cssi/SciSciGPT-SciSciNet huggingface dataset:
Structural stability of lithium manganese oxides

We have studied stability of lithium-manganese oxides using density functional theory in the local density and generalized gradient approximation (GGA). In particular, the effect of spin-polarization and magnetic ordering on the relative stability of various structures is investigated. At all lithium compositions the effect of spin polarization is large, although it does not affect different structures to the same extent. At composition ${\mathrm{LiMnO}}_{2},$ globally stable Jahn-Teller distortions could only be obtained in the spin-polarized GGA approximation, and antiferromagnetic spin ordering was critical to reproduce the orthorhombic ${\mathrm{LiMnO}}_{2}$ structure as ground state. We also investigate the effect of magnetism on the Li intercalation potential, an important property for rechargeable Li batteries.
Sum-product theorem and exponential sum estimates in residue classes with modulus involving few prime factors

In this Note, we extend the results of Bourgain, Konyagin and Glibichuk to certain composite moduli q involving few ‘large’ primes. First a ‘sum-product’ theorem for subsets A of Zq is obtained, ensuring that |A+A|+|A.A|>c|A|1+ɛ provided |A|<q1−δ and A does not have a ‘large’ intersection with a translate of a subring. Next, exponential sum estimates are established. In particular nontrivial bounds are obtained for the exponential sums associated to a multiplicative subgroup H<Zq*, with applications to Heilbronn-type sums. To cite this article: J. Bourgain, M.-C. Chang, C. R. Acad. Sci. Paris, Ser. I 339 (2004).
Intracranial meningiomas: Analysis of recurrence after surgical treatment

Recurrence of intracranial meningiomas after surgery has long been recognized, but there is still no consensus about factors responsible for recurrence. To better understand such factors, we analysed data on 276 patients with meningiomas who were treated at our institution from 1976 to 1990 (mean follow-up=5.1 years). Effects of sex, tumour histology, tumour site, and radiotherapy on recurrence were closely studied. Using World Health Organization criteria to define malignancy, 254 of the tumours were benign and 22 were atypical or malignant. For data analysis, distinction was made between “recurrence” (i.e., reappearance of tumour after total resection) and “regrowth” (i.e., tumour enlargement after subtotal removal). Recurrence was seen in 2 of 183 benign meningiomas and in 10 of 16 malignant meningiomas. Recurrence and regrowth rates for malignant meningiomas far exceeded those for benign meningiomas (p=0.001). Neither sex nor tumour site was associated with subsequent recurrences in patients whose tumours had been completely resected.
A Linear Analysis of the Multiple Vortex Phenomenon in Simulated Tornadoes

Abstract A simple vertically-integrated axisymmetric model is used to Calculate axisymmetric flows for different swirl ratios(s) in tornado simulators. Thew axisymmetric states are then tested for stability using a primitive-equation linear model where the waves have both an azimuthal and a vertical wavenumber. For S high enough for there to be a central downdraft in the axisymmetric vortex, the vortex is unstable; otherwise it is stable. For relatively lows only azimuthal waves 1 and 2 are unstable, with wave 1 most unstable at lows followed by 2 at somewhat highers As S is further increased, the most unstable wave shifts to 4, then 5, and so forth. With some tuning, the model predicts the transitions from 0–1 and 1–2 secondary vortices to occur at about the observed value ofs Vertical wavelength are about 3 m, but they increase with increases There are two modes of instability: one in which only waves 1 or 2 are unstable and which appears at lows and a second mode where waves 4, 5 or 6 are most unstable...
Internal waves and turbulence in a stable stratified jet

Direct numerical simulations are performed to investigate the interaction between a stably stratified jet and internal gravity waves from an adjacent shear layer with mild stratification. Results from two simulations are presented: one with the jet located far from the shear layer (far jet) and the other with the shear layer right on top of the jet (near jet). The near jet problem is motivated by velocity and stratification profiles observed in equatorial undercurrents. In the far case, internal waves excited by the Kelvin–Helmholtz (K-H) rollers do not penetrate the jet. They are reflected and trapped in the region between the shear layer and the jet and lead to little dissipation. In the near case, internal waves with wavelength larger than that of the K-H rollers are found in and below the jet. Pockets of hot fluid, associated with horseshoe vortices that originate from the shear layer, penetrate into the jet region, initiate turbulence and disrupt the internal wave field. Coherent patches of enhanced dissipation moving with the mean velocity are observed. The dissipation in the stably stratified near jet is large, up to three orders of magnitude stronger than that in the propagating wave field or the jet of the far case.
Electrical Properties of Single Crystals, Bicrystals, and Polycrystals of MgO

