The Angular Resolution Limit (ARL) is a fundamental statistical metric to quantify our ability to resolve two closely-spaced narrowband far-field complex sources. This statistical quantity, is ...defined as the minimal angular deviation between the two sources to be separated for a prefixed detection-based performance. In this work, we assume that the sources of interest are corrupted by a compound-Gaussian noise. In the standard literature, denoting with δ the true distance between the two sources, the derivation of the ARL is based on the statistical distribution of the Generalized Likelihood Ratio Test (GLRT) for a binary test where there is only one source under the null hypothesis (i.e., δ=0) and two sources under the alternative hypothesis δ ≠ 0. In literature, the true angular distance (TAD) is generally considered as an unknown deterministic parameter, then a maximum likelihood-based estimation of δ is exploited in the GLRT. In this paper, breaking away from existing contributions, we suppose that the TAD is a random variable, Gaussian distributed, meaning that δ∼N(δ0,σδ2). The TAD uncertainty can have many causes as for instance moving sources or/and platform, antenna calibration error, etc. In this work, a generic and flexible (but common) statistical model of the uncertain knowledge of the TAD is preferred instead of a too much specified error model. The degree of randomness (or uncertainty) is quantified by the ratio ξ=δ02/σδ2. The standard framework of the GLRT is no longer feasible for our problem formulation. To cope with the compound Gaussian noise modeling and the random model of the TAD, a powerful upper bound from information/geometry theory is exploited in this work. More precisely, a new expected Chernoff Upper Bound (CUB) on the minimal error probability is introduced. Based on the analysis of this upper bound, we show that the expected-CUB is highly dependent on the degree of uncertainty, ξ. As a by-product, the optimal s-value in the Chernoff divergence for which the expected-CUB is the tightest upper bound is analytically studied and the role of the mean value δ0 in the ARL context is analyzed.
Statistical analysis of bistatic and monostatic sea clutter Palama, Riccardo; Greco, Maria S.; Stinco, Pietro ...
IEEE transactions on aerospace and electronic systems,
2015-Oct., 2015-10-00, 20151001, Letnik:
51, Številka:
4
Journal Article
Recenzirano
Odprti dostop
In this work, we analyze the sea clutter data collected simultaneously by the bistatic and monostatic nodes of an S-band netted radar system under different out-of-plane geometries. The empirical ...distribution of sea clutter data are fitted to some known heavy-tailed distributions, and the sea spikes statistics are examined. Our analyses show that spikiness is higher for small bistatic angles and that bistatic data are sometimes less spiky than monostatic ones only for horizontal polarization.
Transperineal ultrasound (TPUS) is a practical tool for assessing perianal inflammatory lesions. We systematically review its accuracy for detecting and classifying perianal fistulae and abscesses.
...The National Library of Medicine and Embase were searched for articles on TPUS for the assessment of idiopathic and Crohn's perianal fistulae and abscesses. Two reviewers independently reviewed eligible studies and rated them for quality using the QUADAS tool. The primary outcome measure was the accuracy of TPUS as measured by its sensitivity and positive predictive value (PPV) in detecting and classifying perianal fistulae, internal openings and perianal abscesses.
We included 12 studies (565 patients). Overall, the methodological quality of the studies was suboptimal. 3 studies were retrospective and 4 showed significant risks of bias in the application of the reference standard. The sensitivity of TPUS in detecting perianal fistulae on a per-lesion basis was 98 % (95 % CI 96 - 100 %) and the PPV was 95 % (95 % CI 90 - 98 %). The detection of internal openings had a sensitivity of 91 % (95 % CI 84 - 97 %) with a PPV of 87 % (95 % CI 76 - 95 %). The classification of fistulae yielded a sensitivity of 92 % (95 % CI 85 - 97 %) and a PPV of 92 % (95 % CI 83 - 98 %). TPUS had a sensitivity of 86 % (95 % CI 67 - 99 %) and PPV of 90 % (95 % CI 76 - 99 %) in the detection of perianal abscesses.
The current literature on TPUS illustrates good overall accuracy in the assessment of perianal fistulae and abscesses. However, many studies had methodological flaws suggesting that further research is required.
Several variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have emerged during the current coronavirus disease 2019 (COVID-19) pandemic. Although antibody cross-reactivity with ...the spike glycoproteins (S) of diverse coronaviruses, including endemic common cold coronaviruses (HCoVs), has been documented, it remains unclear whether such antibody responses, typically targeting the conserved S2 subunit, contribute to protection when induced by infection or through vaccination. Using a mouse model, we found that prior HCoV-OC43 S-targeted immunity primes neutralizing antibody responses to otherwise subimmunogenic SARS-CoV-2 S exposure and promotes S2-targeting antibody responses. Moreover, vaccination with SARS-CoV-2 S2 elicited antibodies in mice that neutralized diverse animal and human alphacoronaviruses and betacoronaviruses in vitro and provided a degree of protection against SARS-CoV-2 challenge in vivo. Last, in mice with a history of SARS-CoV-2 Wuhan-based S vaccination, further S2 vaccination induced broader neutralizing antibody response than booster Wuhan S vaccination, suggesting that it may prevent repertoire focusing caused by repeated homologous vaccination. These data establish the protective value of an S2-targeting vaccine and support the notion that S2 vaccination may better prepare the immune system to respond to the changing nature of the S1 subunit in SARS-CoV-2 variants of concern, as well as to future coronavirus zoonoses.
