ALBERT

Description: The role of the nuclear receptor TLX in hippocampal neurogenesis and cognition has just begun to be explored. In this study, we generated a transgenic mouse model that expresses TLX under the control of the promoter of nestin, a neural precursor marker. Transgenic TLX expression led to mice with enlarged...

Description: Author(s): G. Sun, G. Jackeli, L. Santos, and T. Vekua Ultracold dipolar spinor fermions in zig-zag–type optical lattices can mimic spin-orbital models relevant in solid-state systems, as transition-metal oxides with partially filled d levels, with the interesting advantage of reviving the quantum nature of orbital fluctuations. We discuss two different... [Phys. Rev. B 86, 155159] Published Wed Oct 31, 2012

Description: Author(s): F. Amiri, G. Sun, H.-J. Mikeska, and T. Vekua The ground-state phase diagram of a Heisenberg spin − 1 2 system on a two-leg ladder with rung alternation is studied by combining analytical approaches with numerical simulations. For the case of ferromagnetic leg exchanges a unique ferrimagnetic ground state emerges, whereas for the case of antiferro… [Phys. Rev. B 92, 184421] Published Fri Nov 20, 2015

Description: We present a study of the physical properties of the disc and tail of ESO137–001, a galaxy suffering from extreme ram-pressure stripping during its infall into the Norma cluster. With sensitive and spatially resolved MUSE (Multi Unit Spectroscopic Explorer) spectroscopy, we analyse the emission line diagnostics in the tail of ESO137–001, finding high values of [N ii ]/Hα and [O i ]/Hα that are suggestive of the presence of shocks in turbulent gas. However, the observed line ratios are not as strong as commonly seen in pure shock heating models, suggesting that other emission mechanisms may contribute to the observed emission. Indeed, part of the observed emission, particularly at close separations from the galaxy disc, may originate from recombination of photoionized gas stripped from the main body of ESO137–001. We also identify a large number of bright compact knots within in the tail, with line ratios characteristic of H ii regions. These H ii regions, despite residing in a stripped gas tail, have quite typical line ratios, densities, temperatures, and metallicity (~0.7 solar). The majority of these H ii regions are embedded within diffuse gas from the tail, which is dynamically cool ( ~ 25–50 km s – 1 ). This fact, together with a lack of appreciable gradients in age and metallicity, suggests that these H ii regions formed in situ . While our analysis represents a first attempt to characterize the rich physics of the ESO137–001 tail, future work is needed to address the importance of other mechanisms, such as thermal conduction and magnetohydrodynamic waves, in powering the emission in the tail.

Description: The Central Asian orogenic belt formed by accretion subsequent to the contraction of the paleo–Asian Ocean, and its southeastern segment terminated along the Solonker suture zone, amalgamating the Mongolian arcs and the North China craton by the end of the Early Triassic. Since typical regional collisional features are absent, its tectonic evolution remains speculative. An investigation into the variability of detrital zircon U-Pb ages and Hf ratios in Permian strata along a southeast-northwest transect from the Mongolian arcs to the North China craton reveals distinct differences: Northern basins carry a broad Mesoproterozoic to latest Precambrian age signature, and their sedimentary source terranes are of mixed juvenile to crustal magmatic origin. In contrast, southern basins contain detritus from the North China craton, and their sources are of dominantly crustal contaminated magmatic origin. Provenance analysis suggests that in the early Paleozoic (ca. 429 Ma), the paleo–Asian Ocean was consumed along the Uliastai arc and the North China craton, initiating the formation of the northern and southern accretionary orogens, respectively. By the end of the middle Carboniferous, the Mongolian arcs were consolidated after the accretion of the Uliastai arc. In the late Carboniferous (ca. 314 Ma), the Hegenshan back-arc basin opened, detaching the northern accretionary orogen. While subduction continued there, it may have temporarily ceased in the south after the accretion of a microcontinent (ca. 300 Ma). By the end of the Middle Permian (ca. 269 Ma), back-arc basin closure led to the formation and obduction of the suprasubduction zone Hegenshan ophiolite. Eventually, the paleo–Asian Ocean closed by double-sided subduction. Such accretionary wedge-wedge collision would not involve continental deep subduction, unlike other continental collisions. The early stages of the sequence likely resembled a Pacific-type scenario dominated by the subduction of oceanic lithosphere, including a Japanese Sea–type back-arc basin opening. The late stages involved the accretion of large-scale continental blocks, ultimately leading to final ocean closure, which may be similar to the archipelago-type setting of present-day Southeast Asia.

