821 research outputs found
Adaptive Detection of Point-like Targets in Spectrally Symmetric Interference
We address adaptive radar detection of targets embedded in ground clutter dominated environments characterized by a symmetrically structured power spectral density. At the design stage, we leverage on the spectrum symmetry for the interference to come up with decision schemes capable of capitalizing the a-priori information on the covariance structure. To this end, we prove that the detection problem at hand can be formulated in terms of real variables and, then, we apply design procedures relying on the GLRT, the Rao test, and the Wald test. Specifically, the estimates of the unknown parameters under the target presence hypothesis are obtained through an iterative optimization algorithm whose convergence and quality guarantee is thoroughly proved. The performance analysis, both on simulated and on real radar data, confirms the superiority of the considered architectures over their conventional counterparts which do not take advantage of the clutter spectral symmetry
Identifying Important Observations Using Cross Validation and Computationally Frugal Sensitivity Analysis Methods
AbstractSensitivity analysis methods are used to identify measurements most likely to provide important information for model development and predictions. Methods range from computationally demanding Monte Carlo and cross-validation methods that require thousands to millions of model runs, to very computationally efficient linear methods able to account for interrelations between parameters that involve tens to hundreds of runs. Some argue that because linear methods neglect the effects of model nonlinearity, they are not worth considering. However, when faced with computationally demanding models needed to simulate, for example, climate change, the chance of obtaining insights with so few model runs is tempting. This work compares results for a nonlinear groundwater model using computationally demanding cross-validation and computationally efficient local sensitivity analysis methods
Bernardo A. Houssay : Vida y obra científica (1887-1971). Parte I
El 21 de septiembre de 1981 se cumplieron 10 años del fallecimiento de del Dr. Bernardo Houssay. Según el Sr. Presidente de la Academia Nacional de Ciencias Exactas, Físicas y Naturales, Dr. Luis A. Santaló, el mejor homenaje que se podría tributar con motivo de esa fecha, sería la publicación de una biografía escrita por colaboradores y discípulos conocedores directos de la vida y obra del ilustre Premio Nobel, la cual incluyera como Apéndice, alguno de sus artículos más significativos sobre Política Científica. La idea contó con la colaboración de la Academia Nacional de Medicina y el apoyo de la Subsecretaría de Cultura de la Nación y del Consejo Nacional de Investigaciones Científicas y Técnicas.Academia Nacional de Agronomía y Veterinaria (ANAV
Identifying Important Observations Using Cross Validation and Computationally Frugal Sensitivity Analysis Methods
Sensitivity analysis methods are used to identify measurements most likely to provide important information for model development and predictions. Methods range from computationally demanding Monte Carlo and cross-validation methods that require thousands to millions of model runs, to very computationally efficient linear methods able to account for interrelations between parameters that involve tens to hundreds of runs. Some argue that because linear methods neglect the effects of model nonlinearity, they are not worth considering. However, when faced with computationally demanding models needed to simulate, for example, climate change, the chance of obtaining insights with so few model runs is tempting. This work compares results for a nonlinear groundwater model using computationally demanding cross-validation and computationally efficient local sensitivity analysis methods
Bernardo A. Houssay : Vida y obra científica (1887-1971). Parte I
El 21 de septiembre de 1981 se cumplieron 10 años del fallecimiento de del Dr. Bernardo Houssay. Según el Sr. Presidente de la Academia Nacional de Ciencias Exactas, Físicas y Naturales, Dr. Luis A. Santaló, el mejor homenaje que se podría tributar con motivo de esa fecha, sería la publicación de una biografía escrita por colaboradores y discípulos conocedores directos de la vida y obra del ilustre Premio Nobel, la cual incluyera como Apéndice, alguno de sus artículos más significativos sobre Política Científica. La idea contó con la colaboración de la Academia Nacional de Medicina y el apoyo de la Subsecretaría de Cultura de la Nación y del Consejo Nacional de Investigaciones Científicas y Técnicas.Academia Nacional de Agronomía y Veterinaria (ANAV
Hand grip support for rehabilitation and assistance: from patent to TRL5
