Negative surges in open channels: physical and numerical modeling

Negative surges can be caused by a sudden change in flow resulting from a decrease in water depth. In the present study, some physical experiments were conducted in a rectangular channel to characterize the unsteady free-surface profile and longitudinal velocity beneath a negative surge propagating upstream. The physical observations showed that, during the first initial instants, the celerity of the surge leading edge increased rapidly with time, while later the negative surge propagated upstream in a more gradual manner with a celerity decreasing slowly with increasing distance. The velocity data highlighted some relatively large turbulent fluctuations beneath the negative surge. The physical results were used to test the analytical solution of the Saint-Venant equations and some numerical models. The findings suggested that the negative surge propagation appeared relatively little affected by the boundary friction within the investigated flow conditions. DOI: 10.1061/(ASCE)HY.1943-7900.0000674. (C) 2013 American Society of Civil Engineers

SWIM: A Semi-Analytical Ocean Color Inversion Algorithm for Optically Shallow Waters

Ocean color remote sensing provides synoptic-scale, near-daily observations of marine inherent optical properties (IOPs). Whilst contemporary ocean color algorithms are known to perform well in deep oceanic waters, they have difficulty operating in optically clear, shallow marine environments where light reflected from the seafloor contributes to the water-leaving radiance. The effect of benthic reflectance in optically shallow waters is known to adversely affect algorithms developed for optically deep waters [1, 2]. Whilst adapted versions of optically deep ocean color algorithms have been applied to optically shallow regions with reasonable success [3], there is presently no approach that directly corrects for bottom reflectance using existing knowledge of bathymetry and benthic albedo.To address the issue of optically shallow waters, we have developed a semi-analytical ocean color inversion algorithm: the Shallow Water Inversion Model (SWIM). SWIM uses existing bathymetry and a derived benthic albedo map to correct for bottom reflectance using the semi-analytical model of Lee et al [4]. The algorithm was incorporated into the NASA Ocean Biology Processing Groups L2GEN program and tested in optically shallow waters of the Great Barrier Reef, Australia. In-lieu of readily available in situ matchup data, we present a comparison between SWIM and two contemporary ocean color algorithms, the Generalized Inherent Optical Property Algorithm (GIOP) and the Quasi-Analytical Algorithm (QAA)

SWIM: A Semi-Analytical Ocean Color Inversion Algorithm for Optically Shallow Waters

In clear shallow waters, light that is transmitted downward through the water column can reflect off the sea floor and thereby influence the water-leaving radiance signal. This effect can confound contemporary ocean color algorithms designed for deep waters where the seafloor has little or no effect on the water-leaving radiance. Thus, inappropriate use of deep water ocean color algorithms in optically shallow regions can lead to inaccurate retrievals of inherent optical properties (IOPs) and therefore have a detrimental impact on IOP-based estimates of marine parameters, including chlorophyll-a and the diffuse attenuation coefficient. In order to improve IOP retrievals in optically shallow regions, a semi-analytical inversion algorithm, the Shallow Water Inversion Model (SWIM), has been developed. Unlike established ocean color algorithms, SWIM considers both the water column depth and the benthic albedo. A radiative transfer study was conducted that demonstrated how SWIM and two contemporary ocean color algorithms, the Generalized Inherent Optical Properties algorithm (GIOP) and Quasi-Analytical Algorithm (QAA), performed in optically deep and shallow scenarios. The results showed that SWIM performed well, whilst both GIOP and QAA showed distinct positive bias in IOP retrievals in optically shallow waters. The SWIM algorithm was also applied to a test region: the Great Barrier Reef, Australia. Using a single test scene and time series data collected by NASA's MODIS-Aqua sensor (2002-2013), a comparison of IOPs retrieved by SWIM, GIOP and QAA was conducted

Additive and interaction effects at three amino acid positions in HLA-DQ and HLA-DR molecules drive type 1 diabetes risk.

