Quantum Oscillations of Photocurrents in HgTe Quantum Wells with Dirac and Parabolic Dispersions

We report on the observation of magneto-oscillations of terahertz radiation induced photocurrent in HgTe/HgCdTe quantum wells (QWs) of different widths, which are characterized by a Dirac-like, inverted and normal parabolic band structure. The photocurrent data are accompanied by measurements of photoresistance (photoconductivity), radiation transmission, as well as magneto-transport. We develop a microscopic model of a cyclotron-resonance assisted photogalvanic effect, which describes main experimental findings. We demonstrate that the quantum oscillations of the photocurrent are caused by the crossing of Fermi level by Landau levels resulting in the oscillations of spin polarization and electron mobilities in spin subbands. Theory explains a photocurrent direction reversal with the variation of magnetic field observed in experiment. We describe the photoconductivity oscillations related with the thermal suppression of the Shubnikov-de Haas effect.Comment: 16 pages, 13 figure

How much does the time lag between wildlife field-data collection and LiDAR-data acquisition matter for studies of animal distributions? A case study using bird communities

Vegetation structure quantified by light detection and ranging (LiDAR) can improve understanding of wildlife occupancy and species-richness patterns. However, there is often a time lag between the collection of LiDAR data and wildlife data. We investigated whether a time lag between the LiDAR acquisition and field-data acquisition affected mapped wildlife distributions ranging from an individual species distribution to total avian species richness in a conifer forest. We collected bird and LiDAR data in 2009 across a 20,000 ha forest in northern Idaho. Using the 2009 LiDAR data, we modelled the probability of occurrence for the brown creeper (Certhia americana). Using the same 2009 LiDAR data, we additionally modelled total avian species richness and richness of three different bird nesting guilds (ground/understory, mid/upper canopy and cavity). We mapped brown creeper occupancy probability and species richness using the 2009 models, and then compared these maps with maps based on the same models applied to a 2003-LiDAR dataset. A prior study identified areas harvested between 2003 and 2009. There was on average a 5% absolute decrease in mapped probabilities of brown creeper occurrence in non-harvest areas between 2003 and 2009. Species richness changed by less than one species in all cases within non-harvest areas between the 2003 and 2009 maps. Although these comparisons were statistically significant at the p < 0.0001 level, it is likely that the high number of map cells (~480,000) influenced this result. Similar patterns between our 2003 and 2009 maps in non-harvest areas for this suite of avian responses suggests that a 6-year difference between field-data collection and LiDAR-data collection has a minimal effect on mapped avian patterns in an undisturbed coniferous forest. However, because this is one case study in one ecosystem, additional work examining the effect of temporal lags between LiDAR and field-data collection on mapping wildlife distributions is warranted in additional ecosystems

STRUCTURE OF METHYLPHEOPHORBIDE-RCI

he methanolic extract of the cyanobacterium (blue-green alga) Spirulina geitleri has been treated with methanolic acid to convert all chlorophyllous pigments to their methylpheophorbides. Fractionation of the latter from methylpheophorbide a by thin layer chromatography and high pressure liquid chromatography yielded methylpheophorbide-RCI. Its structure has been determined as 132S-hydroxy-20-chloro-methylpheophorbide a by 1H-nuclear magnetic resonance, absorption and circular dichroism spectroscopy, mass spectrometry and by partial synthesis from chlorophyll a. The pigment is isolated from Spirulina geitleri irrespective of the use or omission of chlorinated substances during the isolation procedure

The Role of Parvalbumin-positive Interneurons in Auditory Steady-State Response Deficits in Schizophrenia

© The Author(s) 2019. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.Despite an increasing body of evidence demonstrating subcellular alterations in parvalbumin-positive (PV+) interneurons in schizophrenia, their functional consequences remain elusive. Since PV+ interneurons are involved in the generation of fast cortical rhythms, these changes have been hypothesized to contribute to well-established alterations of beta and gamma range oscillations in patients suffering from schizophrenia. However, the precise role of these alterations and the role of different subtypes of PV+ interneurons is still unclear. Here we used a computational model of auditory steady-state response (ASSR) deficits in schizophrenia. We investigated the differential effects of decelerated synaptic dynamics, caused by subcellular alterations at two subtypes of PV+ interneurons: basket cells and chandelier cells. Our simulations suggest that subcellular alterations at basket cell synapses rather than chandelier cell synapses are the main contributor to these deficits. Particularly, basket cells might serve as target for innovative therapeutic interventions aiming at reversing the oscillatory deficits.Peer reviewe

Efficacy of boceprevir, an NS3 protease inhibitor, in combination with peginterferon alfa-2b and ribavirin in treatment-naive patients with genotype 1 hepatitis C infection (SPRINT-1): an open-label, randomised, multicentre phase 2 trial

Peginterferon plus ribavirin achieves sustained virological response (SVR) in fewer than half of patients with genotype 1 chronic hepatitis C virus infection treated for 48 weeks. We tested the efficacy of boceprevir, an NS3 hepatitis C virus oral protease inhibitor, when added to peginterferon alfa-2b and ribavirin. In part 1 of this trial, undertaken in 67 sites in the USA, Canada, and Europe, 520 treatment-naive patients with genotype 1 hepatitis C virus infection were randomly assigned to receive peginterferon alfa-2b 1·5 μg/kg plus ribavirin 800–1400 mg daily for 48 weeks (PR48; n=104); peginterferon alfa-2b and ribavirin daily for 4 weeks, followed by peginterferon alfa-2b, ribavirin, and boceprevir 800 mg three times a day for 24 weeks (PR4/PRB24; n=103) or 44 weeks (PR4/PRB44; n=103); or peginterferon alfa-2b, ribavirin, and boceprevir three times a day for 28 weeks (PRB28; n=107) or 48 weeks (PRB48; n=103). In part 2, 75 patients were randomly assigned to receive either PRB48 (n=16) or low-dose ribavirin (400–1000 mg) plus peginterferon alfa-2b and boceprevir three times a day for 48 weeks (low-dose PRB48; n=59). Randomisation was by computer-generated code, and study personnel and patients were not masked to group assignment. The primary endpoint was SVR 24 weeks after treatment. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00423670. Patients in all four boceprevir groups had higher rates of SVR than did the control group (58/107 [54%, 95% CI 44–64], p=0·013 for PRB28; 58/103 [56%, 44–66], p=0·005 for PR4/PRB24; 69/103 [67%, 57–76], p<0·0001 for PRB48; and 77/103 [75%, 65–83], p<0·0001 for PR4/PRB44; vs 39/104 [38%, 28–48] for PR48 control). Low-dose ribavirin was associated with a high rate of viral breakthrough (16/59 [27%]), and a rate of relapse (six of 27 [22%]) similar to control (12/51 [24%]). Boceprevir-based groups had higher rates of anaemia (227/416 [55%] vs 35/104 [34%]) and dysgeusia (111/416 [27%] vs nine of 104 [9%]) than did the control group. In patients with untreated genotype 1 chronic hepatitis C infection, the addition of the direct-acting antiviral agent boceprevir to standard treatment with peginterferon and ribavirin after a 4-week lead-in seems to have the potential to double the sustained response rate compared with that recorded with standard treatment alone. Merck