2,200 research outputs found
Groundwater sapping channels: Summary of effects of experiments with varied stratigraphy
Experiments in the recirculating flume sapping box have modeled valley formation by groundwater sapping processes in a number of settings. The effects of the following parameters on sapping channel morphology were examined: surface slope; stratigraphic variations in permeability cohesion and dip; and structure of joints and dikes. These kinds of modeling experiments are particularly good for: testing concepts; developing a suite of distinctive morphologies and morphometries indicative of sapping; helping to relate process to morphology; and providing data necessary to assess the relative importance of runoff, sapping, and mass wasting processes on channel development. The observations from the flume systems can be used to help interpret features observed in terrestrial and Martian settings where sapping processes are thought to have played an important role in the development of valley networks
Lifestyle interventions for people with, and at risk of type 2 diabetes in Polynesian communities : A systematic review and meta-analysis
There is evidence that lifestyle intervention among Polynesian people can reduce diabetes incidence and complications, but this evidence has not been systematically reviewed. The aim of this study was to systematically review the efficacy of lifestyle interventions, targeting the prevention and management of type 2 diabetes among Polynesian people. MEDLINE, Web of Science, Cochrane Library, and Embase were searched to find randomised controlled trials (RCTs) and pre-post studies. Eight studies (four RCTs and four pre-post studies) with 1590 participants met the inclusion criteria. The data on health outcomes that was reported in these studies included blood pressure, body mass index, waist circumference, weight, and glycated haemoglobin (HbA1c). The meta-analyses showed that the interventions had resulted in statistically significant reductions in systolic blood pressure (SBP) across four of the studies (WMD, â9.93 mmHg; 95% Cl, â10.77 to â9.09; and p < 0.00001). However, the effects on weight across five of the studies (WMD, â1.15 kg; 95% Cl, â2.80 to 0.51; p = 0.18) and the HbA1c levels across two of the studies (WMD, â0.38%; 95% Cl, â1.15 to 0.39; and p = 0.33) were not statistically significant. This review provides evidence that lifestyle interventions may be effective in achieving modest reductions in SBP in Polynesian people. Further research is needed to fully assess the effectiveness of these interventions in this population long-term
Comparisons Between Spectral Quality Metrics and Analyst Performance in Hyperspectral Target Detection
Quantitative methods to assess or predict the quality of a spectral image continue to be the subject of a number of current research activities. An accepted methodology would be highly desirable for use in data collection tasking or data archive searching in ways analogous to the current prediction of panchromatic image quality through the National Imagery Interpretation Rating Scale (NIIRS) using the General Image Quality Equation (GIQE). A number of approaches to the estimation of quality of a spectral image have been published, but most capture only the performance of automated algorithms applied to the spectral data. One recently introduced metric, however, the General Spectral Utility Metric (GSUM), provides for a framework to combine the performance from the spectral aspects together with the spatial aspects. In particular, this framework allows the metric to capture the utility of a spectral image resulting when the human analyst is included in the process. This is important since nearly all hyperspectral imagery analysis procedures include an analyst. To investigate the relationships between candidate spectral metrics and task performance from volunteer human analysts in conjunction with the automated results, simulated images are generated and processed in a blind test. The performance achieved by the analysts is then compared to predictions made from various spectral quality metrics to determine how well the metrics function. The task selected is one of finding a specific vehicle in a cluttered environment using a detection map produced from the hyperspectral image along with a panchromatic rendition of the image. Various combinations of spatial resolution, number of spectral bands, and signal-to-noise ratios are investigated as part of the effort
Jet Physics from Static Charges in AdS
Soft interactions with high-energy jets are explored in radial coordinates
which exploit the approximately conformal behavior of perturbative gauge
theories. In these coordinates, the jets, approximated by Wilson lines, become
static charges in Euclidean AdS. The anomalous dimension of the corresponding
Wilson line operator is then determined by the potential energy of the charges.
To study these Wilson lines we introduce a "conformal gauge" which does not
have kinetic mixing between radial and angular directions, and show that a
number of properties of Wilson lines are reproduced through relatively simple
calculations. For example, certain non-planar graphs involving multiple Wilson
lines automatically vanish. We also discuss the linear growth of the charges'
imaginary potential energy with separation, and a relationship between Wilson
line diagrams and Witten diagrams.Comment: 34 pages, 7 figures; V2: minor edits, added reference
Quantum authentication with unitary coding sets
A general class of authentication schemes for arbitrary quantum messages is
proposed. The class is based on the use of sets of unitary quantum operations
in both transmission and reception, and on appending a quantum tag to the
quantum message used in transmission. The previous secret between partners
required for any authentication is a classical key. We obtain the minimal
requirements on the unitary operations that lead to a probability of failure of
the scheme less than one. This failure may be caused by someone performing a
unitary operation on the message in the channel between the communicating
partners, or by a potential forger impersonating the transmitter.Comment: RevTeX4, 10 page
Evidence for guild structure in hyperdiverse mammalian communities.
