Miracle-dz/UniFAR-FTUs huggingface dataset:
Spectroscopic study of dark excitons in In x Ga 1-x As self-assembled quantum dots by a magnetic-field-induced symmetry breaking

The dark states of the heavy-hole ground-state exciton have been studied by photoluminescence spectroscopy of single self-assembled ${\mathrm{In}}_{0.60}{\mathrm{Ga}}_{0.40}\mathrm{As}$ quantum dots in magnetic fields of varying strengths and orientations. When tilting B out of the [001] crystal direction the exciton states with angular momenta $|m|=2$ are mixed with the $|m|=1$ states and become observable. In combination with a detailed analysis of the corresponding Hamiltonian a comprehensive picture of the exciton fine structure is obtained. This fine structure is characteristic for direct gap semiconductors with a twofold degenerate valence band.
Estimation of the Kelvin Wave Contribution to the Semiannual oscillation.

Abstract The behavior of Kelvin waves in the equatorial middle atmosphere is investigated with the use of daily mapped temperature derived from the Limb Infrared Monitor of the Stratosphere (LIMS) experiment. Diagrams of wave activity per unit mass and wave activity flux density concisely illustrate bulk properties of Kelvin waves and facilitate tracing of packets to source times near the tropopause. Kelvin wave packets of different zonal wavenumbers propagate separately and appear to be forced separately. During the LIMS data period (25 October 1978–28 May 1979) two Kelvin wave regimes are found. Packets of wave one, wave two, or wave three Kelvin waves occur at irregular intervals prior to April. During April and May a nearly continuous upward flux of wave one activity dominates. For very tall Kelvin waves the observed dependence of vertical wavelength on zonal wind is weaker than predicted by the slowly-varying theory for internal gravity waves. However, most properties of the observed waves are consis.
Relaxation of the magnetization in uniaxial single-domain ferromagnetic particles driven by a strong ac magnetic field

The magnetization spectrum and reversal time of uniaxial single-domain ferromagnetic particles driven by an ac magnetic field of arbitrary strength applied along the easy axis are evaluated by solving the infinite hierarchy of recurrence equations for the Fourier components of the relaxation functions governing the frequency dependence of the magnetization. A simple analytic equation for the reversal time is also obtained via the mean first passage time method exhibiting pronounced nonlinear effects such as a rapid decrease in the reversal time as the strength of the ac field increases. For weak ac fields, the results agree with perturbation theory.
The Evolution of Galaxies. II. Chemical Evolution Coefficients

We present a detailed analysis of how stellar evolution determines the coefficients in theories of the chemical evolution of galaxies. With these coefficients, it is possible to make comparisons with observed abundances; these comparisons are insensitive to the history of the total stellar birthrate. From a detailed examination of numerical stellar evolutionary sequences we evaluate these coefficients. The agreement with observation is excellent.
Canonical transformation and accidental degeneracy. III. A unified approach to the problem

We continue the discussion of the groups of canonical transformations responsible for accidental degeneracy in quantum mechanical problems. A general unified treatment is provided for a wide class of two−dimensional physical systems, having an energy spectrum which is a linear combination of two quantum numbers. The general method involves the use of both nonorthonormal and orthonormal sets of states to construct groups of complex or real canonical transformations, mapping the problem under consideration onto the two−dimensional isotropic harmonic oscillator. The group responsible for the accidental degeneracy is then quite obviously SU (2). The problem of an isotropic oscillator in a sector π/q (q integer) was discussed previously using a nonorthonormal basis. In the present paper we carry the analysis in an orthonormal basis to establish the general procedure mentioned above. We also analyze in detail the Calogero problem for three particles which has a spectrum of the type given above, and obtain expli.
Coherent transient phenomena in quantum systems by spatially shaping femtosecond optical pulses

Providing a femtosecond optical pulse with a proper transverse spatial profile represents a fast and relatively simple method to force a quantum system to follow a prescribed temporal evolution. In the present work, we show that the quantum system presents a surprisingly high sensitivity with respect to the spatial shape of the pulse. We discuss an explicit example where differences on the order of a few nanometers in the initial pulse’s spot size induce completely different responses in the system under study.
Spatial Smoothing of Geographically Aggregated Data, with Application to the Construction of Incidence Maps

