic acid, H(4)SiW(12)O(40) (WSiA) and 12-tungstophosphoric acid, H(3)PW(12)O(40) (WPA), and monomer Na(2)WO(4) × 2H(2)O on rat synaptic plasma membrane (SPM) Na(+)/K(+)-ATPase and E-NTPDase activity was studied, whereas the commercial porcine cerebral cortex Na(+)/K(+)-ATPase served as a reference. Dose-dependent Na(+)/K(+)-ATPase inhibition was obtained for all investigated compounds. Calculated IC(50) (10 min) values, in mol/l, for SPM/commercial Na(+)/K(+)-ATPase, were: 3.4 × 10(-6)/4.3 × 10(-6), 2.9 × 10(-6)/3.1 × 10(-6) and 1.3 × 10(-3)/1.5 × 10(-3) for WSiA, WPA and Na(2)WO(4) × 2H(2)O, respectively. In the case of E-NTPDase, increasing concentrations of WSiA and WPA induced its activity reduction, while Na(2)WO(4) × 2H(2)O did not noticeably affect the enzyme activity at all investigated concentrations (up to 1 × 10(-3)mol/l). IC(50) (10 min) values, obtained from the inhibition curves, were (in mol/l): 4.1 × 10(-6) for WSiA and 1.6 × 10(-6) for WPA. Monolacunary Keggin anion was found as the main active molecular species present under physiological conditions (in the enzyme assays, pH 7.4), for the both polyoxotungstates solutions (1 mmol/l), using Fourier transform infrared (FT-IR) and micro-Raman spectroscopy. Additionally, commercial porcine cerebral cortex Na(+)/K(+)-ATPase was exposed to the mixture of Na(2)WO(4) × 2H(2)O and WSiA at different concentrations. Additive inhibition effect was achieved for lower concentrations of Na(2)WO(4) × 2H(2)O/WSiA (≤ 1 × 10(-3)/4 × 10(-6) mol/l), while antagonistic effect was obtained for all higher concentrations of the inhibitors.

Cytosine-cytosinium dimer behavior in a cocrystal with a decavanadate anion as a function of the temperature.

We have performed X-ray diffraction measurements on single crystals of Na(3)[V(10)O(28)](C(4)N(3)OH(5))(3)(C(4)N(3)OH(6))(3)·10H(2)O as a function of the temperature. When the sample is cooled, from room temperature to 100 K, we have observed additional peaks well indexed in P1, while the phase at room temperature crystallizes in P1. The molecular structure at 210 K indicates that the center of inversion is located between two cytosinium molecules, formally described with a charge of +0.5. When this crystal is heated to room temperature and the structure in P1 reindexed, some peaks remained unindexed. A protonation-deprotonation process gives rise to additional diffraction peaks at temperatures lower than 210 K. The triply bridged hydrogen bonded cytosine-cytosinum dimer is discussed according to the results of the charge density analysis and topological analysis at 210 K. The structure at 100 K has been completely solved based on a comparative study with other compounds containing cytosine-cytosinium dimer. This description could be considered as a reference for such dimer. It could help for discrimination between cytosine and cytosinium molecules, for any new structure containing a cytosine-cytosinium pair, and for which the quality does not allow a precise determination of the hydrogen localization.

Mortality at the Clinic of Internal Medicine of University Clinical Center in Tuzla during 2008.

