Calculation of nanowire thermal conductivity using complete phonon dispersion relations

The lattice thermal conductivity of crystalline Si nanowires is calculated. The calculation uses complete phonon dispersions, and does not require any externally imposed frequency cutoffs. No adjustment to nanowire thermal conductivity measurements is required. Good agreement with experimental results for nanowires wider than 35 nm is obtained. A formulation in terms of the transmission function is given. Also, the use of a simpler, nondispersive "Callaway formula", is discussed from the complete dispersions perspective.Comment: 4 pages, 3 figures. Accepted in Phys. Rev.

Prognostic classification for malignant tumors of the parotid gland

AbstractObjectiveThe histological classification of the World Health Organization (WHO), along with improved imaging studies, provide relevant information for the management of parotid carcinomas. However, the prognosis depends on factors other than histology and tumor extension. This article evaluates the usefulness of a prognostic classification of parotid cancers, including these factors in patients in a hospital area.MethodsA follow-up was conducted on 19 patients with parotid carcinomas, excluding lymphoid tumors or intra-parotid metastases, between 1998 and 2012. The prognostic index was obtained from the formulas proposed by Vander Poorten, with factors including age, tumor size, lymph node involvement, skin invasion, facial nerve involvement, perineural growth and margins of resection, before surgery (PS1) and after (PS2). Overall survival was related to 5 years for each patient based on their inclusion in any of the 4 risk groups defined.ResultsRisk stratification based on the results Vander Poorten PS2 was distributed into Risk Groups (GR) 1 (3 patients, 15.7%), 2 (5 patients, 26.3%), 3 (1 patient, 5.8%) and 4 (10 patients, 52.2%). The 6 patients who died during follow-up belonged to GR4. Only one of the 4 patients belonging to GR4 has exceeded the 5-year survival up to the current time.The comparison of the values that relate the pretreatment (PS1) and after treatment (PS2) results showed overall survival in patients with PS1<4.5 and PS2<4.9, whereas mortality was greater with indices of PS1>6.5 and PS2>7.7.ConclusionsVander Poorten index can be applied in hospital areas with small numbers of parotid carcinomas. It enables a more accurate prognosis for individual patients

Clusters’ far-reaching influence on narrow-angle tail radio galaxies

In order to study the ram-pressure interaction between radio galaxies and the intracluster medium, we analyse a sample of 208 highly-bent narrow-angle tail radio sources (NATs) in clusters, detected by the LOFAR Two-metre Sky Survey. For NATs within 7 R500 of the cluster centre, we find that their tails are distributed anisotropically with a strong tendency to be bent radially away from the cluster, which suggests that they are predominantly on radially inbound orbits. Within 0.5 R500, we also observe an excess of NATs with their jets bent towards the cluster core, indicating that these outbound sources fade away soon after passing pericentre. For the subset of NATs with spectroscopic redshifts, we find the radial bias in the jet angles exists even out to 10 R500, far beyond the virial radius. The presence of NATs at such large radii implies that significant deceleration of the accompanying inflowing intergalactic medium must be occurring there to create the ram pressure that bends the jets, and potentially even triggers the radio source

Physical performance and quality of life in older adults: Is there any association between them and potential drug interactions in Polymedicated Octogenarians?

Producción CientíficaOlder adults are at increased risk of several cytochrome P450 (CYP) drug interactions that can result in drug toxicity, reduced pharmacological effect, and adverse drug reactions. This study aimed to assess the prevalence of potential CYP interactions referring to the most clinically relevant drugs and exploring the relationship between them and quality of life and physical performance in Spanish octogenarians. Institutionalized and community-dwelling octogenarians (n = 102) treated at three primary care centers, were recruited by a research nurse. Anthropometric measurements, chronic diseases, prescribed drugs, quality of life, physical performance, mobility skills, hand grip strength and cognitive status data were collected. Potential CYP drug-drug interactions (DDIs) were selected referring to the main CYP implicated in their metabolism. The 72.2% of recruited octogenarians presented potentially inappropriate CYP inhibitor-substrate or CYP inductor-substrate combinations. Analyzing the EuroQol Visual Analogue scale (EQ-VAS) results, patients with a potential CYP DDI perceived worse health status than patients without it (p = 0.004). In addition, patients with a potential CYP DDI presented worse exercise capacity, kinesthetic abilities, or mobility than those who didn’t present a potential interaction (p = 0.01, p = 0.047, and p = 0.02, respectively). To investigate and control factors associated with loss of muscle strength and poor quality of life, polypharmacy and DDIs could help institutions in the management of physical frailty.Fundación Científica Caja Rural de Soria (project 00200200227

Surface Screening Charge and Effective Charge

The charge on an atom at a metallic surface in an electric field is defined as the field-derivative of the force on the atom, and this is consistent with definitions of effective charge and screening charge. This charge can be found from the shift in the potential outside the surface when the atoms are moved. This is used to study forces and screening on surface atoms of Ag(001) c$(2\times 2)$ -- Xe as a function of external field. It is found that at low positive (outward) fields, the Xe with a negative effective charge of -0.093 $|{e}|$ is pushed into the surface. At a field of 2.3 V \AA$^{-1}$ the charge changes sign, and for fields greater than 4.1 V \AA$^{-1}$ the Xe experiences an outward force. Field desorption and the Eigler switch are discussed in terms of these results.Comment: 4 pages, 1 figure, RevTex (accepted by PRL

