Model-independent quantum phases classifier.

Machine learning has transformed science and technology. In this article, we present a model-independent classifier that uses the k-Nearest Neighbors algorithm to classify phases of a model for which it has never been trained. This is done by studying three different spin-1 chains with some common phases: the XXZ chains with uniaxial single-ion-type anisotropy, the bond alternating XXZ chains, and the bilinear biquadratic chain. We show that the algorithm trained with two of these models can, with high probability, determine phases common to the third one. This is the first step towards a universal classifier, where an algorithm can recognize an arbitrary phase without knowing the Hamiltonian, since it knows only partial information about the quantum state.

Transmittance and optical constants of Ca films in the 4-1000 eV spectral range.

The low expected absorption of Ca in the extreme ultraviolet (EUV) makes it an attractive material for multilayers and filters because most materials in nature strongly absorb the EUV. Few optical constant data had been reported for Ca. In this research, Ca films of various thicknesses were deposited on grid-supported C films and their transmittance measured in situ from the visible to the soft x-rays. The measurement range contains M2,3 and L2,3 absorption edges. Transmittance measurements were used to obtain the Ca extinction coefficient k. A minimum k of 0.017 was obtained at ∼23 eV, which makes Ca a promising low-absorption material for EUV coatings. A second spectral range of interest for its low absorption is below the Ca L3 edge at ∼343 eV. Measured k data and extrapolations were used to calculate the refractive index n using Kramers-Krönig relations. This is the first self-consistent data set on Ca covering a wide spectral range including the EUV.

Transmittance and optical constants of erbium films in the 3.25-1580 eV spectral range.

The optical constants of erbium (Er) films were obtained in the 3.25-1580 eV range from transmittance measurements performed at room temperature. Thin films of Er were deposited by evaporation in ultra high vacuum conditions and their transmittance was measured in situ. Substrates consisted of a thin C film supported on a grid. Transmittance measurements were used to obtain the extinction coefficient k of the Er films. The refractive index n of Er was calculated using the Kramers-Krönig analysis. k data were extrapolated both on the high- and low-energy parts of the spectrum by using experimental data and calculated k values available in the literature. Er, similar to other lanthanides, has a low-absorption band below the O(2,3) edge onset; the smallest absorption was measured at ~22.5 eV. Therefore, Er is a promising material for filters and multilayer coatings in the energy range below the O(2,3) edge, in which materials typically have an absorption stronger than at other energies. Good consistency of the data resulted from the application of f and inertial sum rules.

Optical constants of Yb films in the 23-1700 eV range.

The optical constants of Yb films have been determined in the 23-1700 eV spectral range from transmittance measurements performed in situ on Yb films deposited by evaporation in ultrahigh vacuum conditions. Yb films were deposited over grids coated with a thin carbon film. Transmittance measurements were used to obtain the extinction coefficient of Yb films at each individual photon energy investigated. The energy range investigated encompasses Yb edges from M(4,5) to O(2,3). The current results, along with data in the literature, show that Yb has an interesting low-absorption band in the approximately 12-24 eV range, which may be useful for the development of transmittance filters and multilayer coatings. The current data along with literature data and extrapolations were used to obtain n, the real part of the complex refractive index, using a Kramers-Krönig analysis. The application of the sum rules showed a good consistency of the results.

Determination of optical constants of scandium films in the 20-1000 eV range.

The transmittance of thin films of Sc deposited by evaporation in ultrahigh vacuum conditions has been investigated in the 20-1000 eV spectral range. Transmittance measurements were performed in situ on Sc layers that were deposited over grids coated with a C support film. Transmittance measurements were used to obtain the extinction coefficient of Sc films at each individual photon energy investigated. These data, along with the data available in the literature for the rest of the spectrum, were used to obtain the refractive index of Sc by means of the Kramers-Krönig analysis. Sum-rule tests indicated an acceptable consistency of the data.

Melting-induced enhancement of the second-harmonic generation from metal nanoparticles.

We report on the generation of second-harmonic signals by irradiating monolayers of high purity Ga nanoparticles, embedded in a SiOx matrix, with femtosecond laser pulses at 800 nm. A remarkable melting-induced enhancement of the second-harmonic generation is observed in correspondence of the phase transition. In addition, the hysteresis cycle of nonlinear transmittance is shown to be amplified a factor of 80-100 with respect to the linear response and interpreted in the framework of a nonlinear effective-medium model.

[Spontaneous grade I bundle of His block. Clinical, electrocardiographic and electrophysiological studies in 37 patients]. / Il blocco intrahisiano di I grado spontaneo. Osservazioni cliniche, elettrocardiografiche ed elettrofisiologiche in 37 pazienti.

The clinical, ECG and electrophysiological data of 37 patients (28 males and 9 females) with spontaneous intra-hisian block are reported. Of these patients, 11 had hypertensive heart disease and 5 had ischemic heart disease with previous myocardial infarction; in 21 patients, clinical signs of heart disease were not evident. In 18 patients, a single or recurrent episode of syncope had occurred. One patient had junctional rhythm and 36 sinus rhythm; among these, 12 patients presented PR greater than 200 msec (7 with a narrow and 5 with a wide QRS); 12 patients had a single or bilateral bundle branch block; 12 had a normal ECG. The electrophysiological study showed a split H-H1 in 22 patients, a wide His deflection (H greater than 25 msec) in 4 and HV greater than 65 msec with narrow QRS in 11. In 17 patients a more or less marked sinoatrial node and/or atrioventricular node dysfunction was present. Atrial pacing, performed in all, induced 2nd degree Mobitz 2 intra-hisian block in 9 patients. Ajmaline was used in 16 patients but induced a complete intra-hisian block in only one. In 28 patients a preventive pacemaker was implanted after electrophysiological study. During the follow-up (mean 25 months/pt.), 38% of the patients developed complete atrioventricular block. No recurrence of syncope occurred in the paced patients. Comparison of patients who developed atrioventricular block and those who maintained normal atrioventricular conduction did not show differences as far as heart disease, previous syncope, ECG pattern and results were concerned.(ABSTRACT TRUNCATED AT 250 WORDS)

Grazing incidence toroidal mirror pairs in imaging and spectroscopic applications.