INTRODUCTION: Accurate information about the cause of death is given by expert teams based on pathological or forensic expertise. Reliable information can be obtained from doctors from clinical-hospital institutions if the deceased person was treated in such an institution and with previously diagnosed disease (hospital mortality). Analysis of hospital mortality provides a lot of data that can be used in planning the hospital beds capacities, the amount of drug procurement, purchasing equipment, organization and creation of highly specialized medical teams (medical team for resuscitation), the number of reanimation techniques, the number of pathologists who are required for autopsy procedures, etc. GOAL was to determine the total number of deaths, the most common causes of death and the 10 leading diagnoses of deceased patients at the Clinic for Internal Medicine of Clinical Center in Tuzla during 2008. MATERIAL AND METHODS: We used the material from the archive (medical records and reports on deceased patients, delivered by physicians working at the Clinic for Internal Medicine of Clinical Center in Tuzla). RESULTS: During 2008 at the Clinic for Internal Medicine 368 patients died. According to the analyzed data leading cause of death and leading diagnosis as cause of death at the Clinic for Internal Medicine in 2008 were as follows: cardiogenic shock in 73 (19.84%), cerebrovascular stroke in 46 (12.50%), coma due to stroke in 32 (8.70%), coma not classified as cerebral in 25 (6.79%) (metabolic 13 (3.53%) and hepatic 12 (3.26%), cardiomyopathy in 22 (5.98%), malignant neoplasm of the abdomen in 17 (4.62%), respiratory insufficiency in 17 (4.62%), acute myocardial infarction and myocardial infarction with rupture in 17 (4.62%), pulmonary edema in 16 (4.35%), and cardiorespiratory arrest in 13 (3.53%) deaths. CONCLUSION: During 2008 at the Clinic for Internal Medicine of Clinical Center in Tuzla died a total of 368 patients. The most common cause of death of patients at the Clinic for Internal Medicine of Clinical Center in Tuzla are cardiovascular disease (n = 175; 47.55% of deaths), in second place was cerebrovascular disease (n = 76; 20.65% of deaths) for a total of 251 (68.20%) of deaths from cardiovascular and cerebrovascular disease.

Influence of decavanadate on rat synaptic plasma membrane ATPases activity.

The in vitro influence of decameric vanadate species on Na+/K+-ATPase, plasma membrane Ca2+-ATPase (PMCA)-calcium pump and ecto-ATPase activity, using rat synaptic plasma membrane (SPM) as model system was investigated, whereas the commercial porcine cerebral cortex Na+/K+-ATPase served as a reference. The thermal behaviour of the synthesized decavanadate (V10) has been studied by differential scanning calorimetry and thermogravimetric analysis, while the type of polyvanadate anion was identified using the IR spectroscopy. The concentration-dependent responses to V10 of all enzymes were obtained. The half-maximum inhibitory concentration (IC50) of the enzyme activity was achieved at (4.74 +/- 1.15) x 10(-7) mol/l for SPM Na+/K+-ATPase, (1.30 +/- 0.10) x 10(-6) mol/l for commercial Na+/K+-ATPase and (3.13 +/- 1.70) x 10(-8) mol/l for Ca2+-ATPase, while ecto-ATPase is significantly less sensitive toward V10 (IC50 = (1.05 +/- 0.10) x 10(-4) mol/l) than investigated P-type ATPases. Kinetic analysis showed that V10 inhibited Na+/K+-ATPase by reducing the maximum enzymatic velocity and apparent affinity for ATP (increasing K(m) value), implying a mixed mode of interaction between V10 and P-type ATPases.

Electronic properties of a cytosine decavanadate: toward a better understanding of chemical and biological properties of decavanadates.

We have synthesized and crystallized a cytosine-decavanadate compound, Na(3) [V(10)O(28)] (C(4)N(3)OH(5))(3)(C(4)N(3)OH(6))(3).10H(2)O, and its crystal structure has been determined from a single-crystal X-ray diffraction. A high resolution X-ray diffraction experiment at 210 K (in P1 space group phase) was carried out. The data were refined using a pseudo-atom multipole model to get the electron density and the electrostatic properties of the decavanadate-cytosine complex. Static deformation density maps and Atoms in Molecules (AIM) topological analysis were used for this purpose. To get insight into the reactivity of the decavanadate anion, we have determined the atomic net charges and the molecular electrostatic potential. Special attention was paid to the hydrogen bonding occurring in the solid state between the decavanadate anion and its environment. The comparison of the experimental electronic characteristics of the decavanadate anions to those found in literature reveals that this anion is a rigid entity conserving its intrinsic properties. This is of particular importance for the future investigations of the biological activities of the decavanadate anion.

Reference frame congruency in search-and-rescue tasks.

