6,481 research outputs found
Measuring every particle's size from three-dimensional imaging experiments
Often experimentalists study colloidal suspensions that are nominally
monodisperse. In reality these samples have a polydispersity of 4-10%. At the
level of an individual particle, the consequences of this polydispersity are
unknown as it is difficult to measure an individual particle size from
microscopy. We propose a general method to estimate individual particle radii
within a moderately concentrated colloidal suspension observed with confocal
microscopy. We confirm the validity of our method by numerical simulations of
four major systems: random close packing, colloidal gels, nominally
monodisperse dense samples, and nominally binary dense samples. We then apply
our method to experimental data, and demonstrate the utility of this method
with results from four case studies. In the first, we demonstrate that we can
recover the full particle size distribution {\it in situ}. In the second, we
show that accounting for particle size leads to more accurate structural
information in a random close packed sample. In the third, we show that crystal
nucleation occurs in locally monodisperse regions. In the fourth, we show that
particle mobility in a dense sample is correlated to the local volume fraction.Comment: 7 pages, 5 figure
Reasoning from connectives and relations between entities
This article reports investigations of inferences that depend both on connectives between clauses, such as or else, and on relations between entities, such as in the same place as. Participants made more valid inferences from biconditionals—for instance, Ann is taller than Beth if and only if Beth is taller than Cath—than from exclusive disjunctions (Exp. 1). They made more valid transitive inferences from a biconditional when a categorical premise affirmed rather than denied one of its clauses, but they made more valid transitive inferences from an exclusive disjunction when a categorical premise denied rather than affirmed one of its clauses (Exp. 2). From exclusive disjunctions, such as Either Ann is not in the same place as Beth or else Beth is not in the same place as Cath, individuals tended to infer that all three individuals could be in different places, whereas in fact this was impossible (Exps. 3a and 3b). The theory of mental models predicts all of these results
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Dermoscopy for melanoma detection and triage in primary care: a systematic review.
OBJECTIVE: Most skin lesions first present in primary care, where distinguishing rare melanomas from benign lesions can be challenging. Dermoscopy improves diagnostic accuracy among specialists and is promoted for use by primary care physicians (PCPs). However, when used by untrained clinicians, accuracy may be no better than visual inspection. This study aimed to undertake a systematic review of literature reporting use of dermoscopy to triage suspicious skin lesions in primary care settings, and challenges for implementation. DESIGN: A systematic literature review and narrative synthesis. DATA SOURCES: We searched MEDLINE, Cochrane Central, EMBASE, Cumulative Index to Nursing and Allied Health Literature, and SCOPUS bibliographic databases from 1 January 1990 to 31 December 2017, without language restrictions. INCLUSION CRITERIA: Studies including assessment of dermoscopy accuracy, acceptability to patients and PCPs, training requirements, and cost-effectiveness of dermoscopy modes in primary care, including trials, diagnostic accuracy and acceptability studies. RESULTS: 23 studies met the review criteria, representing 49 769 lesions and 3708 PCPs, all from high-income countries. There was a paucity of studies set truly in primary care and the outcomes measured were diverse. The heterogeneity therefore made meta-analysis unfeasible; the data were synthesised through narrative review. Dermoscopy, with appropriate training, was associated with improved diagnostic accuracy for melanoma and benign lesions, and reduced unnecessary excisions and referrals. Teledermoscopy-based referral systems improved triage accuracy. Only three studies examined cost-effectiveness; hence, there was insufficient evidence to draw conclusions. Costs, training and time requirements were considered important implementation barriers. Patient satisfaction was seldom assessed. Computer-aided dermoscopy and other technological advances have not yet been tested in primary care. CONCLUSIONS: Dermoscopy could help PCPs triage suspicious lesions for biopsy, urgent referral or reassurance. However, it will be important to establish further evidence on minimum training requirements to reach competence, as well as the cost-effectiveness and patient acceptability of implementing dermoscopy in primary care. TRIAL REGISTRATION NUMBER: CRD42018091395.CRU
H_2 emission arises outside photodissociation regions in ultra-luminous infrared galaxies
Ultra-luminous infrared galaxies are among the most luminous objects in the
local universe and are thought to be powered by intense star formation. It has
been shown that in these objects the rotational spectral lines of molecular
hydrogen observed at mid-infrared wavelengths are not affected by dust
obscuration, leaving unresolved the source of excitation of this emission. Here
I report an analysis of archival Spitzer Space Telescope data on ultra-luminous
infrared galaxies and demonstrate that star formation regions are buried inside
optically thick clouds of gas and dust, so that dust obscuration affects
star-formation indicators but not molecular hydrogen. I thereby establish that
the emission of H_2 is not co-spatial with the buried starburst activity and
originates outside the obscured regions. This is rather surprising in light of
the standard view that H_2 emission is directly associated with star-formation
activity. Instead, I propose that H_2 emission in these objects traces shocks
in the surrounding material, which are in turn excited by interactions with
nearby galaxies, and that powerful large-scale shocks cooling by means of H_2
emission may be much more common than previously thought. In the early
universe, a boost in H_2 emission by this process may speed up the cooling of
matter as it collapsed to form the first stars and galaxies and would make
these first structures more readily observable.Comment: Main text and supplemental information, 21 pages including 6 figures,
2 table
Plasma from septic shock patients induces loss of muscle protein
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97225.pdf (publisher's version ) (Open Access
Pre-eclampsia Diagnosis and Treatment Options: A Review of Published Economic Assessments
BACKGROUND: Pre-eclampsia is a pregnancy complication affecting both mother and fetus. Although there is no proven effective method to prevent pre-eclampsia, early identification of women at risk of pre-eclampsia could enhance appropriate application of antenatal care, management and treatment. Very little is known about the cost effectiveness of these and other tests for pre-eclampsia, mainly because there is no clear treatment path. The aim of this study was to provide a comprehensive overview of the existing evidence on the health economics of screening, diagnosis and treatment options in pre-eclampsia. METHODS: We searched three electronic databases (PubMed, EMBASE and the Cochrane Library) for studies on screening, diagnosis, treatment or prevention of pre-eclampsia, published between 1994 and 2014. Only full papers written in English containing complete economic assessments in pre-eclampsia were included. RESULTS: From an initial total of 138 references, six papers fulfilled the inclusion criteria. Three studies were on the cost effectiveness of treatment of pre-eclampsia, two of which evaluated magnesium sulphate for prevention of seizures and the third evaluated the cost effectiveness of induction of labour versus expectant monitoring. The other three studies were aimed at screening and diagnosis, in combination with subsequent preventive measures. The two studies on magnesium sulphate were equivocal on the cost effectiveness in non-severe cases, and the other study suggested that induction of labour in term pre-eclampsia was more cost effective than expectant monitoring. The screening studies were quite diverse in their objectives as well as in their conclusions. One study concluded that screening is probably not worthwhile, while two other studies stated that in certain scenarios it may be cost effective to screen all pregnant women and prophylactically treat those who are found to be at high risk of developing pre-eclampsia. DISCUSSION: This study is the first to provide a comprehensive overview on the economic aspects of pre-eclampsia in its broadest sense, ranging from screening to treatment options. The main limitation of the present study lies in the variety of topics in combination with the limited number of papers that could be included; this restricted the comparisons that could be made. In conclusion, novel biomarkers in screening for and diagnosing pre-eclampsia show promise, but their accuracy is a major driver of cost effectiveness, as is prevalence. Universal screening for pre-eclampsia, using a biomarker, will be feasible only when accuracy is significantly increased
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