Abstract We address the commonly encountered situation in spatial statistics where data such as counts of incidences of a certain disease are available only in geographically aggregated form. We develop fairly general models and propose a modified version of the locally weighted least squares method to recover the unknown smooth spatial function that is assumed to generate the observations. In the special case of count data, the target function is the intensity function, conditional on the total number of observations. Our method avoids the arbitrariness of selecting a point within each geographic area at which the measurement for the whole area is supposed to be located. We derive basic asymptotic properties, and apply our methods to acquired immune deficiency syndrome (AIDS) incidence data in San Francisco for 1980–1992, where counts are available aggregated over zip code areas.
Magnetic relaxation and flux pinning in YBCO films prepared by PLD from a nanocrystalline target

The magnetic flux pinning properties of YBCO films prepared by pulsed laser deposition from nano- (n) and microcrystalline (μ) targets are studied and compared by magnetic relaxation and hysteresis measurements. The most striking difference between the films is the higher critical current density of the n-films (Jc(0 T,77 K) = 1 × 107 A cm−2) compared to the μ-films (Jc(0 T,77 K) = 3 × 106 A cm−2). The accommodation field B* that determines the end of the low field plateau of Jc is three times higher in the n-film than in the μ-film. In higher fields Jc(B) follows a power-law behaviour with exponents α = −0.6 in the intermediate field region and −2 in the high fields. The results are discussed on the basis of the recent strong pinning theories and it is concluded that the observed stronger pinning in the n-film is due to higher density of extended defects.
Overvoltage Robustness of p-Gate GaN HEMTs in High Frequency Switching up to Megahertz

This article investigates the ruggedness of the GaN high electron mobility transistor (HEMT), a power device without avalanche capability, in continuous, high-frequency, overvoltage switching. A testbed based on a zero-voltage-switched converter with an active clamping circuit is developed to enable the stable switching with kilovolt overvoltage and megahertz frequency. The overvoltage failure boundaries and mechanisms of four commercial p-gate GaN HEMTs from multiple vendors are explored. Besides the electrical failure at the dynamic breakdown voltage (BVDYN), two new failure mechanisms are observed in some devices. One mechanism features a drastic, nearly unrecoverable on-resistance increase, leading to conduction loss ramp-up and thermal failure. The other mechanism exhibits an increase in drain leakage current and a catastrophic breakdown at lower blocking voltage. Both mechanisms are found to occur only at high frequency (>100 kHz) and decrease the BVDYN by at least 30%, and they can be attributed to the serious carrier trapping in GaN HEMTs under the high-frequency overvoltage switching. Finally, we provide a simple method for device users to filter out devices with these extrinsic failure mechanisms and identify the intrinsic BVDYN of GaN HEMTs, which deploys a simple unclamped inductive switching circuit. These results provide critical reference for the protection and qualification of GaN power HEMTs.
The Status of Extended-spectrum β-lactamase and AmpC β-lactamase production in uropathogenic isolates of Escherichia coli and Klebsiella pneumonia in Bangladesh

Background: The rapid dissemination of antibiotic resistance as extended-spectrum beta-lactamases (ESBLs) and AmpC β-lactamases in bacteria became a major public health concern worldwide. Hence, this study was carried out to evaluate the status of uropathogenic isolates of Bangladesh especially Escherichia coli and Klebsiella pneumoniae in terms of ESBL and AmpC β-lactamases enzymes production. Methods: A laboratory-based cross-sectional survey was conducted with 553 urine samples at the Department of Microbiology, Popular Diagnostic Centre Ltd. Dhaka, Bangladesh for a period of 2.5 years from July 2017 to December 2019. Pathogens were obtained upon culture, and screened for ESBL production following the cephalosporin disk diffusion method and cephalosporin-clavulanate combination disc test (confirmatory) method. For AmpC β-lactamases enzymes, cefoxitin disc diffusion, and AmpC disc test (confirmatory) methods were performed. The positive isolates were further genotyped for the presence of blaTEM, blaSHV, blaOXA, and blaCTX-M β-lactamases genes in case of ESBL and blaFOX, blaCMY, and blaDHA genes for AmpC β-lactamases by polymerase chain reaction. Results: Of all urine samples, uropathogens were detected among 28.57% (158, n=553) samples. Among them, 46.20% (73) were E. coli and 20.25% (32) were K. pneumoniae. The prevalence of ESBL and AmpC β-lactamases production in E. coli was 34.24% (25) and 17.80% (13) respectively whereas it was 43.75% (14) and 21.87% (7) in Klebsiella pneumoniae isolates respectively. These resistance properties were further confirmed by phenotypic disc test. In case of ESBLs, most typical isolates possessed two or more resistance genes. Overall, the most prevalent gene was blaCTX-M (84.61%) followed by blaTEM (64.10%), blaOXA (46.15%) and blaSHV (25.64%). In case of AmpC β-lactamases FOX gene was most prevalent (45%) followed by CMY (20%) and DHA 3 (15%). Conclusion: The high prevalence of ESBL and AmpC β-lactamases production in our study emphasizes the judicious use of antibiotics in controlling urinary tract infections in Bangladesh.
A soft X-ray study of the Large Magellanic Cloud