The optical performance of pairs of toroidal mirrors in grazing incidence has been studied analytically and numerically. Two types of toroidal surface are possible: football and bicycle tire. In grazing incidence and for configurations that compensate up to second-order aberrations, there are significant differences in performance between the two types. For football-type tori the best configuration appears to be Z-shaped with tangential and sagittal foci at the middle point between the mirrors. For bicycle tire-type tori the best configuration is U-shaped with the tangential focus at the middle point and the sagittal at infinity.

[R wave variations during the bicycle exercise test]. / Variazioni dell'onda R in corso di prova da sforzo al cicloergometro.

R-wave changes have been measured in 90 normal subjects during exercise testing on the bicycle. We have found a 22,2% R-wave mean decrease in all the subjects independently from their age. This results, in our opinion, may be due to the heart volume decrease during dynamic exercise in normal subjects. In according to the Brody effect, heart volume reduction decrease radially orientated cardiac vectors and therefore QRS amplitude is reduced.

[Effect of isometric force (handgrip) on R wave amplitude]. / Effetto dello sforzo isometrico (handgrip) sull'ampiezza dell'onda R.

We have measured R-wave amplitude during isometric stress-handgrip test in 30 normal subjects, without finding any significative variation. We believe, in according to our angiographic and echocardiographic experience, that such a behaviour is due to the absence of heart volume modification during handgrip test.

Grazing-incidence high-resolution stigmatic spectrograph with two optical elements.

Using two optical toroidal elements, a mirror and a grating, both working at grazing incidence, a spectrometer can be built that is stigmatic in the XUV region at one wavelength. Good compensation of the aberrations is achieved when the intermediate sagittal image is nearly at infinity. By varying the angle of incidence on the grating with simple movements, a given couple of optical elements could cover stigmatically a rather extended spectral range. If coupled with bidimensional array detectors, such a spectrograph could find applications in planned solar XUV telescopes.

[Rheographic evaluation of peripheral blood flow during isometric exercise]. / Valutazione reografica del flusso sanguigno periferico in corso di esercizio isometrico.

A rheographic evaluation of peripheral blood flow during isometric contraction (handgrip) has been done in 25 attendants of the Air Force Medical Service (mean age :20 years). The velocity of sphygmic wave, the sphygmic amplitude and, the peak time, heart rate and blood pressure have been measured at rest and during handgrip. The velocity of sphygmic wave does not change in all the subjects; the sphygmic amplitude is decreased of 10% (p less than .001), the peak time is decreased of 9% (p less than .001). Because sphygmic amplitude and peak time are directly proportional to flow volume, and their reduction significantly express a decrease of flow volume. The authors believe that the blood flow reduction is induced by the excitation of sympathetic peripheral alpha-receptors, not more balanced from sympathetic cholinergic vasodilator fibers. The actual result is an increase of the peripheral vascular resistances.

Grazing incidence spectrograph-monochromator with a focusing toroidal mirror.

The use of a toroidal mirror in front of a spherical grating spectrograph working at grazing incidence provides a system that is stigmatic in one dimension in the extreme ultraviolet (XUV) region and allows spectroscopy with space resolution. The system is optimized for spectral and spatial resolution and for efficiency. By using three toroidal mirrors mounted on a suitable turret and a new model of grazing incidence spectrometer, the system is capable of covering the whole XUV region. All the necessary movements are internal to the system and do not involve the source. Two examples are treated, one for a diagnostic study of laser-produced pellets and another for observation of large plasma machines.

[Effects of isometric exercise on the pulmonary circulation in aortic patients]. / Effetti dell'espercizio isometrico sul circolo polmonare negli aortici.

The hemodynamic changes of the pulmonary vascular system in patients with aortic stenosis, has been evaluated during isometric exercise (handgrip). Heart rate, left ventricular sistolic pressure and pulmonary artery sistolic pressure, increase significantly while pulmonary vascular resistences are uneffected. In conclusion, the pulmonary response to handgrip olso in patients with aortic stenosis shows the same.

Grazing incidence spectrograph-monochromator for xuv spectroscopy in the 5-900 A region.

A combination grazing incidence spectrograph for photographic recording and scanning monochromator has been realized. The instrument is of a modular concept and all the internal components like the grating, the plateholder, and the scanning exit slit are easily removable. The radius of curvature of the Rowland cylinder can also be easily changed. The entrance beam is always kept fixed in position and direction, allowing the instrument to be permanently aligned with fixed light sources. The vacuum case is mechanically independent from the optical components.

[Effect of isometric exercise on the lesser circulation in a group of patients with mitral stenosis]. / Effetti dello sforzo isometrico sul piccolo circolo in un gruppo di pazienti affetti da stenosi mitralica.

The hemodynamic changes of the pulmonary vascular system in patients with mitral stenosis, has been evaluated during isometric exercise (handgrip). Heart rate, pulmonary artery sistolic, dyastolic, mean and "wedged" pressure, end-dyastolic pulmonary vascular and trans-mitralic gradient, total pulmonary resistences increase significantly. Cardiac output and pulmonary vascular bed are probably related to the tachycardia induced by the handgrip, and to the conseguent shortening of the dyastolic left ventricular filling time.