The nuclear contacts and short range correlations in nuclei

Atomic nuclei are complex strongly interacting systems and their exact theoretical description is a long-standing challenge. An approximate description of nuclei can be achieved by separating its short and long range structure. This separation of scales stands at the heart of the nuclear shell model and effective field theories that describe the long-range structure of the nucleus using a mean- field approximation. We present here an effective description of the complementary short-range structure using contact terms and stylized two-body asymptotic wave functions. The possibility to extract the nuclear contacts from experimental data is presented. Regions in the two-body momentum distribution dominated by high-momentum, close-proximity, nucleon pairs are identified and compared to experimental data. The amount of short-range correlated (SRC) nucleon pairs is determined and compared to measurements. Non-combinatorial isospin symmetry for SRC pairs is identified. The obtained one-body momentum distributions indicate dominance of SRC pairs above the nuclear Fermi-momentum.Comment: Accepted for publication in Physics Letters. 6 pages, 2 figure

Zeta Potential of Modified Multi-walled Carbon Nanotubes in Presence of poly (vinyl alcohol) Hydrogel

The main objective of this study is investigate the behavior of the Zeta Potential of the MWCNT modified with SDS(Sodium Dodecyl Sulfate) and CTAB(Cetyl Tetraethyl Ammonium Bromide) in presence of PVA. Full hydrolyzed PVA was used. As a result, adding PVA in the CNT solution led to decrease the Zeta Potential. The Zeta Potential of suspended colloid varied from 42.00mV to 6.48mV and -45.00mV to -6.4mV at 1.5% concentration of PVA; according with the changing pH, the Zeta Potential dropped to near zero at pH 3 and 11. The pH and PVA has strong influence in the reduction of ZP of MWCNT solution. MWCNT-PVA solution with 33.30mV, -35.69mV at 0.01% of PVA was exposed under AC field; a uniform coat was obtained, with the SDS-MWCNT-PVA solution.National Natural Science Foundation of China Project (Grant No.51073024), the Royal Society-NSFC international joint project (Grant No.51111130207) and Beijing Municipal Science and Technology Plan Projects (No. Z111103066611005)

A wave-to-wire model for grid integration studies of oscillating-body wave energy converters

Wave energy converters (WECs) are still at an earlier stage of development when compared to variable renewable energy systems based on wind or solar power. Indeed, only a few WECs have exported power to electric grids until recently. Thus, the development of mathematical models able to represent essential aspects of the system and its connection to the grid becomes fundamental to assess the impact of integrating wave power to grids. This work develops a fully integrated wave-to-wire model, where the electrical model has re-configurable dynamic models of rotary and linear generators (with controllers) to accommodate different types of oscillating-body systems. Such an electrical model is interfaced with the WEC hydrodynamic and mechanical models. A complete wave-to-grid model is presented by integrating the generator system model, an electrical grid interface unit and a network equivalent for the receiving grid in a unified simulation environment with the WEC-Sim, an open-source tool for simulating the dynamic behaviour of WECs. Numerical simulation studies are presented considering different operating conditions for the grid integration of a floating body that is connected to either an hydraulic power take-off system or a direct-drive system.A wave-to-wire model for grid integration studies of oscillating-body wave energy convertersacceptedVersio

Cool Young Stars in the Northern Hemisphere: Beta Pictoris and AB Doradus Moving Group Candidates

As part of our continuing effort to identify new, low-mass members of nearby, young moving groups (NYMGs), we present a list of young, low-mass candidates in the northern hemisphere. We used our proven proper motion selection procedure and ROSAT-X-ray and GALEX-UV activity indicators to identify 204 young stars as candidate members of the Beta Pictoris and AB Doradus NYMGs. Definitive membership assignment of a given candidate will require a measurement of its radial velocity and distance. We present a simple system of indices to characterize the young candidates and help prioritize follow up observations. New group members identified in this candidate list will be high priority targets for: 1) exoplanet direct imaging searches, 2) the study of post-T-Tauri astrophysics, 3) understanding recent local star formation, and 4) the study of local galactic kinematics. Information available now allows us to identify 8 likely new members in the list. Two of these, a late-K and an early-M dwarf, we find to be likely members of the Beta Pic group. The other six stars are likely members of the AB Dor moving group. These include an M dwarf triple system, and three very cool objects that may be young brown dwarfs, making them the lowest-mass, isolated objects proposed in the AB Dor moving group to date.Comment: 41 pages, 15 figures, Accepted to the Astronomical Journa

An Infrared/X-ray Survey for New Members of the Taurus Star-Forming Region

We present the results of a search for new members of the Taurus star-forming region using data from the Spitzer Space Telescope and the XMM-Newton Observatory. We have obtained optical and near-infrared spectra of 44 sources that exhibit red Spitzer colors that are indicative of stars with circumstellar disks and 51 candidate young stars that were identified by Scelsi and coworkers using XMM-Newton. We also performed spectroscopy on four possible companions to members of Taurus that were reported by Kraus and Hillenbrand. Through these spectra, we have demonstrated the youth and membership of 41 sources, 10 of which were independently confirmed as young stars by Scelsi and coworkers. Five of the new Taurus members are likely to be brown dwarfs based on their late spectral types (>M6). One of the brown dwarfs has a spectral type of L0, making it the first known L-type member of Taurus and the least massive known member of the region (M=4-7 M_Jup). Another brown dwarf exhibits a flat infrared spectral energy distribution, which indicates that it could be in the protostellar class I stage (star+disk+envelope). Upon inspection of archival images from various observatories, we find that one of the new young stars has a large edge-on disk (r=2.5=350 AU). The scattered light from this disk has undergone significant variability on a time scale of days in optical images from the Canada-France-Hawaii Telescope. Using the updated census of Taurus, we have measured the initial mass function for the fields observed by XMM-Newton. The resulting mass function is similar to previous ones that we have reported for Taurus, showing a surplus of stars at spectral types of K7-M1 (0.6-0.8 M_sun) relative to other nearby star-forming regions like IC 348, Chamaeleon I, and the Orion Nebula Cluster