A survey of the Large Magellanic Cloud (LMC) has been carried out with the imaging X-ray telescope aboard the Einstein Observatory. Ninety-seven sources were detected. On statistical grounds, we estimate that less than 25 of these are likely to be either foreground stars or background quasars. The remaining 75 sources which are in the LMC have luminosities ranging from 1 × 1035 to 2 × 1038 erg s−1 and are heavily concentrated around the HI complex surrounding the 30 Doradus nebula. At least 25 of the sources are supernova remnants (SNR), including six nebulae that had not been previously recognized as such. Of the remaining 50 sources, about half appear to be extended and are also likely to be SNR. High resolution observations of selected remnants indicate that SNR diameters in the LMC have been consistently underestimated by radio and optical observers, an effect that reduces previous estimates of the SNR rate. However, the X-ray observations also demonstrate that previous catalogs of LMC remnants suffer considerably from incompleteness. When both effects are considered, we derive a SN rate in the LMC of 1 per 110 to 340 years. The identity of the remaining survey sources is unclear. If they are not SNR, as well, they represent a class of objects heretofore unrecognized in the galaxy — point X-ray sources with luminosities between 1035 and 1036 erg s−1.
Robot non‐linearity bounds evaluation techniques for robust control

Robust controller design approaches for non-linear control systems usually require the evaluation of upper bounds on non-linear quantities of the process for the robustness analysis. The conservatism and usefulness of robustness criteria are determined by the accuracy of the robustness bounds. This contribution deals with the robust control of robot manipulators and presents generally applicable evaluation techniques for bounds on robot manipulator non-linearities which may be remnants of an incomplete non-linear decoupling or feedback linearization. These bounds can be used to verify several robust stability criteria for the control of rigid and elastic joint robots. Apparently, these bounds give insight to the strength and significance of non-linear couplings and may be used to judge whether complicated model-based control laws should be preferred rather than simple linear controllers.
Wind‐generated surface noise source levels in deep water east of Australia

Recordings of ambient sea noise from four deep water sites between Australia and New Zealand have been examined for correlation between the narrow‐band spectrum level and the observed local wind speed. Significant wind dependence is observed at all frequencies between 37 and 800 Hz. When the results are reprocessed to examine only locally generated noise (horizontally arriving sound from distant sources is rejected by making use of the directional properties of a steerable vertical hydrophone array), it is found that the wind dependence of the observed noise at low frequencies is significantly enhanced. The rate of increase of locally generated noise with wind speed is very similar to published values for Australian waters, except for frequencies below 100 Hz, and much lower than most reported measurements in northern hemisphere waters. By steering upward‐looking beams, the levels of sound radiated (per steradian) from the surface, at various wind speeds, were measured. The measurements were adjusted, whe.
Galaxy merging in modified Newtonian dynamics

