Charging of Aggregate Grains in Astrophysical Environments

The charging of dust grains in astrophysical environments has been investigated with the assumption these grains are homogeneous spheres. However, there is evidence which suggests many grains in astrophysical environments are irregularly-shaped aggregates. Recent studies have shown that aggregates acquire higher charge-to-mass ratios due to their complex structures, which in turn may alter their subsequent dynamics and evolution. In this paper, the charging of aggregates is examined including secondary electron emission and photoemission in addition to primary plasma currents. The results show that the equilibrium charge on aggregates can differ markedly from spherical grains with the same mass, but that the charge can be estimated for a given environment based on structural characteristics of the grain. The "small particle effect" due to secondary electron emission is also important for determining the charge of micron-sized aggregates consisting of nano-sized particles.Comment: 9 figures. arXiv admin note: substantial text overlap with arXiv:1107.028

Modeling Agglomeration of Dust Particles in Plasma

The charge on an aggregate immersed in a plasma environment distributes itself over the aggregate's surface; this can be approximated theoretically by assuming a multipole distribution. The dipole-dipole (or higher order) charge interactions between fractal aggregates lead to rotations of the grains as they interact. Other properties of the dust grains also influence the agglomeration process, such as the monomer shape (spherical or ellipsoidal) or the presence of magnetic material. Finally, the plasma and grain properties also determine the morphology of the resultant aggregates. Porous and fluffy aggregates are more strongly coupled to the gas, leading to reduced collisional velocities, and greater collisional cross sections. These factors in turn can determine the growth rate of the aggregates and evolution of the dust cloud. This paper gives an overview of the numerical and experimental methods used to study dust agglomeration at CASPER and highlights some recent results

Entropy and information in neural spike trains: Progress on the sampling problem

The major problem in information theoretic analysis of neural responses and other biological data is the reliable estimation of entropy--like quantities from small samples. We apply a recently introduced Bayesian entropy estimator to synthetic data inspired by experiments, and to real experimental spike trains. The estimator performs admirably even very deep in the undersampled regime, where other techniques fail. This opens new possibilities for the information theoretic analysis of experiments, and may be of general interest as an example of learning from limited data.Comment: 7 pages, 4 figures; referee suggested changes, accepted versio

Inert Dark Matter and Strong Electroweak Phase Transition

The main virtue of the Inert Doublet Model (IDM) is that one of its spinless neutral bosons can play the role of Dark Matter. Assuming that the additional sources of CP violation are present in the form of higher dimensional operator(s) we reexamine the possibility that the model parameters for which the right number density of relic particles is predicted are compatible with the first order phase transition that could lead to electroweak baryogenesis. We find, taking into account recent indications from the LHC and the constraints from the electroweak precision data, that for a light DM (40-60 GeV) particle and heavy almost degenerate additional scalars $H^\pm$ and $A^0$ this is indeed possible but the two parameters most important for the strength of the phase transition: the common mass of $H^\pm$ and $A^0$ and the trilinear coupling of the Higgs-like particle to DM are strongly constrained. $H^\pm$ and $A^0$ must weight less than $\sim440$ GeV if the inert minimum is to be the lowest one and the value of the coupling is limited by the XENON 100 data. We stress the important role of the zero temperature part of the potential for the strength of the phase transition.Comment: 15 pages, 5 figures, minor chnges, comment on h-->2gamma adde

Chromatic Illumination Discrimination Ability Reveals that Human Colour Constancy Is Optimised for Blue Daylight Illuminations

The phenomenon of colour constancy in human visual perception keeps surface colours constant, despite changes in their reflected light due to changing illumination. Although colour constancy has evolved under a constrained subset of illuminations, it is unknown whether its underlying mechanisms, thought to involve multiple components from retina to cortex, are optimised for particular environmental variations. Here we demonstrate a new method for investigating colour constancy using illumination matching in real scenes which, unlike previous methods using surface matching and simulated scenes, allows testing of multiple, real illuminations. We use real scenes consisting of solid familiar or unfamiliar objects against uniform or variegated backgrounds and compare discrimination performance for typical illuminations from the daylight chromaticity locus (approximately blue-yellow) and atypical spectra from an orthogonal locus (approximately red-green, at correlated colour temperature 6700 K), all produced in real time by a 10-channel LED illuminator. We find that discrimination of illumination changes is poorer along the daylight locus than the atypical locus, and is poorest particularly for bluer illumination changes, demonstrating conversely that surface colour constancy is best for blue daylight illuminations. Illumination discrimination is also enhanced, and therefore colour constancy diminished, for uniform backgrounds, irrespective of the object type. These results are not explained by statistical properties of the scene signal changes at the retinal level. We conclude that high-level mechanisms of colour constancy are biased for the blue daylight illuminations and variegated backgrounds to which the human visual system has typically been exposed

