Nucleic acid vibrational circular dichroism, absorption, and linear dichroism spectra. I. A DeVoe theory approach

Infrared (IR) vibrational circular dichroism (VCD), absorption, and linear dichroism (LD) spectra of four homopolyribonucleotides, poly(rA), poly(rG), poly(rC), and poly(rU), have been calculated, in the 1750–1550 cm-1 spectral region, using the DeVoe polarizability theory. A newly derived algorithm, which approximates the Hilbert transform of imaginaries to reals, was used in the calculations to obtain real parts of oscillator polarizabilities associated with each normal mode. The calculated spectra of the polynucleotides were compared with previously measured solution spectra. The good agreement between calculated and measured polynucleotide spectra indicates, for the first time, that the DeVoe theory is a useful means of calculating the VCD and IR absorption spectra of polynucleotides. For the first time, calculated DeVoe theory VCD and IR absorption spectra of oriented polynucleotides are presented. The calculated VCD spectra for the oriented polynucleotides are used to predict the spectra for such measurements made in the future. The calculated IR spectra for the oriented polynucleotides are useful in interpreting the linear dichroism of the polynucleotides

Position and energy-resolved particle detection using phonon-mediated microwave kinetic inductance detectors

We demonstrate position and energy-resolved phonon-mediated detection of particle interactions in a silicon substrate instrumented with an array of microwave kinetic inductance detectors (MKIDs). The relative magnitude and delay of the signal received in each sensor allow the location of the interaction to be determined with ≲ 1mm resolution at 30 keV. Using this position information, variations in the detector response with position can be removed, and an energy resolution of σ_E = 0.55 keV at 30 keV was measured. Since MKIDs can be fabricated from a single deposited film and are naturally multiplexed in the frequency domain, this technology can be extended to provide highly pixelized athermal phonon sensors for ∼1 kg scale detector elements. Such high-resolution, massive particle detectors would be applicable to rare-event searches such as the direct detection of dark matter, neutrinoless double-beta decay, or coherent neutrino-nucleus scattering

Neutralino dark matter stars can not exist

Motivated by the recent "Cosmos Project" observation of dark-matter concentrations with no ordinary matter in the same place, we study the question of the existence of compact objects made of pure dark matter. We assume that the dark matter is neutralino, and compare its elastic and annihilation cross sections. We find that the two cross sections are of the same order of magnitude. This result has a straightforward and important consequence that neutralinos comprising a compact object can not achieve thermal equilibrium. To substantiate our arguments, by solving Oppenheimer-Volkoff equation we constructed a model of the star made of pure neutralinos. We explicitly showed that the condition for the thermal equilibrium supported by the Fermi pressure is never fulfilled inside the star. This neutralino state can not be described by the Fermi-Dirac distribution. Thus, a stable neutralino star, which is supported by the Fermi pressure, can not exist. We also estimated that a stable star can not contain more than a few percents of neutralinos, most of the mass must be in the form of the standard model particles.Comment: published in JHE

Atomic Dark Matter

We propose that dark matter is dominantly comprised of atomic bound states. We build a simple model and map the parameter space that results in the early universe formation of hydrogen-like dark atoms. We find that atomic dark matter has interesting implications for cosmology as well as direct detection: Protohalo formation can be suppressed below $M_{proto} \sim 10^3 - 10^6 M_{\odot}$ for weak scale dark matter due to Ion-Radiation interactions in the dark sector. Moreover, weak-scale dark atoms can accommodate hyperfine splittings of order 100 \kev, consistent with the inelastic dark matter interpretation of the DAMA data while naturally evading direct detection bounds.Comment: 17 pages, 3 figure

Cranked Relativistic Hartree-Bogoliubov Theory: Superdeformed Bands in the A∼190A\sim 190 Region

Cranked Relativistic Hartree-Bogoliubov (CRHB) theory is presented as an extension of Relativistic Mean Field theory with pairing correlations to the rotating frame. Pairing correlations are taken into account by a finite range two-body force of Gogny type and approximate particle number projection is performed by Lipkin-Nogami method. This theory is applied to the description of yrast superdeformed rotational bands observed in even-even nuclei of the $A\sim 190$ mass region. Using the well established parameter sets NL1 for the Lagrangian and D1S for the pairing force one obtains a very successful description of data such as kinematic ($J^{(1)}$) and dynamic ($J^{(2)}$) moments of inertia without any adjustment of new parameters. Within the present experimental accuracy the calculated transition quadrupole moments $Q_t$ agree reasonably well with the observed data.Comment: 6 pages including 4 PostScript figures, uses RevTex, revised version, Phys.Rev. C, Rapid Communications, in pres

Effects of in vitro purging with 4-hydroperoxycyclophosphamide on the hematopoietic and microenvironmental elements of human bone marrow

