New interpretation of Penning spectra from alkali-metal atoms chemisorbed on metal surfaces

Penning deexcitation spectra of alkali atoms adsorbed on metals show an intense peak at the Fermi level for coverages around the work-function minimum. This strong electron emission is assigned to the decay of a core-excited negative He-ion created by resonance transition of a substrate electron into the affinity level of the metastable rare-gas atom. The formation of this species also easily provides an explanation for the observed He* singlet-triplet conversion

Instanton picture of the spin tunneling in the Lipkin model

A consistent theory of the ground state energy and its splitting due to the process of tunneling for the Lipkin model is presented. For the functional integral in terms of the spin coherent states for the partition function of the model we accurately calculate the trivial and the instanton saddle point contributions. We show that such calculation has to be perfomed very accurately taking into account the discrete nature of the functional integral. Such accurate consideration leads to finite corrections to a naive continous consideration. We present comparison with numerical calculation of the ground state energy and the tunneling splitting and with the results obtained by the quasiclassical method and get excellent agreement.Comment: REVTEX, 32 pages, 3 figure

Oscillatory Tunnel Splittings in Spin Systems: A Discrete Wentzel-Kramers-Brillouin Approach

Certain spin Hamiltonians that give rise to tunnel splittings that are viewed in terms of interfering instanton trajectories, are restudied using a discrete WKB method, that is more elementary, and also yields wavefunctions and preexponential factors for the splittings. A novel turning point inside the classically forbidden region is analysed, and a general formula is obtained for the splittings. The result is appled to the \Fe8 system. A previous result for the oscillation of the ground state splitting with external magnetic field is extended to higher levels.Comment: RevTex, one ps figur

Aan de wieg van het waterschap : inventarisatie van dijken, kaden en watergangen in het Gelders rivierengebied : ontwerphandreikingen voor wateropgaven

De studie geeft een inventarisatie van ontginningspatronen van het rivierengebied. Deze patronen reflecteren de geschiedenis van de bewoners én de geschiedenis van het Waterschap. Dijken, kaden en weteringen vormden in tijden van weleer de begrenzing van de dorpspolders. De dorpspolders zijn de voorlopers van de waterschappen. Deze studie van een landschapsarchitect, landschapshistoricus en bodemkundige vertelt een verhaal. Een verhaal over de geschiedenis hoe dit gebied bewoonbaar en bewerkbaar wer

The photon‐induced reactions of chemisorbed CH₃Br on Pt{111}

The photochemistry of chemisorbed CH3Br on Pt{111} has been investigated using high resolution electron energy loss spectroscopy (HREELS) and thermal desorption. The primary photon‐induced reaction involves the cleavage of the C–Br bond, giving rise to chemisorbed CH3 and Br, both of which can be identified in HREELS. From the angular dependence of the loss peaks, the symmetry of the CH3 surface complex is shown to be C3v. HBr can also be identified in subsequent thermal desorption. Experiments performed directly with HBr on Pt{111} indicate that molecular HBr adsorbs dissociatively on this surface. This result, in combination with observations of the C–H vibrational mode as a function of temperature, shows that the production of HBr arises from a secondary surface reaction between Br and CHx fragments. Based on the wavelength dependence of the fragmentation cross section and the photoemission spectrum of adsorbed CH3Br the primary photon‐induced reaction to a charge transfer excitation is ascribed

Elementary School Social Emotional Learning Status and Attendance, Discipline, and Achievement in the United States: A National Analysis

Ascertained in this investigation was the effect of social emotional learning training on student attendance, discipline problems and actions, students’ thoughts on the importance of academic achievement, and urbanicity in public elementary schools for the 2015-2016 and 2017-2018 school years. We analyzed data from two School Surveys on Crime and Safety conducted across the United States. Across the two years, social emotional learning training was determined to be unrelated to public elementary schools’ location (i.e., urban, suburban, rural), student attendance or discipline problems and actions. The presence of social emotional learning training, however, was determined to be related to the importance of academic achievement. Implications for policy and for practice, along with recommendations for future research, were made

Large Deviation Property of Free Energy in p-Body Sherrington-Kirkpatrick Model

Cumulant generating function phi(n) and rate function Sigma(f) of the free energy is evaluated in p-body Sherrington-Kirkpatrick model by using the replica method with the replica number n finite. From a perturbational argument, we show that the cumulant generating function is constant in the vicinity of n = 0. On the other hand, with the help of two analytic properties of phi(n), the behavior of phi(n) is derived again. However this is also shown to be broken at a finite value of n, which gives a characteristic value in the rate function near the thermodynamic value of the free energy. Through the continuation of phi(n) as a function of n, we find out a way to derive the 1RSB solution at least in this model, which is to fix the RS solution to be a monotone increasing function.Comment: 7 pages, 5 figures. accepted for publication in J.Phs.Soc.Jp

Secure exchange of information by synchronization of neural networks

A connection between the theory of neural networks and cryptography is presented. A new phenomenon, namely synchronization of neural networks is leading to a new method of exchange of secret messages. Numerical simulations show that two artificial networks being trained by Hebbian learning rule on their mutual outputs develop an antiparallel state of their synaptic weights. The synchronized weights are used to construct an ephemeral key exchange protocol for a secure transmission of secret data. It is shown that an opponent who knows the protocol and all details of any transmission of the data has no chance to decrypt the secret message, since tracking the weights is a hard problem compared to synchronization. The complexity of the generation of the secure channel is linear with the size of the network.Comment: 11 pages, 5 figure

Xenon combined with therapeutic hypothermia is not neuroprotective after severe hypoxia-ischemia in neonatal rats

Therapeutic hypothermia (TH) is standard treatment following perinatal asphyxia in newborn infants. Experimentally, TH is neuroprotective after moderate hypoxia-ischemia (HI) in seven-day-old (P7) rats. However, TH is not neuroprotective after severe HI. After a moderate HI insult in newborn brain injury models, the anesthetic gas xenon (Xe) doubles TH neuroprotection. The aim of this study was to examine whether combining Xe and TH is neuroprotective as applied in a P7 rat model of severe HI.120 P7 rat pups underwent a severe HI insult; unilateral carotid artery ligation followed by hypoxia (8% O2 for 150min at experimental normothermia (NT-37: Trectal 37°C). Surviving pups were randomised to immediate NT-37 for 5h (n = 36), immediate TH-32: Trectal 32°C for 5h (n = 25) or immediate TH-32 plus 50% inhaled Xe for 5h (n = 24). Pups were sacrificed after one week of survival. Relative area loss of the ligated hemisphere was measured, and neurons in the subventricular zone of this injured hemisphere were counted, to quantify brain damage.Following the HI insult, median (interquartile range, IQR) hemispheric brain area loss was similar in all groups: 63.5% (55.5-75.0) for NT-37 group, 65.0% (57.0-65.0) for TH-32 group, and 66.5% (59.0-72.0) for TH-32+Xe50% group (not significant). Correspondingly, there was no difference in neuronal cell count (NeuN marker) in the subventricular zone across the three treatment groups.Immediate therapeutic hypothermia with or without additional 50% inhaled Xe, does not provide neuroprotection one week after severe HI brain injury in the P7 neonatal rat. This model aims to mimic the clinical situation in severely asphyxiated neonates and treatment these newborns remains an ongoing challenge