Midrapidity Lambda and Lambda(macro) production in Au+Au collisions at the square root of [s(NN)]=130 GeV

We report the first measurement of strange (Lambda) and antistrange (Lambda macro) baryon production from square root of [s(NN)]=130 GeV Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC). Rapidity density and transverse mass distributions at midrapidity are presented as a function of centrality. The yield of Lambda and Lambda; hyperons is found to be approximately proportional to the number of negative hadrons. The production of Lambda; hyperons relative to negative hadrons increases very rapidly with transverse momentum. The magnitude of the increase cannot be described by existing hadronic string fragmentation models alone.     

Azimuthal anisotropy of K(0)(S) and Lambda+Lambda production at midrapidity from Au+Au collisions at sqrt[s(NN)]=130 GeV

We report STAR results on the azimuthal anisotropy parameter v(2) for strange particles K(0)(S), Lambda, and Lambda at midrapidity in Au+Au collisions at sqrt[s(NN)]=130 GeV at the Relativistic Heavy Ion Collider. The value of v(2) as a function of transverse momentum, p(t), of the produced particle and collision centrality is presented for both particles up to p(t) approximately 3.0 GeV/c. A strong p(t) dependence in v(2) is observed up to 2.0 GeV/c. The v(2) measurement is compared with hydrodynamic model calculations. The physics implications of the p(t) integrated v(2) magnitude as a function of particle mass are also discussed.     

Disappearance of back-to-back high-pT hadron correlations in central Au+Au collisions at sqrt[s NN ] =200 GeV

Azimuthal correlations for large transverse momentum charged hadrons have been measured over a wide pseudorapidity range and full azimuth in Au+Au and p+p collisions at sqrt[s(NN)]=200 GeV. The small-angle correlations observed in p+p collisions and at all centralities of Au+Au collisions are characteristic of hard-scattering processes previously observed in high-energy collisions. A strong back-to-back correlation exists for p+p and peripheral Au+Au. In contrast, the back-to-back correlations are reduced considerably in the most central Au+Au collisions, indicating substantial interaction as the hard-scattered partons or their fragmentation products traverse the medium.     

Transverse-momentum and collision-energy dependence of high-pT hadron suppression in Au+Au collisions at ultrarelativistic energies

We report high statistics measurements of inclusive charged hadron production in Au+Au and p+p collisions at sqrt[s(NN)]=200 GeV. A large, approximately constant hadron suppression is observed in central Au+Au collisions for 5相似文献   

Historical and future dynamics of land use land cover and its drivers in Ajora-Woybo watershed,Omo-Gibe basin,Ethiopia

Land use land cover (LULC) dynamics have long been recognized as a significant driver of natural resource change. As a result, understanding the spatial and temporal variation of LULC in the watershed is essential for effective natural resource management and long-term development. This study attempts to analyze the dynamics and change drivers from 1990 to 2020 and predict the situation for 2035 and 2050 in the Ajora-Woybo watershed. ArcGIS 10.3 and ERDAS 2015 were used to analyze quantitative data from Landsat imagery. For supervised image classification, a Maximum-Likelihood classification algorithm was used. To identify driver variables, focus groups and key informants' interviews were done. TerrSet 18.31 software was used to predict LULC utilizing the Multi-Layer Perceptron Neural Network and Cellular Automata-Markov Chain models incorporated in Land Change Modeler. Six LULC classes were discovered: cultivated land, built-up, shrub land, forest land, bare land, and water body. Cultivated land, built-up area, and bare land have increased at the expense of shrub land and forest land over the last three decades. Trends in water bodies show both decreasing and increasing trends. According to the predicted outcomes, cultivated land, built-up and bare land has increased, while shrub land and forest land have declined. Finally, agricultural expansion, population growth, wood extraction, resettlement, urbanization, and lack of environmental consideration were identified as the major drivers of LULC change. The study demonstrated that there have been significant changes in the watershed LULC. As a result, reversing the predicted conditions is critical to ensuring the watershed long-term viability.     

