On the segmentation of astronomical images via level-set methods

Astronomical images are of crucial importance for astronomers since they contain a lot of information about celestial bodies that can not be directly accessible. Most of the information available for the analysis of these objects starts with sky explorations via telescopes and satellites. Unfortunately, the quality of astronomical images is usually very low with respect to other real images and this is due to technical and physical features related to their acquisition process. This increases the percentage of noise and makes more difficult to use directly standard segmentation methods on the original image. In this work we will describe how to process astronomical images in two steps: in the first step we improve the image quality by a rescaling of light intensity whereas in the second step we apply level-set methods to identify the objects. Several experiments will show the effectiveness of this procedure and the results obtained via various discretization techniques for level-set equations.Comment: 24 pages, 59 figures, paper submitte

An Elastic Interaction-Based Loss Function for Medical Image Segmentation

Deep learning techniques have shown their success in medical image segmentation since they are easy to manipulate and robust to various types of datasets. The commonly used loss functions in the deep segmentation task are pixel-wise loss functions. This results in a bottleneck for these models to achieve high precision for complicated structures in biomedical images. For example, the predicted small blood vessels in retinal images are often disconnected or even missed under the supervision of the pixel-wise losses. This paper addresses this problem by introducing a long-range elastic interaction-based training strategy. In this strategy, convolutional neural network (CNN) learns the target region under the guidance of the elastic interaction energy between the boundary of the predicted region and that of the actual object. Under the supervision of the proposed loss, the boundary of the predicted region is attracted strongly by the object boundary and tends to stay connected. Experimental results show that our method is able to achieve considerable improvements compared to commonly used pixel-wise loss functions (cross entropy and dice Loss) and other recent loss functions on three retinal vessel segmentation datasets, DRIVE, STARE and CHASEDB1

Education: Expectation and the Unexpected

In this paper I consider the concept of expectation in Higher Education. To focus the discussion I begin by sketching out some examples of how this notion pervades a number of practices in the university, and how in particular, expectation drives the way that the university tutorial operates between tutors and students. In relating this to the tendency towards what has been identified as the marketization and consumerism of higher education, I draw on the distinction that Paul Standish identifies between and ‘economy of exchange’ and an ‘economy of excess’, and suggest how expectation and responsibility figure in these economies. In moving to think beyond narrow conceptions of expectation and responsibility, and beyond the literature on policy and management in higher education, I turn to the work of the Jewish philosophers, Martin Buber and Emmanuel Levinas to show how they have both given attention to richer ideas of relationship, responsibility and the other. I initially outline Buber’s central work on the distinction between I-It and I-Thou modes of relationship, and how the latter is characterised by a dialogic intersubjectivity. I contrast this with the work of Emmanuel Levinas and draw out the distinction between the mutuality at the heart of Buber’s work, and the relationship of asymmetry that mark’s Levinas’ conception of our responsibility to the other, which is ethics. Having drawn the distinction, I then show how there are lines of connection in their respective philosophical projects, specifically how speech or dialogue is central to the relationship with the other in both thinkers. I find in both Buber and Levinas that speech cannot be thought of solely as communication. This has significant implications for education: speech is not simply the communication of (curricular) content between tutor and student. Given this, teaching can be thought of as a space for encounter with the other through language. This has further implications for thinking about the place of the tutorial in a university education. At this point I return to the scene of the university tutorial and suggest that, rather than seeing it as a place only for the meeting of expectations (which would suggest a closed economy of exchange), it might be envisioned as a space for encounter with the unexpected. In considering the nature of the encounter in relation to an example from the film adaptation of Alan Bennett’s The History Boys, I argue that the tutorial opens up the possibility for a mutual encounter with otherness. This positions the tutorial as a space of educational otherness, - a Foucauldian heterotopia which rejects the expectation-bound economy of exchange, and which offers instead the possibility of an education marked instead by an economy of excess. <br/

Psychotherapy as a treatment modality for psychiatric disorders: Perceptions of general public of Karachi, Pakistan

