94 research outputs found
Design, analysis, and test verification of advanced encapsulation systems
Design sensitivities are established for the development of photovoltaic module criteria and the definition of needed research tasks. The program consists of three phases. In Phase I, analytical models were developed to perform optical, thermal, electrical, and structural analyses on candidate encapsulation systems. From these analyses several candidate systems will be selected for qualification testing during Phase II. Additionally, during Phase II, test specimens of various types will be constructed and tested to determine the validity of the analysis methodology developed in Phase I. In Phse III, a finalized optimum design based on knowledge gained in Phase I and II will be developed. All verification testing was completed during this period. Preliminary results and observations are discussed. Descriptions of the thermal, thermal structural, and structural deflection test setups are included
Design, analysis and test verification of advanced encapsulation systems
Analytical models were developed to perform optical, thermal, electrical and structural analyses on candidate encapsulation systems. Qualification testing, specimens of various types, and a finalized optimum design are projected
Design, analysis and test verification of advanced encapsulation systems, phase 2 program results
Optical, electrical isolation, thermal structural, structural deflection, and thermal tests are reported. The utility of the optical, series capacitance, and structural deflection models was verified
Supersymmetry, quark confinement and the harmonic oscillator
We study some quantum systems described by noncanonical commutation relations
formally expressed as [q,p]=ihbar(I + chi H), where H is the associated
(harmonic oscillator-like) Hamiltonian of the system, and chi is a Hermitian
(constant) operator, i.e. [H,chi]=0 . In passing, we also consider a simple
(chi=0 canonical) model, in the framework of a relativistic Klein-Gordon-like
wave equation.Comment: To be published in Journal of Physics A: Mathematical and Theoretical
(2007
A Semantic Problem Solving Environment for Integrative Parasite Research: Identification of Intervention Targets for Trypanosoma cruzi
Effective research in parasite biology requires analyzing experimental lab data in the context of constantly expanding public data resources. Integrating lab data with public resources is particularly difficult for biologists who may not possess significant computational skills to acquire and process heterogeneous data stored at different locations. Therefore, we develop a semantic problem solving environment (SPSE) that allows parasitologists to query their lab data integrated with public resources using ontologies. An ontology specifies a common vocabulary and formal relationships among the terms that describe an organism, and experimental data and processes in this case. SPSE supports capturing and querying provenance information, which is metadata on the experimental processes and data recorded for reproducibility, and includes a visual query-processing tool to formulate complex queries without learning the query language syntax. We demonstrate the significance of SPSE in identifying gene knockout targets for T. cruzi. The overall goal of SPSE is to help researchers discover new or existing knowledge that is implicitly present in the data but not always easily detected. Results demonstrate improved usefulness of SPSE over existing lab systems and approaches, and support for complex query design that is otherwise difficult to achieve without the knowledge of query language syntax
Trypanosoma cruzi: a stage-specific calpain-like protein is induced after various kinds of stress
Radiating Effectiveness of Annular-Finned Space Radiators, Including Mutual Irradiation between Radiator Elements
the authors also provide an approximate quantitative number for the accuracy of the numerical results. Based on the authors' results of Figs. 8 and 9, the fully developed periodic flow is achieved at x/L = 4 and 30 for Re = 200 and 1600 respectively for L/H = 1. Would the authors first quantitatively define the periodic fully developed flow, and then provide the tabular values of x/L as functions of L/H and Re for L/H = 0.2,0.5,1,2 and 5, and the covered range of Re. A research task remains further refining the analytical model to correlate better the performance of interrupted wall surface with the experimental results. Subsequently, the more complex heat exchanger surfaces could be analyzed. In the meanwhile, this paper by Prof. Sparrow and his colleagues serves as a reminder that the flow and heat transfer phenomena in a compact heat exchanger are too complex to analyze. A better quantitative understanding of the flow phenomena is essential for