1,054 research outputs found

    Serum (1 → 3)-β-d-glucan measurement as an early indicator of Pneumocystis jirovecii pneumonia and evaluation of its prognostic value

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    AbstractPneumocystis jirovecii (carinii) pneumonia (PJP) is a major cause of disease in immunocompromised individuals. However, until recently no reliable and specific serological parameters for the diagnosis of PJP have been available. (1 → 3)-β-d-Glucan (BG) is a cell wall component of P. jirovecii and of various other fungi. Data from the past few years have pointed to serum measurement of BG as a promising new tool for the diagnosis of PJP. We therefore conducted a retrospective study on 50 patients with PJP and 50 immunocompromised control patients to evaluate the diagnostic performance of serum BG measurement. Our results show an excellent diagnostic performance with a sensitivity of 98.0% and a specificity of 94%. While the positive predictive value was only 64.7%, the negative predictive value was 99.8% and therefore a negative BG result almost rules out PJP. BG levels were already strongly elevated in an average of 5 days and up to 21 days before microbiological diagnosis demonstrating that the diagnosis could have been confirmed earlier. BG levels at diagnosis and maximum BG levels during follow-up did not correlate with the outcome of patients or with the P. jirovecii burden in the lung as detected by Real-Time PCR. Therefore, absolute BG levels seem to be of no prognostic value. Altogether, BG is a reliable parameter for the diagnosis of PJP and could be used as a preliminary test for patients at risk before a bronchoalveolar lavage is performed

    ENERGETIC COSTS AND STRATEGIES OF POST‐JUVENAL MOLT IN AN EQUATORIAL BIRD, THE RUFOUS‐COLLARED SPARROW (ZONOTRICHIA CAPENSIS)

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    Abstract  ∙ Many tropical birds have slow‐paced life history strategies, exhibiting lower metabolic rates, reduced annual investment in reproduction, and longer lifespans relative to birds at higher latitudes. Life history strategies have been relatively well documented in adult individuals in the tropics, but we know comparatively little about the immature life history stage. Here we examine strategies of feather replacement (molt) and fattening in immature Rufous‐collared Sparrows (Zonotrichia capensis) in a high elevation equatorial population, following a parallel, previous study on an arctic congener, the White‐crowned Sparrow (Zonotrichia leucophrys gambelii). In captivity, Rufous‐ collared Sparrows incurred energetic costs of experimentally induced feather growth, similar to those previously described for Zonotrichia at higher latitudes. In contrast, free‐ranging immature Rufous‐collared Sparrows in natural molt had fat stores that declined over time, opposite to patterns evident in arctic Zonotrichia that fatten before migration. Equatorial birds in good condition molted more heavily (controlling for fat stores), suggesting that body condition limits the intensity of molt. Heavily molting equatorial sparrows also had lower amounts of fat (controlling for body condition), suggesting a trade‐off between allocation of resources to fat stores versus feather growth. Molt progressed slowly in Rufous‐collared Sparrows relative to previously described patterns in their arctic congener, which is concordant with a slower pace‐of‐life syndrome in tropical, as compared with high latitude, birds. Resumen ∙ Costos energéticos y estrategias de muda post‐juvenil en un ave ecuatorial, el Chingolo (Zonotrichia capensis) Muchas especies de aves tropicales presentan historias de vida lenta, exhibiendo bajas tasas metabólicas, esfuerzo reproductivo anual reducido, y mayor longevidad que las especies que habitan en latitudes más altas. La variación en historia de vida en especies tropicales ha sido bien documentada para individuos adultos, pero sabemos comparativa‐ mente poco de los individuos inmaduros. Aquí estudiamos las estrategias de muda y deposición de grasa en individuos inmaduros de Chingolo (Zonotrichia capensis) en una población ecuatorial de altura y comparamos los resultados con un estudio similar realizado en una población ártica del congénere Chingolo Coroniblanco (Zonotrichia leucophrys gambelii). En cautiverio, individuos juveniles de Z. capensis incurrieron costos energéticos debidos a la muda inducida, similar lo encontrado en Z. leucophrys gambelii. En contraste, Z. capensis inmaduros mudando en libertad presentaron depósitos de grasa que disminuyeron a lo largo del tiempo, lo opuesto a Z. l. gambelii, que deposita más grasa antes de migrar. Z. capensis inmaduros en buen estado nutricional (controlando por diferencias en deposición de grasa) mudaron de manera más intensa, lo que sugiere que el estado nutricional limita la muda. Individuos inmaduros de Z. capensis mudando de manera intensa presentaron menor cantidad de grasa depositada (controlando por diferencias en estado nutricional), lo que sugiere un balance entre la deposición de grasa y la muda. La muda fue más lenta en la población ecuatorial de Z. capensis comparado con la de Z. l. gambelii, lo que concuerda con lo esperado debido a la historia de vida más lenta en aves tropicales