Description: Author(s): T. Vekua and G. Sun Exact asymptotic expressions of the uniform parts of the two-point correlation functions of bilinear spin operators in the Heisenberg antiferromagnetic spin- 1 2 chain are obtained. Apart from the algebraic decay, the logarithmic contribution is identified, and the numerical prefactor is determined. W… [Phys. Rev. B 94, 014417] Published Thu Jul 14, 2016

Description: Organic Letters DOI: 10.1021/acs.orglett.6b01618

Description: We report an investigation on the absorption mechanism of a GeSn photodetector with 2.4% Sn composition in the active region. Responsivity is measured and absorption coefficient is calculated. Square root of absorption coefficient linearly depends on photon energy indicating an indirect transition. However, the absorption coefficient is found to be at least one order of magnitude higher than that of most other indirect materials, suggesting that the indirect optical absorption transition cannot be assisted only by phonon. Our analysis of absorption measurements by other groups on the same material system showed the values of absorption coefficient on the same order of magnitude. Our study reveals that the strong enhancement of absorption for the indirect optical transition is the result of alloy disorder from the incorporation of the much larger Sn atoms into the Ge lattice that are randomly distributed.

Description: Author(s): G. Sun, J. Jaramillo, L. Santos, and T. Vekua We study the ground-state phase diagram of two-component fermions loaded in a ladderlike lattice at half filling in the presence of spin-orbit coupling. For repulsive fermions with unidirectional spin-orbit coupling along the legs we identify a Néel state which is separated from rung-singlet and fer... [Phys. Rev. B 88, 165101] Published Wed Oct 02, 2013

Description: Water availability is one of the key environmental factors that control ecosystem functions in temperate forests. Changing climate is likely to alter the ecohydrology and other ecosystem processes that affect forest structures and functions. We constructed a multi-year water budget (2004–2010) and quantified environmental controls on an evapotranspiration (ET) in a 70-year-old mixed-oak woodland forest in northwest Ohio, USA. ET was measured using the eddy-covariance (EC) technique along with precipitation (P), soil volumetric water content (VWC), and shallow groundwater table fluctuation. Three biophysical models were constructed and validated to calculate potential ET (PET) for developing predictive monthly ET models. We found that the annual variability in ET was relatively stable and ranged from 578 mm in 2009 to 670 mm in 2010. In contrast, ET/P was more variable and ranged from 0.60 in 2006 to 0.96 in 2010. Mean annual ET/PET_FAO was 0.64 while mean annual PET_FAO/P was 1.15. Annual ET/PET_FAO was relatively stable, varying from 0.60 in 2005 to 0.72 in 2004. Soil water storage and shallow groundwater recharge during the non-growing season were essential in supplying ET during the growing season when ET exceeded P. Spring leaf area index (LAI), summer photosynthetically active radiation (PAR), and autumn and winter air temperatures (T a ) were the most significant controls of monthly ET. Moreover, LAI regulated ET during the whole growing season and higher temperatures increased ET even during dry periods. Our empirical modeling showed that the interaction of LAI and PET explained 〉90% of the variability in measured ET. Altogether we found that increases in T a and shifts in P distribution are likely to impact forest hydrology by altering shallow groundwater fluctuations, soil water storage, and ET and, consequently, alter the ecosystem functions of temperate forests. This article is protected by copyright. All rights reserved.