In the last decades, the continuous increase in the number of the vast cohort of chronic patients that constantly need medical assistance and supervision, and the widespread lack of therapist has brought to an increased interest in the role of medical technologies in rehabilitative programs and assistive scenarios. Current clinical evidence in rehabilitation demonstrates that there is an important and increasing demand for innovative therapeutic solutions to recover the hand functions to prevent patients to need assistance in performing daily life activities. This works describes the pathway from patent to TRLS of a device to support hand grip actions and interaction with daily life objects. E-KIRO is based on the use of electromagnets, which are able to attach/detach interactive objects equipped with a ferromagnetic plate. Five end-users used the device and scored it with excellent usability based on the System Usability Scale
Prognostic significance of organ dysfunction in cats with polytrauma
Polytrauma is a common emergency condition in small animals and is frequently associated with higher morbidity and mortality rates compared to minor trauma. Multiple Organ Dysfunction Syndrome (MODS) is a major complication of extensive traumatic injury, carrying a high risk of death despite intensive care treatment. Little is known about the prevalence and the prognostic impact of MODS in feline polytrauma. The current study aimed to prospectively evaluate the occurrence and the prognostic significance of organ dysfunction at admission in a population of polytraumatized cats. Cats with polytrauma requiring intensive care unit hospitalization were included and categorized according to outcome (survivors/non-survivors). Clinical and clinicopathological data, including scores of disease severity [Animal Trauma Triage Score (ATTS), APPLEfast, and APPLEfull], selected organ dysfunction and presence of MODS were evaluated upon admission, and analyzed with respect to mortality. Non-parametric statistics was performed and P < 0.05 was considered significant. Thirty-eight cats met the inclusion criteria: 8/38 (21%) had penetrating trauma, while 30/38 (79%) had blunt trauma. The overall in-hospital mortality was 37% (14/38). Cats with evidence of MODS upon admission had significantly higher frequency of death compared to cats without MODS (9/14 vs. 2/24 P = 0.0004). Hemostatic dysfunction, respiratory dysfunction, and MODS upon admission were significantly associated with mortality in the univariate logistic regression analysis (P = 0.005, P = 0.001, P = 0.001, respectively). The values of APPLEfast, APPLEfull, and ATTS were independently associated with a higher risk of death and positively correlated with the number of dysfunctional organs (P = 0.025, P = 0.004, P = 0.003, r = 0.57, P = 0.0002; r = 0.59, P = 0.0001; r = 0.55, P = 0.0003, respectively). Multiple Organ Dysfunction Syndrome is a common complication of feline polytrauma and its development is associated with increased disease severity and worse outcomes. The presence of hemostatic dysfunction and respiratory dysfunction upon admission is associated with a higher risk of death. The ATTS and the APPLE scores are useful prognostic tools for the assessment of cats with polytrauma
Bacterial survival following shock compression in the GigaPascal range
The possibility that life can exist within previously unconsidered habitats is causing us to expand our understanding of potential planetary biospheres. Significant populations of living organisms have been identified at depths extending up to several km below the Earth's surface; whereas laboratory experiments have shown that microbial species can survive following exposure to GigaPascal (GPa) pressures. Understanding the degree to which simple organisms such as microbes survive such extreme pressurization under static compression conditions is being actively investigated. The survival of bacteria under dynamic shock compression is also of interest. Such studies are being partly driven to test the hypothesis of potential transport of biological organisms between planetary systems. Shock compression is also of interest for the potential modification and sterilization of foodstuffs and agricultural products. Here we report the survival of Shewanella oneidensis bacteria exposed to dynamic (shock) compression. The samples examined included: (a) a "wild type" (WT) strain and (b) a "pressure adapted" (PA) population obtained by culturing survivors from static compression experiments to 750 MPa. Following exposure to peak shock pressures of 1.5 and 2.5 GPa the proportion of survivors was established as the number of colony forming units (CFU) present after recovery to ambient conditions. The data were compared with previous results in which the same bacterial samples were exposed to static pressurization to the same pressures, for 15 minutes each. The results indicate that shock compression leads to survival of a significantly greater proportion of both WT and PA organisms. The significantly shorter duration of the pressure pulse during the shock experiments (2-3 μs) likely contributes to the increased survival of the microbial species. One reason for this can involve the crossover from deformable to rigid solid-like mechanical relaxational behavior that occurs for bacterial cell walls on the order of seconds in the time dependent strain rate
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