Near-field polarization conversion in planar chiral nanostructures

Enantiomeric-sensitive optical polarization conversion has been observed in the near-field above a planar chiral nanostructures consisting of an array of gammadions cut in a metal film. Formation of the far-field scattered light rotated with respect to the incident linear polarized light has been visualized

Sampling Distributions of Random Electromagnetic Fields in Mesoscopic or Dynamical Systems

We derive the sampling probability density function (pdf) of an ideal localized random electromagnetic field, its amplitude and intensity in an electromagnetic environment that is quasi-statically time-varying statistically homogeneous or static statistically inhomogeneous. The results allow for the estimation of field statistics and confidence intervals when a single spatial or temporal stochastic process produces randomization of the field. Results for both coherent and incoherent detection techniques are derived, for Cartesian, planar and full-vectorial fields. We show that the functional form of the sampling pdf depends on whether the random variable is dimensioned (e.g., the sampled electric field proper) or is expressed in dimensionless standardized or normalized form (e.g., the sampled electric field divided by its sampled standard deviation). For dimensioned quantities, the electric field, its amplitude and intensity exhibit different types of Bessel $K$ sampling pdfs, which differ significantly from the asymptotic Gauss normal and $\chi^{(2)}_{2p}$ ensemble pdfs when $\nu$ is relatively small. By contrast, for the corresponding standardized quantities, Student $t$, Fisher-Snedecor $F$ and root-$F$ sampling pdfs are obtained that exhibit heavier tails than comparable Bessel $K$ pdfs. Statistical uncertainties obtained from classical small-sample theory for dimensionless quantities are shown to be overestimated compared to dimensioned quantities. Differences in the sampling pdfs arising from de-normalization versus de-standardization are obtained.Comment: 12 pages, 15 figures, accepted for publication in Phys. Rev. E, minor typos correcte

The effect of structural changes on magnetic permeability of amorphous powder Ni80Co20

The structural changes of Ni80Co20 amorphous powder were tested during heating. The alloy was obtained by electrolysis from ammonia solution sulfate of cobalt and nickel on the titanium cathode. The differential scanning calorimetry (DSC) method was used to detect that the crystallization process of powder occurred in two stages with crystallization peaks temperatures of the first stage at 690 K and of the second stage at 790 K. The effect of structural relaxation and crystallization of powder on magnetic properties was predicted by measurement of the relative magnetic permeability change in isothermal and nonisothermal conditions. On the basis of the time change of relative magnetic permeability at a defined temperature in the temperature range of the first and second crystallization peak on the thermogram, the kinetics of crystallization was defined. It was predicted, that in the initial time interval, in the range of the first crystallization peak, the rate of crystallization is determined by the rate of nucleation of the amorphous part of the powder. However, in the second time interval, the crystallization rate is determined by the rate of diffusion. In the range of the second peak, in the beginning the rate of crystal growth is determined by activation energy of the atom pass from smaller to bigger crystal grain. In second time interval, the rate of crystal grain growth is determined by the diffusion rate of atoms to the location of integration into bigger crystal grains. For all processes which determine the rate of crystallization in temperature ranges of both crystallization peaks, the Arrhenius temperature dependence of rate for those processes is obtained. The relative magnetic permeability of crystallized powder at 873 K, is smaller for about 30 % than the relative magnetic permeability of fresh powder at room temperature. However, structurally relaxed powder at 573 K has an about 22 % larger magnetic permeability than the same fresh powder at room temperature

Conservation and entanglement of Hermite-Gaussian modes in parametric down-conversion

We show that the transfer of the angular spectrum of the pump beam to the two-photon state in spontaneous parametric down-conversion enables the generation of entangled Hermite-Gaussian modes. We derive an analytical expression for the two-photon state in terms of these modes and show that there are restrictions on both the parity and order of the down-converted Hermite-Gaussian fields. Using these results, we show that the two-photon state is indeed entangled in Hermite-Gaussian modes. We propose experimental methods of creating maximally-entangled Bell states and non-maximally entangled pure states of first order Hermite-Gaussian modes.Comment: 9 pages, 4 figures. Corrections made as per referee comments, references updated. Submitted PR

Nonstationary random acoustic and electromagnetic fields as wave diffusion processes