better correlations and improved heat exchanger design. Additional Reference Authors' Closure We are appreciative of the perspectives conveyed by Dr. Shah's Discussion. With regard to the role of vortices and wakes, there are, assuredly, conditions where they will affect both the heat transfer and friction. On the other hand, there are conditions for which no significant effect will be felt. Perspectives on these conditions are conveyed in references [11] and [12]. In connection with the identification of the periodically developed regime in Figs. 8 and 9, there is considerable latitude depending on the selected criterion. Since all portions of a velocity or temperature profile do not develop with equal rapidity, there are various criteria that can be employed. It was for this reason that we did not quote development lengths in the paper. Additional References 11 Kottke, V., Blenke, H., and Schmidt, K. G., "The Influence of Nose Section and Turbulence Intensity on the Flow Around Thick Plates in Parallel Flow," Warme-und Stoffubertragung, Vol. 10,1977, pp. 159-174. 12 Loehrke, R. I., Roadman, R. E., and Read, G. W" ASME Paper The purpose of this discussion is to point out how one of Minning's results can be generalized. In his analysis of the inverted conical frustrum, Minning has chosen to express his results in terms of four variables-the cone half angle fi, the height of the frustrum h, the radial location of the differential element p, and the vertical distance from the differential element to the extended frustrums' vertex s. In my view, this last choice is not the natural one and indeed it obscures the generality of the result expressed by equation It appears that a better choice of variable would be the radius of the frustrum in the plane of the element or ring, which is given by r = -s tan fi. If s is thereby eliminated from equation With respect to this latter point, one may note, as was done for a cylinder by Sparrow, et al. [1] that the shape factor in question can be considered as the sum of two parts-one being a circular segment and, in this case, the other being a tilted triangular plate frustrum. 1 By C. P. Minning, published in the August, 1977 issue of the JOURNAL OP HEAT TRANSFER, Vol. 99, No. 3, The Aerospace Corporation, El Segundo, CA 90245. Since the former is known [2], the latter can be readily obtained and subsequently expressed in variables more suitable for that configuration. This, of course, introduces new possibilities too numerous to mention. Finally, since Minning does not mention any analytical checks of his result, it is pointed out that, when /3 = 0, it reduces to a form equivalent to that for the cylinder [1]. Additional References 1 Sparrow, E. M., Miller, G. B., and Jonsson, V. K., "Radiating Effectiveness of Annular-Finned Space Radiators, Including Mutual Irradiation between Radiator Elements," Journal Aerospace Sciences, Vol. 29, 1962, pp. 1291-1299 2 Sparrow, E. M., "A New and Simpler Formulation for Radiative Angle Factors," ASME JOURNAL OF HEAT TRANSFER, Vol. 85,1963, pp. 81-88. Author's Closure I appreciate Dr. Nelson's pointing out that the applicability of equation An alternate expression that avoids this confusion can be derived by substitution of the relation r = -s tanjtf, as suggested by Dr. Nelson, and the relation a = (7r/2) -fi into equation C^)] [(h cot a + r) -In this expression, a is the angle between the plane of dAi and the sloping side of the conical frustrum. Values of a are always positive and lie in the range 0 < « < TT. For 0 < « < 7r/2, the frustrum opens upward away from the plane of dA\. For 7r/2 < a < w, the frustrum opens downward toward the plane of dAi. The special case, a = it 12
Shoulder muscle endurance: the development of a standardized and reliable protocol
<p>Abstract</p> <p>Background</p> <p>Shoulder muscle fatigue has been proposed as a possible link to explain the association between repetitive arm use and the development of rotator cuff disorders. To our knowledge, no standardized clinical endurance protocol has been developed to evaluate the effects of muscle fatigue on shoulder function. Such a test could improve clinical examination of individuals with shoulder disorders. Therefore, the purpose of this study was to establish a reliable protocol for objective assessment of shoulder muscle endurance.</p> <p>Methods</p> <p>An endurance protocol was developed on a stationary dynamometer (Biodex System 3). The endurance protocol was performed in isotonic mode with the resistance set at 50% of each subject's peak torque as measured for shoulder external (ER) and internal rotation (IR). Each subject performed 60 continuous repetitions of IR/ER rotation. The endurance protocol was performed by 36 healthy individuals on two separate occasions at least two days apart. Maximal isometric shoulder strength tests were performed before and after the fatigue protocol to evaluate the effects of the endurance protocol and its reliability. Paired <it>t</it>-tests were used to evaluate the reduction in shoulder strength due to the protocol, while intraclass correlation coefficients (ICC) and minimal detectable change (MDC) were used to evaluate its reliability.