The high oxygen pressure conductivity of high-purity single-crystal magnesium oxide at high temperatures varied as the 1/4 power of the oxygen partial pressure with a 3 eV activation energy; the low pressure conductivity varied as the -1/6 power of the pressure with an activation energy of 4 eV. The predominant defects proposed are (1) holes and singly ionized Mg vacancies at high pressure and (2) electrons and doubly ionized oxygen vacancies at low pressures. The effect of impurities was noted. Changes in the grain boundary conductance relative to the crystal conductance of MgO were observed as a function of temperature and pressure, but not as a function of grain boundary orientation, transport direction, or total impurity content. Increased high pressure ionic conductivity in polycrystalline material offered possible evidence for increased grain boundary diffusion.
Crystal Overgrowth on Gold Nanorods: Tuning the Shape, Facet, Aspect Ratio, and Composition of the Nanorods

Electrochemically prepared Au nanorods were used as seeds for the overgrowth of thin shells of gold, silver, and palladium by using a mild reducing agent, ascorbic acid, in the presence of surfactants at ambient condition. The unique crystal facets of the starting nanorods results in anisotropic crystal overgrowth. The overgrowth rates along different crystallographical directions can be further regulated by adding foreign ions or by using different metal reduction methods. This overgrowth study provides insights on how different metal ions could be reduced preferentially on different Au nanorod surfaces, so that the composition, aspect ratio, shape, and facet of the resulting nanostructures can be rationally tuned. These surfactant-stabilized bimetallic Au(core)M(shell) (M=Au, Ag, Pd) nanorod colloids might serve as better substrates in surface-enhanced Raman spectroscopy as well as exhibiting enhanced catalytic properties.
Dynamics of On-Street Parking in Large Central Cities

Parking is a critical component of transportation policy and management, especially for large central cities. Policies and management practices affecting parking in turn affect land use, air quality, traffic congestion, travel behavior, safety, economic development, and revenue. Yet effectively managing parking is an ongoing struggle for large central cities as they face competing objectives and ever-increasing demands for space. As important as parking is, relatively few serious analyses of parking exist, and even fewer of on-street or curb parking, which is of particular interest to central cities. FHWA funded a year-long study that included an extensive literature review, one-on-one discussions with city parking officials, a peer-to-peer exchange, and a questionnaire to which nine U.S. cities responded. The study was intended to describe comprehensively on-street parking policies and management practices in large cities and to identify best practices and areas for further research. Lessons learned include the following: to manage effectively, one must know what is being managed, yet many cities lack basic information about their parking resources; integration and coordination among agencies and divisions that manage parking is critical; and ongoing peer exchanges allow important information sharing to occur between cities.
'Cooling and cathing' the post-resuscitated

Cronier and co-workers provide additional evidence that routine use of mild therapeutic hypothermia combined with emergent coronary angiography and percutaneous intervention results in excellent survival with intact neurological function for post-resuscitation patients with ventricular fibrillation.
PARTICIPANT PERCEPTIONS OF A COMMUNITY COLLEGE SERVICE-LEARNING PROGRAM

Although the term “service-learning” was first used in 1966–67, service-learning has only been actively promoted by the American Association of Community Colleges since 1994. Johnson County Community College, a large, suburban community college located in Overland Park, Kansas, has had a formal service-learning program since 1993–94. To plan effectively for the future of the growing program, all faculty and staff participants since the program's inception were surveyed in 1999–2000 to collect basic information along with faculty and student perceptions of the program and to identify needed changes. Survey results revealed that program participants were well-satisfied with the program, although student respondents especially identified possible areas for change.
Two weeks of rifaximin relieves global symptoms and bloating in people with IBS without constipation.

Commentary on: M Pimentel, A Lembo, WD Chey, et al..; TARGET Study Group. Rifaximin therapy for patients with irritable bowel syndrome without constipation. N Engl J Med2011;364:22–32.
JWKB surface-wave seismograms on a laterally heterogeneous earth

SUMMARY A nymerically efficient implementation of JWKB theory is developed to calculate synthetic surface-wave seismograms on a smooth, laterally heterogeneous earth model. We illustrate the method by applying it to model SH12/WM13; the phase and amplitude anomalies of long-period, fundamental-mode Love and Rayleigh waves are compared with the corresponding results obtained using the great-circle approximation and first-order ray-perturbation theory, with the perturbations to the local eigenfunctions ignored. As expected, the most serious discrepancies between these two approximations and full JWKB theory occur for paths with large transverse phase-velocity gradients, which lead to significant deviations away from the source-receiver great circle. The great-circle approximation consistently underestimates the phase of the first-arriving G1 Love and R1 Rayleigh waves, in accordance with Fermat’s principle of least time. The global average Fermat bias is greater for Love than for Rayleigh waves; this may be partly responsible for the observed Love-Rayleigh discrepancy currently attributed to upper mantle transverse isotropy.