Size effect on the structural and electronic properties of lead telluride clusters

Theoretical computations of (PbTe)_n (n = 21–45) clusters based on density functional theory have demonstrated that at cluster size of (PbTe)₂₂ there is a transition from the strong preference of fivefold coordination to sixfold coordination of lead and tellurium atoms. (PbTe)₂₄ cluster is the smallest tetragonal structure in which its central atoms have bulk‐like coordination. This quantum dot (QD) contains a single‐unit cell of lead telluride crystal, thus can be considered as an “infant crystal.” (PbTe)₃₂ cluster is a perfectly cubic cluster for which its inner (PbTe)₄ core enjoys bulk‐like coordination. This (PbTe)₄ core unit of (PbTe)₃₂ cubic cluster has exactly the same environment as a primitive cell of lead telluride crystal. The (PbTe)_8n, (n ≥ 3) clusters are the magic number species with bulk‐like structure such that (n = 3–5) the nanoblocks considered here (PbTe)₂₄, (PbTe)₃₂, and (PbTe)₄₀ clusters exhibiting bulk‐like structure that can be replicated to obtain the bulk crystal. The calculated dimensions of this special clusters provided a rubric for understanding the pattern of aggregation, that is, the creation of defined nanoblocks [(PbTe)_8n, (n ≥ 6)], when they were accumulated on an appropriate surface. It is evident that the QDs (PbTe)_8n, (n = 3–5) clusters show high stability compared to their neighboring clusters. This can also be seen from the second‐order energy difference, binding, and fragmentation energy graphs. © 2014 Wiley Periodicals, Inc.     

Microwave-Assisted Green Synthesis of Gold Nanoparticles Using Olibanum Gum (Boswellia serrate) and its Catalytic Reduction of 4-Nitrophenol and Hexacyanoferrate (III) by Sodium Borohydride

In this work we report straightforward, an economically viable, one-step microwave-assisted green synthesis of well stabilized gold nanoparticles (AuNPs) by reducing chloroauric acid with natural water soluble olibanum gum (Boswellia serrate). The olibanum gum acts as a dual role of reducing and capping agent for synthesis of AuNPs. The formation of AuNPs was confirmed using UV–Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy and electron diffraction. The results indicated that the synthesized NPs were well dispersed and spherical in shape had an average diameter of 3 ± 2 nm. The reaction parameters significantly affected the formation of NPs, as the concentration of gum and irradiation time increases the formation of NPs particles increases and size of particles are reduced. In addition, it has been shown that these olibanum gum capped AuNPs functioned as effective homogeneous catalyst for the reduction of two model reactions hexacyanoferrate(III) and 4-nitrophenol by sodium borohydride. The kinetic investigations were carried out at different amount of AuNPs and different temperatures.     

The amyloidogenicity of gelsolin is controlled by proteolysis and pH.

BACKGROUND: Normally, gelsolin functions in plasma as part of the actin-scavenging system to assemble and disassemble actin filaments. The Asp 187-->Asn (D187N) Asp 187-->Tyr (D187Y) gelsolin mutations facilitate two proteolytic cuts in the parent protein generating a 71-residue fragment that forms amyloid fibrils in humans, putatively causing Finnish type familial amyloidosis (FAF). We investigated the role of the D187N mutation in amyloidogenicity using biophysical studies in vitro. RESULTS: Both the recombinant wild-type and D187N FAF-associated gelsolin fragments adopt an ensemble of largely unfolded structures that do not self-associate into amyloid at pH 7. 5. Incubation of either fragment at low pHs (6.0-4.0) leads to the formation of well-defined fibrils within 72 hours, however. CONCLUSIONS: The D187N mutation has been suggested to destabilize the structure of the gelsolin parent protein (specifically domain 2), facilitating two proteolytic cleavage events. Our studies demonstrate that generating the largely unstructured peptide is not sufficient alone for amyloid formation in vitro (on a time scale of months). A drop in pH or an analogous environmental change appears necessary to convert the unstructured fragment into amyloid fibrils, probably through an associative mechanism. The wild-type gelsolin fragment will make amyloid fibrils from pH 6 to 4 in vitro, but neither the wild-type fragment nor fibrils have been observed in vivo. It is possible that domain 2 of wild-type gelsolin is stable in the context of the whole protein and not susceptible to the proteolytic degradation that affords the 71-residue FAF-associated peptide.     

Centrality dependence of high-p(T) hadron suppression in Au+Au collisions at sqrt[s(NN)]=130 GeV

Inclusive transverse momentum distributions of charged hadrons within 0.2相似文献