Laser Calibration System for Time of Flight Scintillator Arrays

A laser calibration system was developed for monitoring and calibrating time of flight (TOF) scintillating detector arrays. The system includes setups for both small- and large-scale scintillator arrays. Following test-bench characterization, the laser system was recently commissioned in experimental Hall B at the Thomas Jefferson National Accelerator Facility for use on the new Backward Angle Neutron Detector (BAND) scintillator array. The system successfully provided time walk corrections, absolute time calibration, and TOF drift correction for the scintillators in BAND. This showcases the general applicability of the system for use on high-precision TOF detectors.Comment: 11 pages, 11 figure

Growth dynamics of morphological and reproductive traits of Physalis peruviana L. M1 plants obtained from seeds irradiated with gamma rays

There is an increasing interest in the development of uchuva (Physalis peruviana L.) cultivars adapted to greenhouse farming. Sexual behavior makes it difficult to obtain uniform commercial uchuva cultivars by conventional breeding methods. Mutations induced by gamma rays is an alternative approach. M1 plants derived from 14 irradiation 60Co doses, from 0 to 275 Gy, that were applied to uchuva seeds were evaluated. Recorded data included days to first flower and growth dynamics (four to seven samplings) of morphological traits (plant height, stem diameter, basal stems) and reproductive traits (floral buds, flowers and green fruits). Treatments were distributed in a completely randomized blocks experimental design with six replications, in a greenhouse. The experimental unit was a single M1 plant. Statistical differences were found for irradiation doses, growth samplings, and its interaction. Growth dynamics results indicate that all traits showed a linear increase with plant age (R2 = 0.92* to 0.98**), but the effect of the irradiation doses on morphological and reproductive traits was no linear. Irradiation reduced plant height by 79%. M1 plants developed from irradiated seeds at doses of 125, 175 and 200 Gy showed greater stem diameter, with more basal stems, floral buds, flowers and green fruits than the control. It is concluded that intermediate irradiation doses had a stimulating effect on vegetative growth and fruiting traits of M1 uchuva plants

Hearing loss due to noise exposure and its relationship with hypertension in Peruvian workers

Introduction:Noise-induced hearing loss has been implicated in the genesis of several chronic conditions; however, its behavior concerning hypertension still raises doubts about it.Objective:to determine the association between hearing loss due to exposure to noise and the presence of hypertension in a sample of Peruvian workers.Methods: Cross-sectional analytical study. Secondary analysis of the occupational database of a Medical centerin Lima, Peru. hypertensionwas measured by self-report and clinical method. Hearing loss was classified as none, mild, moderate and severe. For the regression analysis, Poisson was performed with robust variance, obtaining crude (PRc) and adjusted (PRa) prevalence ratios.Results: We worked with a total of 1987 participants. The prevalence of hypertension was 15.40% and hearing loss was 36.39%. For the multivariate regression analysis, a statistically significant association with hypertension was found in those with mild hearing loss (PRa=1.52; CI95% 1.06–2.10), moderate (PRa=2.70; CI95% 1,93–3.76) and severe (PRa=3.82; 95% CI 2.56–5.96), compared to those without hearing loss.Conclusions:Hearing loss due to exposure to occupational noise was associated with the presence of hypertension. Although this study is only a first overview of the relationship that both variables could have, it is recommended to continue promoting policies and awareness campaigns to prevent hearing loss in workers, and thus avoid complications related to it in the long term.Campus Lima Nort

Hearing Loss due to Noise Exposure and its Relationship with Hypertension in Peruvian Workers

Introduction: Noise-induced hearing loss has been implicated in the genesis of several chronic conditions; however, its behavior concerning hypertension still raises doubts about it. Objective: to determine the association between hearing loss due to exposure to noise and the presence of hypertension in a sample of Peruvian workers. Methods: Cross-sectional analytical study. Secondary analysis of the occupational database of a Medical center in Lima, Peru. hypertension was measured by self-report and clinical method. Hearing loss was classified as none, mild, moderate and severe. For the regression analysis, Poisson was performed with robust variance, obtaining crude (PRc) and adjusted (PRa) prevalence ratios. Results: We worked with a total of 1987 participants. The prevalence of hypertension was 15.40% and hearing loss was 36.39%. For the multivariate regression analysis, a statistically significant association with hypertension was found in those with mild hearing loss (PRa=1.52; CI95% 1.06–2.10), moderate (PRa=2.70; CI95% 1,93–3.76) and severe (PRa=3.82; 95% CI 2.56–5.96), compared to those without hearing loss. Conclusions: Hearing loss due to exposure to occupational noise was associated with the presence of hypertension. Although this study is only a first overview of the relationship that both variables could have, it is recommended to continue promoting policies and awareness campaigns to prevent hearing loss in workers, and thus avoid complications related to it in the long term