Variation in the human leukocyte antigen (HLA) genes accounts for one-half of the genetic risk in type 1 diabetes (T1D). Amino acid changes in the HLA-DR and HLA-DQ molecules mediate most of the risk, but extensive linkage disequilibrium complicates the localization of independent effects. Using 18,832 case-control samples, we localized the signal to 3 amino acid positions in HLA-DQ and HLA-DR. HLA-DQβ1 position 57 (previously known; P = 1 × 10(-1,355)) by itself explained 15.2% of the total phenotypic variance. Independent effects at HLA-DRβ1 positions 13 (P = 1 × 10(-721)) and 71 (P = 1 × 10(-95)) increased the proportion of variance explained to 26.9%. The three positions together explained 90% of the phenotypic variance in the HLA-DRB1-HLA-DQA1-HLA-DQB1 locus. Additionally, we observed significant interactions for 11 of 21 pairs of common HLA-DRB1-HLA-DQA1-HLA-DQB1 haplotypes (P = 1.6 × 10(-64)). HLA-DRβ1 positions 13 and 71 implicate the P4 pocket in the antigen-binding groove, thus pointing to another critical protein structure for T1D risk, in addition to the HLA-DQ P9 pocket.This research utilizes resources provided by the Type 1 Diabetes Genetics Consortium, a collaborative clinical study sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institute of Allergy and Infectious Diseases (NIAID), National Human Genome Research Institute (NHGRI), National Institute of Child Health and Human Development (NICHD), and Juvenile Diabetes Research Foundation International (JDRF) and supported by U01 DK062418. This work is supported in part by funding from the National Institutes of Health (5R01AR062886-02 (PIdB), 1R01AR063759 (SR), 5U01GM092691-05 (SR), 1UH2AR067677-01 (SR), R01AR065183 (PIWdB)), a Doris Duke Clinical Scientist Development Award (SR), the Wellcome Trust (JAT) and the National Institute for Health Research (JAT and JMMH), and a Vernieuwingsimpuls VIDI Award (016.126.354) from the Netherlands Organization for Scientific Research (PIWdB). TLL was supported by the German Research Foundation (LE 2593/1-1 and LE 2593/2-1).This is the accepted manuscript. The final version is available at http://www.nature.com/ng/journal/v47/n8/full/ng.3353.html

Primjena fizikalnih i kemijskih metoda u uklanjanju mikotoksina iz hrane i hrane za životinje

Mikotoksini su sekundarni metaboliti plijesni koji predstavljaju značajan problem u području sigurnosti hrane te predstavljaju rizik za zdravlje te dobrobit ljudi i životinja. Učinkovitost metoda uklanjanja mikotoksina iz hrane i hrane za životinje, primarno žitarica kao najviše kontaminirane grupe hrane, ovisi o brojnim parametrima, od kojih su vrlo značajni svojstva onečišćenog materijala, odnosno njegov sastav, primarno sadržaj vode, te razina onečišćenja. Ovaj rad daje pregled fizikalnih i kemijskih metoda koje se manje ili više učinkovito mogu koristiti u tretmanu različitih vrsta hrane i hrane za životinje u cilju redukcije odnosno uklanjanja mikotoksina. Uklanjanje mikotoksina fizikalnim metodama uključuje njihovu ekstrakciju pomoću otapala, adsorpciju te toplinsku inaktivaciju ili inaktivaciju ozračivanjem. Najznačajnije metode su sortiranje po boji i gustoći, ljuštenje i mljevenje, flotacija, blanširanje, prženje, a u posljednje vrijeme vrlo značajna je primjena gama zračenja te hladne plazme. Uporabom kemijskih metoda koje podrazumijevaju primjenu kemikalija dolazi do konverzije mikotoksina u druge manje toksične spojeve, npr. kiseline, lužine, oksidanse, bisulfite i plinove, no moguća je konverzija i u toksičnije spojeve, što je još uvijek predmet brojnih istraživanja. Za razliku od fizikalnih metoda, kemijske metode uklanjanja mikotoksina u načelu se smatraju nepraktičnim i nepoželjnim, zbog uvjeta provedbe, stvaranja toksičnih ostataka te negativnog utjecaja na nutritivna, senzorska i funkcionalna svojstva proizvoda

Strong-coupling charge density wave in monolayer TiSe2

We study the 2 × 2 charge density wave (CDW) in epitaxially-grown monolayer TiSe2. Our temperature-dependent angle-resolved photoemission spectroscopy measurements indicate a strong-coupling instability, but reveal how not all states couple equally to the symmetry-breaking distortion, with an electron pocket persisting to low temperature as a non-bonding state. We further show how the CDW order can be suppressed by a modest doping of around 0.06(2) electrons per Ti. Our results provide an opportunity for quantitative comparison with a realistic tight-binding model, which emphasises a crucial role of structural aspects of the phase transition in understanding the hybridisation in the ground state. Together, our work provides a comprehensive understanding of the phenomenology of the CDW in TiSe2 in the 2D limit