Quality of life in Type 1 (insulin-dependent) diabetic patients prior to and after pancreas and kidney transplantation in relation to organ function

Improvement of the quality of life in Type 1 (insulin-dependent) diabetic patients with severe late complications is one of the main goals of pancreas and/or kidney grafting. To assess the influences of these treatment modalities on the different aspects of the quality of life a cross-sectional study in 157 patients was conducted. They were categorized into patients pre-transplant without dialysis (n=29; Group A), pre-transplant under dialysis (n=44; Group B), post-transplant with pancreas and kidney functioning (n=31; Group C), post-transplant with functioning kidney, but insulin therapy (n=29; Group D), post-transplant under dialysis and insulin therapy again (n=15; Group E) and patients after single pancreas transplantation and rejection, with good renal function, but insulin therapy (n=9; Group F). All patients answered a mailed, self-administered questionnaire (217 questions) consisting of a broad spectrum of rehabilitation criteria. The results indicate a better quality of life in Groups C and D as compared to the other groups. In general the scores are highest in C, but without any significant difference to D. Impressive significant differences between C or D and the other groups were found especially in their satisfaction with physical capacity, leisure-time activities or the overall quality of life. The satisfaction with the latter is highest in C (mean±SEM: 4.0±0.2 on a 1 to 5-rating scale; significantly different from A: 3.1±0.1, B: 2.7±0.2 and E: 2.6±0.3; p<0.01), followed by D (3.8±0.2; significantly different from B and E; p<0.01). Group F shows a mean of 3.1±0.4, which is not significantly different from C. The percentages of patients in each group, who are not working: A: 38 %, B: 64 %, C: 74 %, D: 66 %, E: 87 % and F: 78 % indicate that there is no marked improvement in the vocational situation after successful grafting

Mean population salt consumption in India: a systematic review

Background: Member states of the WHO, including India, have adopted a target 30% reduction in mean population salt consumption by 2025 to prevent noncommunicable diseases. Our aim was to support this initiative by summarizing existing data that describe mean salt consumption in India. Method: Electronic databases – MEDLINE via Ovid, EMBASE, CINAHL and the Cochrane Database of Systematic Reviews – were searched up to November 2015 for studies that reported mean or median dietary salt intake in Indian adults aged 19 years and older. Random effects meta-analysis was used to obtain summary estimates of salt intake. Results: Of 1201 abstracts identified, 90 were reviewed in full text and 21 were included: 18 cross-sectional surveys (n = 225 024), two randomized trials (n = 255) and one case–control study (n = 270). Data were collected between 1986 and 2014, and reported mean salt consumption levels were between 5.22 and 42.30 g/day. With an extreme outlier excluded, overall mean weighted salt intake was 10.98 g/day (95% confidence interval 8.57–13.40). There was significant heterogeneity between the estimates for contributing studies (I2 = 99.97%) (P homogeneity ≤0.001), which was likely attributable to the different measurement methods used and the different populations studied. There was no evidence of a change in intake over time (P trend = 0.08). Conclusion: The available data leave some uncertainty about exact mean salt consumption in India but there is little doubt that population salt consumption far exceeds the WHO-recommended maximum of 5 g per person per day

Salt intake and iodine status of women in Samoa

The objective of this study was to determine iodine nutrition status and whether iodine status differs across salt intake levels among a sample of women aged 18-45 years living in Samoa. A cross-sectional survey was completed and 24-hr urine samples were collected and assessed for iodine (n=152) and salt excretion (n=119). The median urinary iodine concentration (UIC) among the women was 88 &mu;g/L (Interquartile range (IQR)=54-121 &mu;g/L). 62% of the women had a UIC &lt;100 &mu;g/L. The crude estimated mean 24-hr urinary salt excretion was 6.6 (standard deviation 3.2) g/day. More than two-thirds (66%) of the women exceeded the World Health Organization recommended maximum level of 5 g/day. No association was found between median UIC and salt excretion (81 &mu;g/L iodine where urinary salt excretion &gt;=5 g/day versus 76 &mu;g/L where urinary salt excretion &lt;5 g/day; p=0.4). Iodine nutrition appears to be insufficient in this population and may be indicative of iodine deficiency disorders in Samoan women. A collaborative approach in monitoring iodine status and salt intake will strengthen both programs and greatly inform the level of iodine fortification required to ensure optimal iodine intake as population salt reduction programs take effect