We investigate the effects of relatively rapid variations of the boundaries of an overmoded cavity on the stochastic properties of its interior acoustic or electromagnetic field. For quasi-static variations, this field can be represented as an ideal incoherent and statistically homogeneous isotropic random scalar or vector field, respectively. A physical model is constructed showing that the field dynamics can be characterized as a generalized diffusion process. The Langevin--It\^{o} and Fokker--Planck equations are derived and their associated statistics and distributions for the complex analytic field, its magnitude and energy density are computed. The energy diffusion parameter is found to be proportional to the square of the ratio of the standard deviation of the source field to the characteristic time constant of the dynamic process, but is independent of the initial energy density, to first order. The energy drift vanishes in the asymptotic limit. The time-energy probability distribution is in general not separable, as a result of nonstationarity. A general solution of the Fokker--Planck equation is obtained in integral form, together with explicit closed-form solutions for several asymptotic cases. The findings extend known results on statistics and distributions of quasi-stationary ideal random fields (pure diffusions), which are retrieved as special cases.Comment: 54 pages, 8 figures, to appear in J. Phys. A: Math. Theo

Validation of new injury severity score in severe trauma from autochthonous medical system

Universitatea de Stat de Medicină și Farmacie „Nicolae Testemițanu”, Chișinău, Republica Moldova, Al XIII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” și al III-lea Congres al Societății de Endoscopie, Chirurgie miniminvazivă și Ultrasonografie ”V.M.Guțu” din Republica MoldovaIntroducere: Determinarea scorului bilanțului lezional este decisivă pentru tactica și rezultatele tratamentului, mai ales pentru pacienții cu traumatisme severe (TS). Actualmente, după datele din literatură, nu există un consens în principalele registre de traumă pentru estimarea probabilității de deces. Scopul cercetării a fost validarea New Injury Severity Score (NISS) pentru pacienții cu TS din sistemul medical autohton. Material și metode: Studiul retrospectiv a inclus 467 de pacienți cu TS (NISS>15) internați în perioada acută a traumei în secția Reanimare (SR) a Institutului de Medicină Urgentă (Chișinău). Analiza de regresie a estimat puterea predictivă a NISS pentru TS din SR, ajustată la vârsta și gender. Rezultate obținute: Coeficientul de determinare a constituit 51.1%, NISS având 42.4% din dispersia variabilei “deces”. Testul HosmerLemeshow a demonstrat fidelitаteа сresсută а modelului (χ2(df=8)=4.462, p=0.813), sensibilitatea și specificitatea având peste 80%. În conformitatea cu rezultatele analizei multivariate, probabilitatea de deces (p) poate fi estimată după ecuația p=1/1+e^(9.171 - 0.58*Vârsta – 0.142*NISS), unde e (exponenta)= 2.71828. Concluzii: Scorul NISS a fost validat pentru contingentul respectiv de pacienț cu TS. În perspectivă se pot preconiza studii prospective de validare a NISS, precum și evaluarea comparativă a diferitor scoruri traumatice în cadrul sistemului medical autohton.Introduction: Trauma severity determination is critical for treatment strategy and outcomes, especially for severe injured patients (ST). Currently, according to literature data, there is no consensus among the main trauma registers for estimating the probability of death. The purpose of the research was to validate the New Injury Severity Score (NISS) for ST patients from Moldova’s medical system. Material and methods: The retrospective study included 467 ST patients (NISS> 15) admitted in acute period to Reanimatology department (RD) of Institute of Emergency Medicine (Chişinău). The regression analysis estimated NISS predictive power for ST in RD, adjusted for age and gender. Results: The Nagelkerke R Square was 51.1%, NISS having 42.4% of the "death" variable dispersion. The Hosmer-Lemeshow test demonstrated the high fidelity of the of the model (χ2 (df = 8) = 4.462, p = 0.813), the sensitivity and specificity being over 80%. According to the multivariate analysis, the probability of death (p) can be estimated by the following equation: p = 1/1 + e ^ (9.171 - 0.58 * Age - 0.142 * NISS), where e (exponenta) = 2.71828. Conclusions: The NISS score has been validated for the patient's TS from RD. Looking ahead, prospective NISS validation studies can be expected, as well as comparative evaluation of different traumatic scores in the Moldova’s medical system

Entanglement of photons

It is argued that the title of this paper represents a misconception. Contrary to widespread beliefs it is electromagnetic field modes that are ``systems'' and can be entangled, not photons. The amount of entanglement in a given state is shown to depend on redefinitions of the modes; we calculate the minimum and maximum over all such redefinitions for several examples.Comment: 5 pages ReVTe

Entangled Bessel beams

Orbital angular momentum (OAM) entanglement is investigated in the Bessel-Gauss (BG) basis. Having a readily adjustable radial scale, BG modes provide a more favourable basis for OAM entanglement over Laguerre-Gaussian (LG) modes. The OAM bandwidth in terms of BG modes can be increased by selection of particular radial modes and leads to a flattening of the spectrum. The flattening of the spectrum allows for higher entanglement. We demonstrate increased entanglement in terms of BG modes by performing a Bell-type experiment and violating the appropriate Clauser Horne Shimony Holt (CHSH) inequality. In addition, we reconstruct the quantum state of BG modes entangled in high-dimensions.Comment: 8 pages, 4 figure