From Light Nuclei to Nuclear Matter. The Role of Relativity?

The success of non-relativistic quantum dynamics in accounting for the binding energies and spectra of light nuclei with masses up to A=10 raises the question whether the same dynamics applied to infinite nuclear matter agrees with the empirical saturation properties of large nuclei.The simple unambiguous relation between few-nucleon and many-nucleon Hamiltonians is directly related to the Galilean covariance of nonrelativistic dynamics. Relations between the irreducible unitary representations of the Galilei and Poincare groups indicate thatthe ``nonrelativistic'' nuclear Hamiltonians may provide sufficiently accurate approximations to Poincare invariant mass operators. In relativistic nuclear dynamics based on suitable Lagrangeans the intrinsic nucleon parity is an explicit, dynamically relevant, degree of freedom and the emphasis is on properties of nuclear matter. The success of this approach suggests the question how it might account for the spectral properties of light nuclei.Comment: conference proceedings "The 11th International Conference on Recent Progress in Many-Body Theories" to be published by World Scientifi

Superconducting On-chip Fourier Transform Spectrometer

The kinetic inductance effect is strongly nonlinear with applied current in NbTiN, TiN and NbN thin films. This can be utilized to realize novel devices. We present results from transmission lines made with these materials, where DC (current) control is used to modulate the phase velocity thereby enabling on-chip spectrometers. Utility of such compact spectrometers is discussed, along with their natural connection with parametric amplifiers

Total scattering descriptions of local and cooperative distortions in the oxide spinel (Mg,Cu)Cr2O4 with dilute Jahn-Teller ions

The normal spinel oxide MgCr2O4 is cubic at room temperature while the normal spinel CuCr2O4 is tetragonal as a consequence of the Jahn-Teller nature of Cu2+ on the tetrahedral sites. Despite different end-member structures, complete solid solutions of Mg_{1-x}Cu_xCr2O4 can be prepared that display a first-order structural transition with composition x = 0.43 at room temperature. Reverse Monte Carlo analysis of total neutron scattering on data acquired between 300 K and 15 K on samples with x = 0.10, 0.20, and 0.43 provides unbiased local and average structure descriptions of the samples, including an understanding of the transition from local Jahn-Teller distortions in the cubic phase to cooperative distortions that result in a tetragonal structure. Distributions of continuous symmetry measures help to understand and distinguish distorted and undistorted coordination around the tetrahedral site in the solid solutions. Magnetic exchange bias is observed in field-cooled hysteresis loops of samples with dilute Cu2+ concentration and in samples with tetragonal--cubic phase coexistence around 300 K.Comment: 10 pages, 14 figure

Critical Temperature tuning of Ti/TiN multilayer films suitable for low temperature detectors

We present our current progress on the design and test of Ti/TiN Multilayer for use in Kinetic Inductance Detectors (KIDs). Sensors based on sub-stoichiometric TiN film are commonly used in several applications. However, it is difficult to control the targeted critical temperature $T_C$, to maintain precise control of the nitrogen incorporation process and to obtain a production uniformity. To avoid these problems we investigated multilayer Ti/TiN films that show a high uniformity coupled with high quality factor, kinetic inductance and inertness of TiN. These features are ideal to realize superconductive microresonator detectors for astronomical instruments application but also for the field of neutrino physics. Using pure Ti and stoichiometric TiN, we developed and tested different multilayer configuration, in term of number of Ti/TiN layers and in term of different interlayer thicknesses. The target was to reach a critical temperature $T_C$ around $(1\div 1.5)$ K in order to have a low energy gap and slower recombination time (i.e. low generation-recombination noise). The results prove that the superconductive transition can be tuned in the $(0.5\div 4.6)$ K temperature range properly choosing the Ti thickness in the $(0\div 15)$ nm range, and the TiN thickness in the $(5\div 100)$ nm rang

Universality of residence-time distributions in non-adiabatic stochastic resonance

We present mathematically rigorous expressions for the residence-time and first-passage-time distributions of a periodically forced Brownian particle in a bistable potential. For a broad range of forcing frequencies and amplitudes, the distributions are close to periodically modulated exponential ones. Remarkably, the periodic modulations are governed by universal functions, depending on a single parameter related to the forcing period. The behaviour of the distributions and their moments is analysed, in particular in the low- and high-frequency limits.Comment: 8 pages, 1 figure New version includes distinction between first-passage-time and residence-time distribution