OBJECTIVE: Our aim was to investigate how the congruency between visual displays and auditory cues affects performance on various spatial tasks. BACKGROUND: Previous studies have demonstrated that spatial auditory cues, when combined with visual displays, can enhance performance and decrease workload. However, this facilitation was achieved only when auditory cues shared a common reference frame (RF) with the visual display. In complex and dynamic environments, such as airborne search and rescue (SAR), it is often difficult to ensure such congruency. METHOD: In a simulated SAR operation, participants performed three spatial tasks: target search, target localization, and target recall. The interface consisted of the camera view of the terrain from the aircraft-mounted sensor, a map of the area flown over, a joystick that controlled the sensor, and a mouse. Auditory cues were used to indicate target location. While flying in the scenario, participants searched for targets, identified their locations in one of two coordinate systems, and memorized their location relative to the terrain layout. RESULTS: Congruent cues produced the fastest and most accurate performance. Performance advantages were observed even with incongruent cues relative to neutral cues, and egocentric cues were more effective than exocentric cues. CONCLUSION: Although the congruent cues are most effective, in cases in which the same cue is used across spatial tasks, egocentric cues are a better choice than exocentric cues. APPLICATION: Egocentric auditory cues should be used in display design for tasks that involve RF transformations, such as SAR, air traffic control, and unmanned aerial vehicle operations.

Smooth rotation of 2-D and 3-D representations of terrain: an investigation into the utility of visual momentum.

OBJECTIVE: The potential advantage of visual momentum in the form of smooth rotation between two-dimensional (2-D) and three-dimensional (3-D) displays of geographic terrain was examined. BACKGROUND: The relative effectiveness of 2-D and 3-D displays is task dependent, leading to the need for multiple frames of reference as users switch tasks. The use of smooth rotation to provide visual momentum has received little scrutiny in the task-switching context. A cognitive model of the processes involved in switching viewpoints on a set of spatial elements is proposed. METHODS: In three experiments, participants judged the properties of two points placed on terrain depicted as 2-D or 3-D displays. Participants indicated whether Point A was higher than Point B, or whether Point B could be seen from Point A. Participants performed the two tasks in pairs of trials, switching tasks and displays within the pair. In the continuous transition condition the display dynamically rotated in depth from one display format to the other. In the discrete condition there was an instantaneous viewpoint shift that varied across experiments (Experiment 1: immediate; Experiment 2: delay; Experiment 3: preview). RESULTS: Performance after continuous transition was superior to that after discrete transition. CONCLUSION: The visual momentum provided by smooth rotation helped users switch tasks. APPLICATION: The use of dynamic transition is recommended when observers examine multiple views of terrain over time. The model may serve as a useful heuristic for designers. The results are pertinent to command and control, geological engineering, urban planning, and imagery analysis domains.

Group differences in physician responses to handheld presentation of clinical evidence: a verbal protocol analysis.

BACKGROUND: To identify individual differences in physicians' needs for the presentation of evidence resources and preferences for mobile devices. METHODS: Within-groups analysis of responses to semi-structured interviews. Interviews consisted of using prototypes in response to task-based scenarios. The prototypes were implemented on two different form factors: a tablet style PC and a pocketPC. Participants were from three user groups: general internists, family physicians and medicine residents, and from two different settings: urban and semi-urban. Verbal protocol analysis, which consists of coding utterances, was conducted on the transcripts of the testing sessions. Statistical relationships were investigated between staff physicians' and residents' background variables, self-reported experiences with the interfaces, and verbal code frequencies. RESULTS: 47 physicians were recruited from general internal medicine, family practice clinics and a residency training program. The mean age of participants was 42.6 years. Physician specialty had a greater effect on device and information-presentation preferences than gender, age, setting or previous technical experience. Family physicians preferred the screen size of the tablet computer and were less concerned about its portability. Residents liked the screen size of the tablet, but preferred the portability of the pocketPC. Internists liked the portability of the pocketPC, but saw less advantage to the large screen of the tablet computer (F[2,44] = 4.94, p = .012). CONCLUSION: Different types of physicians have different needs and preferences for evidence-based resources and handheld devices. This study shows how user testing can be incorporated into the process of design to inform group-based customization.