Identification of hydrogen bonds using quantum electrodynamics

A method for the identification of hydrogen bonds was investigated from the viewpoint of the stress tensor density proposed by Tachibana and following other works in this field. Hydrogen bonds are known to exhibit common features with ionic and covalent bonds. In quantum electrodynamics, the covalent bond has been demonstrated to display a spindle structure of the stress tensor density. Importantly, this spindle structure is also seen in the hydrogen bond, although the covalency is considerably weaker than in a typical covalent bond. Distinguishing it from the ionic bond is most imperative for the identification of the hydrogen bond. In the present study, the directionality of the hydrogen bond is investigated as the ionic bond is nearly isotropic, while the hydrogen bond exhibits the directionality. It was demonstrated that the hydrogen bond can be distinguished from the ionic bond using the angle dependence of the largest eigenvalue of the stress tensor density

Oncologic outcomes following surgical management of clinical stage II sex cord stromal tumors

Objective To investigate the clinical history of patients with clinical stage II sex cord stromal tumors who underwent RPLND at our institution. Methods Our prospectively maintained testicular cancer database was queried to identify patients who presented with or developed clinical stage II sex cord stromal tumors and underwent RPLND at our institution between 1980 and 2018. Demographic, clinical and pathological characteristics were reviewed. Kaplan-Meier curves were graphed to assess recurrence-free and overall survival. Results Fourteen patients were included in the study with a median age of 44.2 years. Four patients presented with clinical stage II disease and 10 patients developed metastatic disease during follow-up of initial clinical stage I disease with a median time to metastasis of 2.7 years (range: 0.4-19.5 years). Of the 10 patients with orchiectomy pathology data available, all patients had at least 1 risk factor on testis pathology (mean: 2.9 risk factors). Nine patients received treatment prior to referral to our institution. All patients recurred post-RPLND at Indiana University. Median recurrence-free survival was 9.8 months. Twelve patients died of disease with a median overall survival of 14.4 months. Conclusions Metastatic sex cord stromal tumors are rare and are more resistant to standard treatment modalities than metastatic germ cell tumors. Patients presenting with sex cord stromal tumors should consider prophylactic primary RPLND in the setting of one or more pathological predictor of malignancy

A Morphological Classification Model to Identify Unresolved PanSTARRS1 Sources: Application in the ZTF Real-Time Pipeline

In the era of large photometric surveys, the importance of automated and accurate classification is rapidly increasing. Specifically, the separation of resolved and unresolved sources in astronomical imaging is a critical initial step for a wide array of studies, ranging from Galactic science to large scale structure and cosmology. Here, we present our method to construct a large, deep catalog of point sources utilizing Pan-STARRS1 (PS1) 3$\pi$ survey data, which consists of $\sim$3$\times10^9$ sources with $m\lesssim23.5\,$mag. We develop a supervised machine-learning methodology, using the random forest (RF) algorithm, to construct the PS1 morphology model. We train the model using $\sim$5$\times10^4$ PS1 sources with HST COSMOS morphological classifications and assess its performance using $\sim$4$\times10^6$ sources with Sloan Digital Sky Survey (SDSS) spectra and $\sim$2$\times10^8$ \textit{Gaia} sources. We construct 11 "white flux" features, which combine PS1 flux and shape measurements across 5 filters, to increase the signal-to-noise ratio relative to any individual filter. The RF model is compared to 3 alternative models, including the SDSS and PS1 photometric classification models, and we find that the RF model performs best. By number the PS1 catalog is dominated by faint sources ($m\gtrsim21\,$mag), and in this regime the RF model significantly outperforms the SDSS and PS1 models. For time-domain surveys, identifying unresolved sources is crucial for inferring the Galactic or extragalactic origin of new transients. We have classified $\sim$1.5$\times10^9$ sources using the RF model, and these results are used within the Zwicky Transient Facility real-time pipeline to automatically reject stellar sources from the extragalactic alert stream.Comment: Published in PASP Focus Issue on the Zwicky Transient Facility (doi: 10.1088/1538-3873/aae3d9). 17 Pages, 9 Figure