We present the results of N-body simulations of dissipationless galaxy merging in modified Newtonian dynamics (MOND). For comparison, we also studied Newtonian merging between galaxies embedded in dark matter haloes, with internal dynamics equivalent to the MOND systems. We found that the merging time-scales are significantly longer in MOND than in Newtonian gravity with dark matter, suggesting that observational evidence of rapid merging could be difficult to explain in MOND. However, when two galaxies eventually merge, the MOND merging end-product is hardly distinguishable from the final stellar distribution of an equivalent Newtonian merger with dark matter.
Absorption by airborne and deposited particles in the 8-13 micrometer range

The absorption of radiation by natural aerosol particles was measured in the 8–13 micrometer wavelength interval. A comparison was made between an in situ method and measurements of particles of deposited form. The results are in agreement to about 30 percent. The main feature of aerosol absorption within the infrared window is a strong absorption peak near 9 micrometers caused by sulfate or quartz particles present in all continental aerosol types. Consequences for the atmospheric heat balance are clear sky cooling rates growing from about 2 per cent in the tropics to about 20 per cent of the total cooling in arctic regions under normal conditions, additionally increasing with increasing relative humidity. DOI: 10.1111/j.2153-3490.1975. tb01706.x
A Mixed Models Approach to the Age-Period-Cohort Analysis of Repeated Cross-Section Surveys, with an Application to Data on Trends in Verbal Test Scores

We develop a mixed (fixed and random effects) models approach to the age-period-cohort (AFC) analysis of micro data sets in the form of a series of the repeated cross-section sample surveys that are increasingly available to sociologists. This approach recognizes the multilevel structure of the individual-level responses. As a substantive illustration, we apply our proposed methodology to data on verbal test scores from 15 cross-sections of the General Social Survey, 1974–2000. These data have been the subject of recent debates in the sociological literature. We show how our approach can be used to shed new light on these debates by identifying and estimating age, period, and cohort components of change.
Green synthesis of silver nanoparticles through green caviar Caulerpa lentillifera and its phytotoxicity on Allium ascolanicum

Abstract Caulerpa lentillifera, one of the edible marine seaweeds, was used to synthesize silver nanoparticles (AgNPs) in this study. According to the results, optimum conditions such as initial biomass concentration, AgNO3 concentration, pH, temperature, agitation rate for the synthesis of AgNPs by using C. lentillifera were 0.01 g/mL, 8 mM AgNO3, pH 10, 85 °C and 0 rpm, respectively. The calculated particle sizes of the synthesized AgNPs were 22.3 nm. The characterizations of synthesized AgNPs were carried out through UV-Vis spectrophotometry, FT-IR and XRD. The development shoot and root of shallot (Allium ascalonicum) experiments were tested to evaluate the phytotoxicity of synthesized C. lentillifera-based AgNPs. The phytotoxic effect of C. lentillifera-based AgNPs was found to be dose dependent. Since the phytotoxicity of the AgNPs synthesized in the study is evaluated, its industrial applications in the food, medicine, pharmacy and agriculture industries can be further considered based on the usage doses.
Experimental Study of a Radial Turbulent Jet : 1st Report, Effect of Nozzle Shape on a Free Jet

Mean velocity and turbulence together with pressure distributions in a radial free jet flows were studied. By changing diameter and width of nozzles and discharge velocity, the flow pattern were measured. The concept of the equivalent nozzle width which contains the diameter and width of the nozzle can be usefully applied to describe both maximum flow velocity decay and growth of the jet half width with distance from a nozzle outlet. The maximum flow velocity decay and the growth of the jet half width lie on a single curve according to this equivalent nozzle width. In the main region at large nozzle Reynolds number, the maximum flow velocity decays following the same rule as in circular jet, and the growth of the jet half width is in good agreement with that in the two-dimensional jet.
$ \mathbb Q$-factorial quartic threefolds

It is proved that a? nodal quartic threefold? X containing no planes is -factorial if it has at most 12? singular points. An exception here is a? quartic with precisely 12? singularities containing a? quadric surface. Some geometric constructions relating to such a? quartic are presented. Bibliography: 14 titles.
Nanoscale precision in ion milling for optical and terahertz antennas