    Interference Effects Due to Commensurate Electron Trajectories and Topological Crossovers in (TMTSF)2ClO4

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    We report angle-dependent magnetoresistance measurements on (TMTSF)2ClO4 that provide strong support for a new macroscopic quantum phenomenon, the interference commensurate (IC) effect, in quasi-one dimensional metals. In addition to observing rich magnetoresistance oscillations, and fitting them with one-electron calculations, we observe a clear demarcation of field-dependent behavior at local resistance minima and maxima (versus field angle). Anticipated by a theoretical treatment of the IC effect in terms of Bragg reflections in the extended Brillouin zone, this behavior results from 1D-2D topological crossovers of electron wave functions as a function of field orientation.Comment: 14 page

    Spin-density-wave transition of (TMTSF)2_2PF6_6 at high magnetic fields

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    The transverse magnetoresistance of the Bechgaard salt (TMTSF)2_2PF6_6 has been measured for various pressures, with the field up to 24 T parallel to the lowest conductivity direction c^{\ast}. A quadratic behavior is observed in the magnetic field dependence of the spin-density-wave (SDW) transition temperature TSDWT_{\rm {SDW}}. With increasing pressure, TSDWT_{\rm {SDW}} decreases and the coefficient of the quadratic term increases. These results are consistent with the prediction of the mean-field theory based on the nesting of the quasi one-dimensional Fermi surface. Using a mean field theory, TSDWT_{\rm {SDW}} for the perfect nesting case is estimated as about 16 K. This means that even at ambient pressure where TSDWT_{\rm {SDW}} is 12 K, the SDW phase of (TMTSF)2_2PF6_6 is substantially suppressed by the two-dimensionality of the system.Comment: 11pages,6figures(EPS), accepted for publication in PR

    Response of Temperate, Subtropical and Tropical Soybean Genotypes to Type-B Overflow Tidal Swamp of Indonesia

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    Twenty-nine soybean genotypes originating from various countries were evaluated on the tidal swamp of Indonesia to obtain information of agronomic character diversity as the soybean response to the environment and to obtain adaptive genotypes that can be used to develop soybean genotypes for the land. This study was conducted in a complete randomized block design with 3 replications. Diverse genetic backgrounds, countries and climatic regions of the 29 soybean genotypes were responsible for the difference in agronomic responses among the genotypes. All temperate and sub-tropical genotypes were able to produce seeds in the tropical type-B overflow tidal swamp. Adaptability based on seed yield resulted in 1 highly adaptive, 17 adaptive, 5 moderately adaptive and 6 non-adaptive genotypes. Adaptive and highly adaptive genotypes produced 1.56 - 2.58 tons ha-1 of seeds. Karasumame (Naihou), a subtropical genotype, produced the highest seed yield which was 65% higher than Indonesia average soybean productivity and 225% higher than soybean productivity with non-saturated soil culture technology on the tidal swamp. This study concluded that temperate and subtropical genotypes could be used as germplasm sources for soybean development in the tropical type-B overflow tidal swamp in Indonesia

    Partial Transmutation of Singularities in Optical Instruments

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    Some interesting optical instruments such as the Eaton lens and the Invisible Sphere require singularities of the refractive index for their implementation. We show how to transmute those singularities into harmless topological defects in anisotropic media without the need for anomalous material properties

    Determination of the Fermi Velocity by Angle-dependent Periodic Orbit Resonance Measurements in the Organic Conductor alpha-(BEDT-TTF)2KHg(SCN)4

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    We report detailed angle-dependent studies of the microwave (f=50 to 90 GHz) interlayer magneto-electrodynamics of a single crystal sample of the organic charge-density-wave (CDW) conductor alpha-(BEDT-TTF)2KHg(SCN)4. Recently developed instrumentation enables both magnetic field (B) sweeps for a fixed sample orientation and, for the first time, angle sweeps at fixed f/B. We observe series' of resonant absorptions which we attribute to periodic orbit resonances (POR) - a phenomenon closely related to cyclotron resonance. The angle dependence of the POR indicate that they are associated with the low temperature quasi-one-dimensional (Q1D) Fermi surface (FS) of the title compound; indeed, all of the resonance peaks collapse beautifully onto a single set of f/B versus angle curves, generated using a semiclassical magneto-transport theory for a single Q1D FS. We show that Q1D POR measurements provide one of the most direct methods for determining the Fermi velocity, without any detailed assumptions concerning the bandstructure; our analysis yields an average value of v_F=6.5x10^4 m/s. Quantitative analysis of the POR harmonic content indicates that the Q1D FS is strongly corrugated. This is consistent with the assumption that the low-temperature FS derives from a reconstruction of the high temperature quasi-two-dimensional FS, caused by the CDW instability. Detailed analysis of the angle dependence of the POR yields parameters associated with the CDW superstructure which are consistent with published results. Finally, we address the issue as to whether or not the interlayer electrodynamics are coherent in the title compound.Comment: 28 pages, including 6 figures. Submitted to PR