</p> <p>Results</p> <p>Maximal isometric strength was significantly decreased after the endurance protocol (<it>P </it>< 0.001). The total work performed during the last third of the protocol was significantly less than the first third of the protocol (P < 0.05). The test-retest reliability of the post-fatigue strength measures was excellent (ICC >0.84).</p> <p>Conclusions</p> <p>Changes in muscular performance observed during and after the muscular endurance protocol suggests that the protocol did result in muscular fatigue. Furthermore, this study established that the resultant effects of fatigue of the proposed isotonic protocol were reproducible over time. The protocol was performed without difficulty by all volunteers and took less than 10 minutes to perform, suggesting that it might be feasible for clinical practice. This protocol could be used to induce local muscular fatigue in order to evaluate the effects of fatigue on shoulder kinematics or to evaluate changes in shoulder muscle endurance following rehabilitation.</p
Genome of the Avirulent Human-Infective Trypanosome—Trypanosoma rangeli
Background: Trypanosoma rangeli is a hemoflagellate protozoan parasite infecting humans and other wild and domestic mammals across Central and South America. It does not cause human disease, but it can be mistaken for the etiologic agent of Chagas disease, Trypanosoma cruzi. We have sequenced the T. rangeli genome to provide new tools for elucidating the distinct and intriguing biology of this species and the key pathways related to interaction with its arthropod and mammalian hosts. Methodology/Principal Findings: The T. rangeli haploid genome is ,24 Mb in length, and is the smallest and least repetitive trypanosomatid genome sequenced thus far. This parasite genome has shorter subtelomeric sequences compared to those of T. cruzi and T. brucei; displays intraspecific karyotype variability and lacks minichromosomes. Of the predicted 7,613 protein coding sequences, functional annotations could be determined for 2,415, while 5,043 are hypothetical proteins, some with evidence of protein expression. 7,101 genes (93%) are shared with other trypanosomatids that infect humans. An ortholog of the dcl2 gene involved in the T. brucei RNAi pathway was found in T. rangeli, but the RNAi machinery is non-functional since the other genes in this pathway are pseudogenized. T. rangeli is highly susceptible to oxidative stress, a phenotype that may be explained by a smaller number of anti-oxidant defense enzymes and heatshock proteins. Conclusions/Significance: Phylogenetic comparison of nuclear and mitochondrial genes indicates that T. rangeli and T. cruzi are equidistant from T. brucei. In addition to revealing new aspects of trypanosome co-evolution within the vertebrate and invertebrate hosts, comparative genomic analysis with pathogenic trypanosomatids provides valuable new information that can be further explored with the aim of developing better diagnostic tools and/or therapeutic targets
Trypanosoma cruzi Gene Expression in Response to Gamma Radiation
Trypanosoma cruzi is an organism highly resistant to ionizing radiation. Following a dose of 500 Gy of gamma radiation, the fragmented genomic DNA is gradually reconstructed and the pattern of chromosomal bands is restored in less than 48 hours. Cell growth arrests after irradiation but, while DNA is completely fragmented, RNA maintains its integrity. In this work we compared the transcriptional profiles of irradiated and non-irradiated epimastigotes at different time points after irradiation using microarray. In total, 273 genes were differentially expressed; from these, 160 were up-regulated and 113 down-regulated. We found that genes with predicted functions are the most prevalent in the down-regulated gene category. Translation and protein metabolic processes, as well as generation of precursor of metabolites and energy pathways were affected. In contrast, the up-regulated category was mainly composed of obsolete sequences (which included some genes of the kinetoplast DNA), genes coding for hypothetical proteins, and Retrotransposon Hot Spot genes. Finally, the tyrosyl-DNA phosphodiesterase 1, a gene involved in double-strand DNA break repair process, was up-regulated. Our study demonstrated the peculiar response to ionizing radiation, raising questions about how this organism changes its gene expression to manage such a harmful stress
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