Phosphonopeptides Revisited, in an Era of Increasing Antimicrobial Resistance

Given the increase in resistance to antibacterial agents, there is an urgent need for the development of new agents with novel modes of action. As an interim solution, it is also prudent to reinvestigate old or abandoned antibacterial compounds to assess their efficacy in the context of widespread resistance to conventional agents. In the 1970s, much work was performed on the development of peptide mimetics, exemplified by the phosphonopeptide, alafosfalin. We investigated the activity of alafosfalin, di-alanyl fosfalin and β-chloro-L-alanyl-β-chloro-L-alanine against 297 bacterial isolates, including carbapenemase-producing Enterobacterales (CPE) (n = 128), methicillin-resistant Staphylococcus aureus (MRSA) (n = 37) and glycopeptide-resistant enterococci (GRE) (n = 43). The interaction of alafosfalin with meropenem was also examined against 20 isolates of CPE. The MIC50 and MIC90 of alafosfalin for CPE were 1 mg/L and 4 mg/L, respectively and alafosfalin acted synergistically when combined with meropenem against 16 of 20 isolates of CPE. Di-alanyl fosfalin showed potent activity against glycopeptide-resistant isolates of Enterococcus faecalis (MIC90; 0.5 mg/L) and Enterococcus faecium (MIC90; 2 mg/L). Alafosfalin was only moderately active against MRSA (MIC90; 8 mg/L), whereas β-chloro-L-alanyl-β-chloro-L-alanine was slightly more active (MIC90; 4 mg/L). This study shows that phosphonopeptides, including alafosfalin, may have a therapeutic role to play in an era of increasing antibacterial resistance

Synthesis of new chiral organosulfur donors with hydrogen bonding functionality and their first charge transfer salts

The syntheses of a range of enantiopure organosulfur donors with hydrogen bonding groups are described including TTF related materials with two, four, six and eight hydroxyl groups and multiple stereogenic centres and a pair of chiral N-substituted BEDT-TTF acetamides. Three charge transfer salts of enantiopure poly-hydroxy-substituted donors are reported, including a 4:1 salt with the meso stereoisomer of the dinuclear [Fe2(oxalate)5 ]4- anion in which both cation and anion have chiral components linked together by hydrogen bonding, and a semiconducting salt with triiodide

The brightest pure-H ultracool white dwarf

We report the identification of LSR J0745+2627 in the United Kingdom InfraRed Telescope Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) as a cool white dwarf with kinematics and age compatible with the thick-disk/halo population. LSR J0745+2627 has a high proper motion (890 mas/yr) and a high reduced proper motion value in the J band (H_J=21.87). We show how the infrared-reduced proper motion diagram is useful for selecting a sample of cool white dwarfs with low contamination. LSR J0745+2627 is also detected in the Sloan Digital Sky Survey (SDSS) and the Wide-field Infrared Survey Explorer (WISE). We have spectroscopically confirmed this object as a cool white dwarf using X-Shooter on the Very Large Telescope. A detailed analysis of its spectral energy distribution reveals that its atmosphere is compatible with a pure-H composition model with an effective temperature of 3880+-90 K. This object is the brightest pure-H ultracool white dwarf (Teff<4000 K) ever identified. We have constrained the distance (24-45 pc), space velocities and age considering different surface gravities. The results obtained suggest that LSR J0745+2627 belongs to the thick-disk/halo population and is also one of the closest ultracool white dwarfs.Comment: 5 pages, 7 figures, accepted for publication in A&A Letter

Superscaling in inclusive electron-nucleus scattering

We investigate the degree to which the scaling functions $F(\psi')$ derived from cross sections for inclusive electron-nucleus quasi-elastic scattering define the same function for different nuclei. In the region where the scaling variable $\psi'< 0$, we find that this superscaling is experimentally realized to a high degree.Comment: Corrected previously mislabeled figures and cross references; 9 pages, 4 color figures, using BoxedEPS and REVTeX; email correspondence to [email protected]

The Arecibo L-band Feed Array Zone of Avoidance Survey I: Precursor Observations through the Inner and Outer Galaxy

The Arecibo L-band Feed Array (ALFA) is being used to conduct a low-Galactic latitude survey, to map the distribution of galaxies and large-scale structures behind the Milky Way through detection of galaxies' neutral hydrogen (HI) 21-cm emission. This Zone of Avoidance (ZOA) survey finds new HI galaxies which lie hidden behind the Milky Way, and also provides redshifts for partially-obscured galaxies known at other wavelengths. Before the commencement of the full survey, two low-latitude precursor regions were observed, totalling 138 square degrees, with 72 HI galaxies detected. Detections through the inner Galaxy generally have no cataloged counterparts in any other waveband, due to the heavy extinction and stellar confusion. Detections through the outer Galaxy are more likely to have 2MASS counterparts. We present the results of these precursor observations, including a catalog of the detected galaxies, with their HI parameters. The survey sensitivity is well described by a flux- and linewidth-dependent signal-to-noise ratio of 6.5. ALFA ZOA galaxies which also have HI measurements in the literature show good agreement between our measurements and previous work. The inner Galaxy precursor region was chosen to overlap the HI Parkes Zone of Avoidance Survey so ALFA performance could be quickly assessed. The outer Galaxy precursor region lies north of the Parkes sky. Low-latitude large-scale structure in this region is revealed, including an overdensity of galaxies near l = 183 deg and between 5000 - 6000 km/s in the ZOA. The full ALFA ZOA survey will be conducted in two phases: a shallow survey using the observing techniques of the precursor observations, and also a deep phase with much longer integration time, with thousands of galaxies predicted for the final catalog.Comment: 26 pages, 7 figures, 2 tables, Astronomical Journal accepte