Plasmonics and nanoscale antennas have been intensively investigated for sensors, metasurfaces and optical trapping where light control at the nanoscale enables new functionalities. To confine and manipulate the light in tiny spaces sub-wavelength antennas should be used with dimensions from micro- to nano-meters and are still challenging to make. Direct fabrication/modification of nanostructures using focused ion beam (FIB) milling is demonstrated for several types of antennas. Arrays of identical nanoparticles were fabricated in a single step by (i) milling gold films or (ii) by modifying structures which were already defined by electron beam or mask projection lithography. Direct FIB writing enables to exclude resist processing steps, thus making fabrication faster and simpler. Sensor areas of 25x25 μm2 of densely packed nanoparticles separated by tens-of-nanometers were fabricated in half an hour (103 μm2/h throughput at 90 nm resolution). Patterns of chiral nanoparticles by groove inscription is demonstrated. The processing speed and capability to mill complex 3D surfaces due to depth of focus not compromised over micrometers length, makes it possible to reach sub-50 nm resolution of direct write. FIB technology is practical for emerging applications in nano-fabrication/photonic/fluidic/magnetic applications.
NUMERICAL EVALUATION OF ITERATIVE AND NONITERATIVE METHODS FOR THE SOLUTION OF THE NONLINEAR RICHARDS EQUATION

Several noniterative procedures for solving the nonlinear Richards equation are introduced and compared to the conventional Newton and Picard iteration methods. Noniterative strategies for the numerical solution of transient, nonlinear equations arise from explicit or linear time discretizations, or they can be obtained by linearizing an implicit differencing scheme. We present two first order accurate linearization methods, a second order accurate two-level “implicit factored” scheme, and a second order accurate three-level “Lees” method. The accuracy and computational efficiency of these four schemes and of the Newton and Picard methods are evaluated for a series of test problems simulating one-dimensional flow processes in unsaturated porous media. The results indicate that first order accurate schemes are inefficient compared to second order accurate methods; that second order accurate noniterative schemes can be quite competitive with the iterative Newton and Picard methods; and that the Newton scheme is no less efficient than the Picard method, and for strongly nonlinear problems can outperform the Picard scheme. The two second order accurate noniterative schemes appear to be attractive alternatives to the iterative methods, although there are concerns regarding the stability behavior of the three-level scheme which need to be resolved. We conclude that of the four noniterative strategies presented, the implicit factored scheme is the most promising, and we suggest improved formulations of the method.
spsurvey: Spatial Sampling Design and Analysis in R

spsurvey is an R package for design-based statistical inference, with a focus on spatial data. spsurvey provides the generalized random-tessellation stratified (GRTS) algorithm to select spatially balanced samples via the grts() function. The grts() function flexibly accommodates several sampling design features, including stratification, varying inclusion probabilities, legacy (or historical) sites, minimum distances between sites, and two options for replacement sites. spsurvey also provides a suite of data analysis options, including categorical variable analysis (cat_analysis()), continuous variable analysis cont_analysis()), relative risk analysis (relrisk_analysis()), attributable risk analysis (attrisk_analysis()), difference in risk analysis (diffrisk_analysis()), change analysis (change_analysis()), and trend analysis (trend_analysis()). In this manuscript, we first provide background for the GRTS algorithm and the analysis approaches and then show how to implement them in spsurvey. We find that the spatially balanced GRTS algorithm yields more precise parameter estimates than simple random sampling, which ignores spatial information.
Chiral symmetry breaking and pions in nonsupersymmetric gauge / gravity duals

We study gravity duals of large N nonsupersymmetric gauge theories with matter in the fundamental representation by introducing a D7-brane probe into deformed AdS backgrounds. In particular, we consider a D7-brane probe in both the AdS Schwarzschild black hole solution and in the background found by Constable and Myers, which involves a nonconstant dilaton and S5 radius. Both these backgrounds exhibit confinement of fundamental matter and a discrete glueball and meson spectrum. We numerically compute the Psi-bar Psi condensate and meson spectrum associated with these backgrounds. In the AdS–black-hole background, a quark-bilinear condensate develops only at a nonzero quark mass. We speculate on the existence of a third order phase transition at a critical quark mass where the D7 embedding undergoes a geometric transition. In the Constable-Myers background, we find a chiral symmetry breaking condensate as well as the associated Goldstone boson in the limit of small quark mass. The existence of the condensate ensures that the D7-brane never reaches the naked singularity at the origin of the deformed AdS space.