We used a pharmacophore hybridization strategy to combine key structural elements of merbarone and etoposide and generated new type II topoisomerase (topoII) poisons. This first set of hybrid topoII ...poisons shows promising antiproliferative activity on human cancer cells, endorsing their further exploration for anticancer drug discovery.
The oncogenic KRAS mutation has a critical role in the initiation of human pancreatic ductal adenocarcinoma (PDAC) since it rewires glutamine metabolism to increase reduced nicotinamide adenine ...dinucleotide phosphate (NADPH) production, balancing cellular redox homeostasis with macromolecular synthesis
. Mitochondrial glutamine-derived aspartate must be transported into the cytosol to generate metabolic precursors for NADPH production
. The mitochondrial transporter responsible for this aspartate efflux has remained elusive. Here, we show that mitochondrial uncoupling protein 2 (UCP2) catalyses this transport and promotes tumour growth. UCP2-silenced KRAS
cell lines display decreased glutaminolysis, lower NADPH/NADP
and glutathione/glutathione disulfide ratios and higher reactive oxygen species levels compared to wild-type counterparts. UCP2 silencing reduces glutaminolysis also in KRAS
PDAC cells but does not affect their redox homeostasis or proliferation rates. In vitro and in vivo, UCP2 silencing strongly suppresses KRAS
PDAC cell growth. Collectively, these results demonstrate that UCP2 plays a vital role in PDAC, since its aspartate transport activity connects the mitochondrial and cytosolic reactions necessary for KRAS
rewired glutamine metabolism
, and thus it should be considered a key metabolic target for the treatment of this refractory tumour.
Laboratory Animals Technologist degree (Técnico Universitario en Gestión Integral de Bioterios) was created in 1989. It is offered jointly by the Faculty of Veterinary Sciences and the Faculty of ...Pharmacy and Biochemistry at the University of Buenos Aires. The complete programme is organized into 15 courses, including basic and applied sciences, along with specific courses (Técnicas de Bioterio I to V) with a solid practice content that students must achieve.
An additional challenge occurs when practices consist of animal handling and procedures, which can be stressful for students and animals. Since traditional evaluation methods may not be the best way to determine the acquisition of knowledge and practical performance, an evaluation rubric is proposed to assess the practices carried out by students.
The aspects and criteria to be examined were previously known of by students and teachers. The evaluation levels include: ‘Daily report and record-keeping’, ‘Food and water supply’, ‘Cleaning and disinfection of areas, Standardized Operational Procedures and routines fulfilment’, ‘Personnel and supplies circulation’, ‘Use of personal protection equipment and physical care’, ‘Fulfilment of tasks in established times’, ‘Animals procedures and organization of needed materials’, ‘Animal care’ and ‘Teamwork camaraderie and organization’.
The proposed tool was implemented with good results to achieve the academic objectives while augmenting the confidence for practical expertise, minimizing doubts and uncertainties related to traditional evaluation methods, and providing students with an environment that favours knowledge acquisition and practical skills, establishing standard criteria among the teaching staff, and reducing and refining the use of animals for educational purposes.
In this paper we deal with the problem of calculating the Cramer-Rao lower bounds (CRLBs) for bistatic radar channels. To this purpose we exploited the relation between the ambiguity function (AF) ...and the CRLB. The bistatic CRLBs are analyzed and compared with the monostatic counterparts as a function of the bistatic geometric parameters. In the bistatic case both geometry factors and transmitted waveforms play an important role in the shape of the AF, and therefore in the estimation accuracy of the target range and velocity. In particular, the CRLBs depend on the target direction of arrival (DOA), the bistatic baseline length (BBL), and the distance between the target and the receiver. The CRLBs are then used to select the "optimum" bistatic channel (or set of channels) for the tracking of a radar target moving along a trajectory in a multistatic scenario.
The current manuscript explores Twitter use and content in the precrisis stages of a major weather event in the northeast. A multi-level content analysis of tweets collected in the lead up to ...landfall suggests that emergency management agencies largely underutilized the medium, and that actionable information was easier to find when searching along localized hashtags. The findings are discussed in terms of the Crisis and Emergency Risk Communication (CERC) model of crisis management and implications for emergency management agencies.
•We examined a large number of tweets in the days leading up to a major snowstorm.•Twitter content dealt more with affective orientation than actionable information.•Actionable information was easier to find using localized hashtags.•Emergency management agencies were largely absent from the conversation.
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