    Successful implementation of inquiry-based physiology laboratories in undergraduate major and nonmajor courses. Adv Physiol Educ 32

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    Casotti G, Rieser-Danner L, Knabb MT. Successful implementation of inquiry-based physiology laboratories in undergraduate major and nonmajor courses. Adv Physiol Educ 32: 286-296, 2008; doi:10.1152/advan.00100.2007.-Recent evidence has demonstrated that inquiry-based physiology laboratories improve students' criticaland analytical-thinking skills. We implemented inquiry-based learning into three physiology courses: Comparative Vertebrate Physiology (majors), Human Physiology (majors), and Human Anatomy and Physiology (nonmajors). The aims of our curricular modifications were to improve the teaching of physiological concepts, teach students the scientific approach, and promote creative and critical thinking. We assessed our modifications using formative (laboratory exams, oral presentations, and laboratory reports) and summative evaluations (surveys, laboratory notebook, and an end of semester project). Students appreciated the freedom offered by the new curriculum and the opportunity to engage in the inquiry process. Results from both forms of evaluation showed a marked improvement due to the curricular revisions. Our analyses indicate an increased confidence in students' ability to formulate questions and hypotheses, design experiments, collect and analyze data, and make conclusions. Thus, we have successfully incorporated inquiry-based laboratories in both major and nonmajor courses. pedagogy; curriculum; evaluation INQUIRY-BASED LEARNING is an alternative pedagogical method of classroom teaching that is characterized by a focus on learning through discovery. It incorporates four approaches to teaching: 1) a focus on ideas and concepts generated by students rather than by instructors, 2) an activity component where students actively participate in performing tasks (experiments) to test their ideas, 3) an emphasis on learning the methods of verifying and testing hypotheses, and 4) an emphasis on the importance of both content and process as components of learning Some individual studies of the effectiveness of an inquirybased approach have been reported. For example, DiPasquale et al. (2) modified the curriculum in an exercise physiology course at San Diego State University. The course was previously taught in a traditional style. Their new approach was to cover core exercise physiology topics in the first third of the course using the traditional teacher-centered style of learning while emphasizing the scientific process. In the last 9 wk of the course, students worked in small groups of three to four and completed independent research projects. In contrast, Myers and Burgess (11) redesigned an organismal physiology course centering on student-designed experiments throughout the course of the semester. Both studies reported an increase in student achievement of learning outcomes using student-designed experiments compared with a teacher-centered approach. Moreover, a recent review (10) published in Advances of Physiology Education summarized the evidence supporting the conclusion that forms of active learning, such as an inquirybased approach, are more effective in enhancing student learning than traditional modes of teaching. Problems With the Existing Curriculum The physiology curriculum using a teacher-centered approach resulted in several problems related to student learning. One of the problems was that students in our nonmajor course failed to connect physiological concepts taught in lecture with the laboratory activities. In addition, the laboratories did not emphasize the scientific approach to problem solving, and students were restricted in the types of experiments they were able to perform (13). Our old curriculum provided students with detailed step-bystep instructions for completing their experiments. As a result, students commented to the laboratory instructors that they lost sight of the educational purpose of the experiments. Furthermore, regimented instructions did not allow our students any flexibility to deviate from the experimental protocol, thereby impeding student creativity Students had no opportunity to develop their own understanding of physiology using the scientific approach. Even though our majors were required to write laboratory reports in prerequisite courses such as Cell Physiology and Organic Chemistry, they did not communicate their ideas effectively in a scientific report. For example, students did not refer to the neural control of respiration when discussing irregular respiratory patterns when solving a math problem. This resulted in low scores on laboratory reports. Clearly, this called for the need to offer students more opportunities using the scientific method, from researching background information to developing a testable hypothesis using appropriate written communication and reporting of scientific findings. Similar problems in understanding the scientific approach were also evident in our nonmajor course (see Precurricula Survey). Verbal comments from students in our physiology courses indicated a dissatisfaction with simply repeating experiments that had already been done by other researchers. Students could not see the purpose of performing some of the experiments, especially those involving animals, and often asked "Why ar
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