<p>Abstract</p> <p>Background</p> <p>Psychiatric disorders affect about 450 million individuals worldwide. A number of treatment modalities such as psychotropic medications, psychotherapy and electroconvulsive therapy can be used to treat these disorders. Attitudes of general public play a pivotal role in effective utilization of mental health services. We explored the perceptions of general public of Karachi, Pakistan regarding psychotherapy.</p> <p>Methods</p> <p>A cross-sectional study was conducted in Karachi, Pakistan during July-August, 2008. A three-step sampling strategy and a structured questionnaire were employed to survey knowledge and perceptions of adult general public about psychotherapy. Descriptive statistics were used for baseline characteristics. Logistic regression models were used to investigate any significant associations between baseline characteristics of the participants and their perceptions.</p> <p>Results</p> <p>The study sample comprised of 985 individuals (536 males; 531 financially independent) with an average age of 36.7 years (SD 13.54 years) and 12.5 years (SD 3.09 years) of education were included. Majority (59.4%; n = 585) claimed to be aware of psychotherapy as a treatment option for psychiatric disorders but 47.5% of these (n = 278/585) failed to identify its correct definition. Concerns voiced by the participants about psychotherapy included stigma (48.7%) and breech in confidentiality (39.5%); 60.7% opined it cost effective and 86.5% favored its use as an adjuvant modality. A preference for psychotherapy as the treatment strategy for psychiatric disorders was demonstrated by 46.6% (n = 459/985). Younger, more educated, financially independent and female participants were more likely to prefer psychotherapy as were those who deemed it cost effective.</p> <p>Conclusion</p> <p>Positive attitudes regarding the acceptability, clinical utility and cost-effectiveness of psychotherapy were observed in a sample representative of general public of Karachi, Pakistan. These findings highlight its potential utility for devising pragmatic mental health strategies in the face of limited resources.</p

Medical communication and technology: a video-based process study of the use of decision aids in primary care

Background: much of the research on decision-making in health care has focused on consultation outcomes. Less is known about the process by which clinicians and patients come to a treatment decision. This study aimed to quantitatively describe the behaviour shown by doctors and patients during primary care consultations when three types of decision aids were used to promote treatment decision-making in a randomised controlled trial.Methods: a video-based study set in an efficacy trial which compared the use of paper-based guidelines (control) with two forms of computer-based decision aids (implicit and explicit versions of DARTS II). Treatment decision concerned warfarin anti-coagulation to reduce the risk of stroke in older patients with atrial fibrillation. Twenty nine consultations were video-recorded. A ten-minute 'slice' of the consultation was sampled for detailed content analysis using existing interaction analysis protocols for verbal behaviour and ethological techniques for non-verbal behaviour.Results: median consultation times (quartiles) differed significantly depending on the technology used. Paper-based guidelines took 21 (19–26) minutes to work through compared to 31 (16–41) minutes for the implicit tool; and 44 (39–55) minutes for the explicit tool. In the ten minutes immediately preceding the decision point, GPs dominated the conversation, accounting for 64% (58–66%) of all utterances and this trend was similar across all three arms of the trial. Information-giving was the most frequent activity for both GPs and patients, although GPs did this at twice the rate compared to patients and at higher rates in consultations involving computerised decision aids. GPs' language was highly technically focused and just 7% of their conversation was socio-emotional in content; this was half the socio-emotional content shown by patients (15%). However, frequent head nodding and a close mirroring in the direction of eye-gaze suggested that both parties were active participants in the conversationConclusion: irrespective of the arm of the trial, both patients' and GPs' behaviour showed that they were reciprocally engaged in these consultations. However, even in consultations aimed at promoting shared decision-making, GPs' were verbally dominant, and they worked primarily as information providers for patients. In addition, computer-based decision aids significantly prolonged the consultations, particularly the later phases. These data suggest that decision aids may not lead to more 'sharing' in treatment decision-making and that, in their current form, they may take too long to negotiate for use in routine primary car

Site-Directed Mutations and the Polymorphic Variant Ala160Thr in the Human Thromboxane Receptor Uncover a Structural Role for Transmembrane Helix 4