43 pages : 1 map ; 26 cm.The ecological mechanisms that sustain high species richness in Neotropical bat communities have attracted research attention for several decades. Although many ecologists have studied the feeding behavior and diets of Neotropical bats on the assumption that food is a limiting resource, other resource axes that might be important for species coexistence are often ignored. Diurnal refugia, in particular, are a crucial resource for bats, many of which exhibit conspicuous morphological or behavioral adaptations to the roost environment. Here we report and analyze information about roost occupancy based on >500 field observations of Amazonian bats. Statistical analyses of these data suggest the existence of distinct groups of species roosting (1) in foliage, (2) exposed on the trunks of standing trees, (3) in cavities in standing trees, (4) in or under fallen trees, (5) beneath undercut earth banks, and (6) in arboreal insect nests; additionally, we recognize other groups that roost (7) in animal burrows, and (8) in rocks or caves. Roosting-guild membership is hypothesized to have a filtering effect on Amazonian bat community composition because some types of roosts are absent or uncommon in certain habitats. Among other applications of our results, cross-classifying bat species by trophic and roosting guilds suggests that the often-reported deficit of gleaning animalivores in secondary vegetation by comparison with primary forest might reflect habitat differences in roost availability rather than food resources. In general, ecological and evolutionary studies of Neotropical bats would be enhanced by considering both trophic- and roosting-guild membership in future analyses, but additional fieldwork will be required to determine the roosting behavior of many data-deficient species
New species of Hsunycteris.
26 pages : illustrations (some color), map ; 26 cm.A new species of the nectarivorous bat genus Hsunycteris is described from lowland Amazonian forest in northeastern Peru. The new species, H. dashe, can be distinguished from other congeners by its larger size; V-shaped array of dermal chin papillae separated by a wide basal cleft; metacarpal V longer than metacarpal IV; broad rostrum; lateral margin of infraorbital foramen not projecting beyond rostral outline in dorsal view; well-developed sphenoidal crest; large outer upper incisors; weakly developed lingual cusp on P5; and well-developed, labially oriented M1 parastyle. A phylogenetic analysis of cytochrome-b sequence data indicates that H. dashe is sister to a clade that includes all other species of the genus including H. cadenai, H. pattoni, and a paraphyletic H. thomasi. We provide a key based on craniodental and external characters of all four known species of Hsunycteris
Immune function during early adolescence positively predicts adult facial sexual dimorphism in both men and women
Evolutionary theories suggest that humans prefer sexual dimorphism in faces because masculinity in men and femininity in women may be an indicator of immune function during development. In particular, the immunocompetence handicap hypothesis proposes that sexual dimorphism indicates good immune function during development because the sex hormones, particularly testosterone in men, required for the development of sexually dimorphic facial features also taxes the immune system. Therefore, only healthy males can afford the high level of testosterone for the development of sexually dimorphic traits without compromising their survival. Researchers have suggested that a similar mechanism via the effects of oestrogen might also explain male preferences for female femininity. Despite the prominence of the immunocompetence handicap hypothesis, no studies have tested whether immune function during development predicts adult facial sexual dimorphism. Here, using data from a longitudinal public health dataset, the Western Australian Pregnancy Cohort (Raine) Study (Generation 2), we show that some aspects of immune function during early adolescence (14âŻyears) positively predict sexually dimorphic 3D face shape in both men and women. Our results support a fundamental assumption that facial sexual dimorphism is an indicator of immune function during the development of facial sexual dimorphism.PostprintPeer reviewe
The relationship between self-reported sensory experiences and autistic traits in the general population:a mixed methods analysis
There have been few examples of inductive research in sensory reactivity, particularly in relation to autistic traits among the general population. This study used a mixed methods approach to explore the nature of sensory experiences among people with different levels of autistic traits. Participants completed the Glasgow Sensory Questionnaire and the Autism Spectrum Quotient. Both quantitative and qualitative analyses were performed on the data. Responses to the open questions were analyzed as part of this study, and the closed questionnaire data have been reported elsewhere. Data were coded and responses quantitatively compared by group. In addition, data were qualitatively analyzed using a general inductive approach, which resulted in two themes: âproblematic sensory experiencesâ and âcalming sensory experiences.â Results show that coping mechanisms and certain aspects of the sensory experience vary according to autistic trait level, and provide insight into the nature of sensory reactivity across the general population
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