We describe the effects of 4-hydroperoxycyclophosphamide (4-HC) on the hematopoietic and stromal elements of human bone marrow. Marrow cells were exposed to 4-HC and then assayed for mixed (CFU-Mix), erythroid (BFU-E), granulomonocytic (CFU-GM), and marrow fibroblast (CFU-F) colony-forming cells and studied in the long-term marrow culture (LTMC) system. The inhibition of colony formation by 4-HC was dose and cell-concentration dependent. The cell most sensitive to 4-HC was CFU-Mix (ID50 31 mumol/L) followed by BFU-E (ID50 41 mumol/L), CFU-GM (ID50 89 mumol/L), and CFU-F (ID50 235 mumol/L). In LTMC, a dose-related inhibition of CFU-GM production was noted. Marrows treated with 300 mumol/L 4-HC were completely depleted of CFU-GM but were able to generate these progenitors in LTMC. Marrow stromal progenitors giving rise to stromal layers in LTMC, although less sensitive to 4-HC cytotoxicity, were damaged by 4-HC also in a dose-related manner. Marrows treated with 4-HC up to 300 mumol/L, gave rise to stromal layers composed of fibroblasts, endothelial cells, adipocytes, and macrophages. Cocultivation experiments with freshly isolated autologous hematopoietic cells showed that stromal layers derived from 4-HC-treated marrows were capable of sustaining the long-term production of CFU-GM as well as controls

Spinor condensates and light scattering from Bose-Einstein condensates

These notes discuss two aspects of the physics of atomic Bose-Einstein condensates: optical properties and spinor condensates. The first topic includes light scattering experiments which probe the excitations of a condensate in both the free-particle and phonon regime. At higher light intensity, a new form of superradiance and phase-coherent matter wave amplification were observed. We also discuss properties of spinor condensates and describe studies of ground--state spin domain structures and dynamical studies which revealed metastable excited states and quantum tunneling.Comment: 58 pages, 33 figures, to appear in Proceedings of Les Houches 1999 Summer School, Session LXXI

Individuality and stability of the koala (Phascolarctos cinereus) faecal microbiota through time

Gut microbiota studies often rely on a single sample taken per individual, representing a snapshot in time. However, we know that gut microbiota composition in many animals exhibits intra-individual variation over the course of days to months. Such temporal variations can be a confounding factor in studies seeking to compare the gut microbiota of different wild populations, or to assess the impact of medical/veterinary interventions. To date, little is known about the variability of the koala (Phascolarctos cinereus) gut microbiota through time. Here, we characterise the gut microbiota from faecal samples collected at eight timepoints over a month for a captive population of South Australian koalas (n individuals = 7), and monthly over 7 months for a wild population of New South Wales koalas (n individuals = 5). Using 16S rRNA gene sequencing, we found that microbial diversity was stable over the course of days to months. Each koala had a distinct faecal microbiota composition which in the captive koalas was stable across days. The wild koalas showed more variation across months, although each individual still maintained a distinct microbial composition. Per koala, an average of 57 (±16) amplicon sequence variants (ASVs) were detected across all time points; these ASVs accounted for an average of 97% (±1.9%) of the faecal microbial community per koala. The koala faecal microbiota exhibits stability over the course of days to months. Such knowledge will be useful for future studies comparing koala populations and developing microbiota interventions for this regionally endangered marsupial.Raphael Eisenhofer, Kylie L. Brice, Michaela DJ Blyton, Scott E. Bevins, Kellie Leigh, Brajesh K. Singh, Kristofer M. Helgen, Ian Hough, Christopher B. Daniels, Natasha Speight and Ben D. Moor

Attentive Learning of Sequential Handwriting Movements: A Neural Network Model

Defense Advanced research Projects Agency and the Office of Naval Research (N00014-95-1-0409, N00014-92-J-1309); National Science Foundation (IRI-97-20333); National Institutes of Health (I-R29-DC02952-01)

Solum depth spatial prediction comparing conventional with knowledge-based digital soil mapping approaches

Solum depth and its spatial distribution play an important role in different types of environmental studies. Several approaches have been used for fitting quantitative relationships between soil properties and their environment in order to predict them spatially. This work aimed to present the steps required for solum depth spatial prediction from knowledge-based digital soil mapping, comparing the prediction to the conventional soil mapping approach through field validation, in a watershed located at Mantiqueira Range region, in the state of Minas Gerais, Brazil. Conventional soil mapping had aerial photo-interpretation as a basis. The knowledge-based digital soil mapping applied fuzzy logic and similarity vectors in an expert system. The knowledge-based digital soil mapping approach showed the advantages over the conventional soil mapping approach by applying the field expert-knowledge in order to enhance the quality of final results, predicting solum depth with suited accuracy in a continuous way, making the soil-landscape relationship explicit