The human thromboxane A2 receptor (TP), belongs to the prostanoid subfamily of Class A GPCRs and mediates vasoconstriction and promotes thrombosis on binding to thromboxane (TXA2). In Class A GPCRs, transmembrane (TM) helix 4 appears to be a hot spot for non-synonymous single nucleotide polymorphic (nsSNP) variants. Interestingly, A160T is a novel nsSNP variant with unknown structure and function. Additionally, within this helix in TP, Ala1604.53 is highly conserved as is Gly1644.57. Here we target Ala1604.53 and Gly1644.57 in the TP for detailed structure-function analysis. Amino acid replacements with smaller residues, A160S and G164A mutants, were tolerated, while bulkier beta-branched replacements, A160T and A160V showed a significant decrease in receptor expression (Bmax). The nsSNP variant A160T displayed significant agonist-independent activity (constitutive activity). Guided by molecular modeling, a series of compensatory mutations were made on TM3, in order to accommodate the bulkier replacements on TM4. The A160V/F115A double mutant showed a moderate increase in expression level compared to either A160V or F115A single mutants. Thermal activity assays showed decrease in receptor stability in the order, wild type>A160S>A160V>A160T>G164A, with G164A being the least stable. Our study reveals that Ala1604.53 and Gly1644.57 in the TP play critical structural roles in packing of TM3 and TM4 helices. Naturally occurring mutations in conjunction with site-directed replacements can serve as powerful tools in assessing the importance of regional helix-helix interactions

Discovery of DNA Viruses in Wild-Caught Mosquitoes Using Small RNA High throughput Sequencing

BACKGROUND: Mosquito-borne infectious diseases pose a severe threat to public health in many areas of the world. Current methods for pathogen detection and surveillance are usually dependent on prior knowledge of the etiologic agents involved. Hence, efficient approaches are required for screening wild mosquito populations to detect known and unknown pathogens. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we explored the use of Next Generation Sequencing to identify viral agents in wild-caught mosquitoes. We extracted total RNA from different mosquito species from South China. Small 18-30 bp length RNA molecules were purified, reverse-transcribed into cDNA and sequenced using Illumina GAIIx instrumentation. Bioinformatic analyses to identify putative viral agents were conducted and the results confirmed by PCR. We identified a non-enveloped single-stranded DNA densovirus in the wild-caught Culex pipiens molestus mosquitoes. The majority of the viral transcripts (.>80% of the region) were covered by the small viral RNAs, with a few peaks of very high coverage obtained. The +/- strand sequence ratio of the small RNAs was approximately 7∶1, indicating that the molecules were mainly derived from the viral RNA transcripts. The small viral RNAs overlapped, enabling contig assembly of the viral genome sequence. We identified some small RNAs in the reverse repeat regions of the viral 5'- and 3' -untranslated regions where no transcripts were expected. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate for the first time that high throughput sequencing of small RNA is feasible for identifying viral agents in wild-caught mosquitoes. Our results show that it is possible to detect DNA viruses by sequencing the small RNAs obtained from insects, although the underlying mechanism of small viral RNA biogenesis is unclear. Our data and those of other researchers show that high throughput small RNA sequencing can be used for pathogen surveillance in wild mosquito vectors

Towards a Processual Microbial Ontology

types: ArticleStandard microbial evolutionary ontology is organized according to a nested hierarchy of entities at various levels of biological organization. It typically detects and defines these entities in relation to the most stable aspects of evolutionary processes, by identifying lineages evolving by a process of vertical inheritance from an ancestral entity. However, recent advances in microbiology indicate that such an ontology has important limitations. The various dynamics detected within microbiological systems reveal that a focus on the most stable entities (or features of entities) over time inevitably underestimates the extent and nature of microbial diversity. These dynamics are not the outcome of the process of vertical descent alone. Other processes, often involving causal interactions between entities from distinct levels of biological organisation, or operating at different time scales, are responsible not only for the destabilisation of pre-existing entities, but also for the emergence and stabilisation of novel entities in the microbial world. In this article we consider microbial entities as more or less stabilised functional wholes, and sketch a network-based ontology that can represent a diverse set of processes including, for example, as well as phylogenetic relations, interactions that stabilise or destabilise the interacting entities, spatial relations, ecological connections, and genetic exchanges. We use this pluralistic framework for evaluating (i) the existing ontological assumptions in evolution (e.g. whether currently recognized entities are adequate for understanding the causes of change and stabilisation in the microbial world), and (ii) for identifying hidden ontological kinds, essentially invisible from within a more limited perspective. We propose to recognize additional classes of entities that provide new insights into the structure of the microbial world, namely ‘‘processually equivalent’’ entities, ‘‘processually versatile’’ entities, and ‘‘stabilized’’ entities.Economic and Social Research Council, U

Magnetic Resonance Imaging in Huntington's Disease.

Magnetic resonance imaging (MRI) is a noninvasive technique used routinely to image the body in both clinical and research settings. Through the manipulation of radio waves and static field gradients, MRI uses the principle of nuclear magnetic resonance to produce images with high spatial resolution, appropriate for the investigation of brain structure and function