Cosmic evolution of FRI and FRII sources out to z=2.5

Radio-loud active galactic nuclei (RLAGN) play an important role in the evolution of galaxies through the effects on their environment. The two major morphological classes are core-bright (FRI) and edge-bright (FRII) sources. With the LOw-Frequency ARray (LOFAR) we compare the FRI and FRII evolution down to lower flux densities and with larger samples than before with the aim to examine the cosmic space density evolution for FRIs and FRIIs by analyzing their space density evolution between L_150~10^24.5 W/Hz and L_150~10^28.5 W/Hz and up to z=2.5. We construct radio luminosity functions (RLFs) from FRI and FRII catalogues based on recent data from LOFAR at 150MHz to study the space densities as a function of radio luminosity and redshift. To partly correct for selection biases and completeness, we simulate how sources appear at a range of redshifts. We report a space density enhancement from low to high redshift for FRI and FRII sources brighter than L_150~10^27 W/Hz. This is possibly related to the higher gas availability in the earlier denser universe. The constant FRI/FRII space density ratio evolution as a function of radio luminosity and redshift in our results suggests that the jet-disruption of FRIs might be primarily caused by events occurring on scales within the host galaxy, rather than being driven by changes in the overall large-scale environment. Remaining selection biases in our results also highlight the need to resolve more sources at angular scales below 40 arcsec and therefore strengthens the motivation for the further development and automation of the calibration and imaging pipeline of LOFAR data to produce images at sub-arcsecond resolution

Generating random quantum channels

Several techniques of generating random quantum channels, which act on the set of $d$-dimensional quantum states, are investigated. We present three approaches to the problem of sampling of quantum channels and show under which conditions they become mathematically equivalent, and lead to the uniform, Lebesgue measure on the convex set of quantum operations. We compare their advantages and computational complexity and demonstrate which of them is particularly suitable for numerical investigations. Additional results focus on the spectral gap and other spectral properties of random quantum channels and their invariant states. We compute mean values of several quantities characterizing a given quantum channel, including its unitarity, the average output purity and the $2$-norm coherence of a channel, averaged over the entire set of the quantum channels with respect to the uniform measure. An ensemble of classical stochastic matrices obtained due to super-decoherence of random quantum stochastic maps is analyzed and their spectral properties are studied using the Bloch representation of a classical probability vector.Comment: 29 pages, 7 figure

The LOFAR LBA Sky Survey II. First data release

The Low Frequency Array (LOFAR) is the only existing radio interferometer able to observe at ultra-low frequencies (<100 MHz) with high resolution (<15") and high sensitivity (<1 mJy/beam). To exploit these capabilities, the LOFAR Surveys Key Science Project is using the LOFAR Low Band Antenna (LBA) to carry out a sensitive wide-area survey at 41-66 MHz named the LOFAR LBA Sky Survey (LoLSS). LoLSS is covering the whole northern sky above declination 24 deg with a resolution of 15" and a sensitivity of 1-2 mJy/beam (1 sigma) depending on declination, field properties, and observing conditions. Here we present the first data release. An automated pipeline was used to reduce the 95 fields included in this data release. The data reduction procedures developed for this project have general application and are currently being used to process LOFAR LBA interferometric observations. Compared to the preliminary release, direction-dependent errors have been corrected for during the calibration process. This results in a typical sensitivity of 1.55 mJy/beam at the target resolution of 15". The first data release of the LOFAR LBA Sky Survey covers 650 sqdeg in the HETDEX spring field. The resultant data products released to the community include mosaic images (I and V Stokes) of the region, and a catalogue of 42463 detected sources and related Gaussian components used to describe sources' morphologies. Separate catalogues for 6 in-band frequencies are also released. The first data release of LoLSS shows that, despite the influences of the ionosphere, LOFAR can conduct large-scale surveys in the frequency window 42-66 MHz with unprecedentedly high sensitivity and resolution. The data can be used to derive unique information on the low-frequency spectral properties of many thousands of sources with a wide range of applications in extragalactic and galactic astronomy.Comment: 20 pages, 22 figures, images and catalogues available at https://www.lofar-surveys.org/lolss.htm

The MIXR sample: AGN activity versus star formation across the cross-correlation of WISE, 3XMM, and FIRST/NVSS

We cross-correlate the largest available mid-infrared (Wide-field Infrared Survey Explorer - WISE), X-ray (3XMM) and radio (Faint Images of the Radio Sky at Twenty centimetres+NRAO VLA Sky Survey) catalogues to define the MIXR sample of AGN and star-forming galaxies. We pre-classify the sources based on their positions on the WISE colour/colour plot, showing that the MIXR triple selection is extremely effective to diagnose the star formation and AGN activity of individual populations, even on a flux/magnitude basis, extending the diagnostics to objects with luminosities and redshifts from SDSS DR12. We recover the radio/mid-IR star formation correlation with great accuracy, and use it to classify our sources, based on their activity, as radio-loud and radio-quiet active galactic nuclei (AGN), low excitation radio galaxies/low ionization nuclear emission line regions, and non-AGN galaxies. These diagnostics can prove extremely useful for large AGN and galaxy samples, and help develop ways to efficiently triage sources when data from the next generation of instruments becomes available. We study bias in detail, and show that while the widely used WISE colour selections for AGN are very successful at cleanly selecting samples of luminous AGN, they miss or misclassify a substantial fraction of AGN at lower luminosities and/or higher redshifts. MIXR also allows us to test the relation between radiative and kinetic (jet) power in radio-loud AGN, for which a tight correlation is expected due to a mutual dependence on accretion. Our results highlight that long-term AGN variability, jet regulation, and other factors affecting the Q/Lbol relation, are introducing a vast amount of scatter in this relation, with dramatic potential consequences on our current understanding of AGN feedback and its effect on star formation