Electronic stress tensor analysis of hydrogenated palladium clusters

We study the chemical bonds of small palladium clusters Pd_n (n=2-9) saturated by hydrogen atoms using electronic stress tensor. Our calculation includes bond orders which are recently proposed based on the stress tensor. It is shown that our bond orders can classify the different types of chemical bonds in those clusters. In particular, we discuss Pd-H bonds associated with the H atoms with high coordination numbers and the difference of H-H bonds in the different Pd clusters from viewpoint of the electronic stress tensor. The notion of "pseudo-spindle structure" is proposed as the region between two atoms where the largest eigenvalue of the electronic stress tensor is negative and corresponding eigenvectors forming a pattern which connects them.Comment: 22 pages, 13 figures, published online, Theoretical Chemistry Account

Color Superconductivity from Supersymmetry

A supersymmetric composite model of color superconductivity is proposed. Quarks and diquarks are dynamically generated as composite fields by a newly introduced strong gauge dynamics. It is shown that the condensation of the scalar component of the diquark supermultiplet occurs when the chemical potential becomes larger than some critical value. We believe that the model well captures aspects of the diquark condensate behavior and helps our understanding of the diquark dynamics in real QCD. The results obtained here might be useful when we consider a theory composed of quarks and diquarks.Comment: 4 pages, 2 figures, An error in Eq.(10) correcte

Bonding in doped gallium nanoclusters: Insights from regional DFT

The molecular nature (Ga2)n of gallium makes this an interesting metal to investigate for the development of novel nano-materials. However, establishment of a targeted approach to manipulating the properties of gallium clusters requires a detailed understanding of how doping affects the bonding in these species. In this study, the bonding of gallium nanoclusters has been investigated using electron deformation densities and Regional Density Functional Theory (RDFT). Bonding throughout Ga12X clusters is generally intermediate between covalent and metallic. However, the presence of Ga2 subunits is clearly identified in clusters with endohedral dopants (Ga12X, X = Al, Si, P, Ga, Ge, As). Although there is evidence of Ga2 subunits in exohedral doped clusters, localised bonding to the dopant generally leads to significant disruption to the cluster framework. Maps of electronic chemical potential provide understanding for the observed differences in regioselectivity for hydrogen adsorption

Common snook fed in alternate and continuous regimens with diet supplemented with Bacillus subtilis probiotic.

The objective of this work was to evaluate the addition of Bacillus subtilis probiotic to the feed of common snook (Centropomus undecimalis) fingerlings, in alternate and continuous regimens. Six hundred and sixty fish, with verage length of 5.90±0.88 cm and weight of 1.92±0.28g, were stocked in 12 cages of 1.0 m 3 , with 55 fish each. The experimental design was completely randomized, with three treatments and four replicates. The treatments consisted of diet with the addition of probiotic, provided in alternate regimen for 7 days and in continuous regimen; besides a control without probiotic in the feed. Zootechnical performance, body composition, immune response, and blood parameters were evaluated. No significant differences were observed in zootechnical performance indexes and in body composition of fish treated with probiotic, when compared to the control. Fish from the alternate regimen showed an increment in respiratory burst and a lower total erythrocyte count than fish from the continuous regimen and the control. Fish from the continuous regimen did not differ from those of the control. The addition of Bacillus subtilis does not increase growth rates of common snook fingerlings; however, it has an immunostimulant action when supplied in alternate regimen.Título em português: Robalo?flecha alimentado em regimes alternado e contínuo com dieta suplementada com o probiótico Bacillus subtilis

Simultaneous Triggered Collapse of the Presolar Dense Cloud Core and Injection of Short-Lived Radioisotopes by a Supernova Shock Wave

Cosmochemical evidence for the existence of short-lived radioisotopes (SLRI) such as $^{26}$Al and $^{60}$Fe at the time of the formation of primitive meteorites requires that these isotopes were synthesized in a massive star and then incorporated into chondrites within $\sim 10^6$ yr. A supernova shock wave has long been hypothesized to have transported the SLRI to the presolar dense cloud core, triggered cloud collapse, and injected the isotopes. Previous numerical calculations have shown that this scenario is plausible when the shock wave and dense cloud core are assumed to be isothermal at $\sim 10$ K, but not when compressional heating to $\sim 1000$ K is assumed. We show here for the first time that when calculated with the FLASH2.5 adaptive mesh refinement (AMR) hydrodynamics code, a 20 km/sec shock wave can indeed trigger the collapse of a 1 $M_\odot$ cloud while simultaneously injecting shock wave isotopes into the collapsing cloud, provided that cooling by molecular species such as H$_2$O, CO$_2$, and H$_2$ is included. These calculations imply that the supernova trigger hypothesis is the most likely mechanism for delivering the SLRI present during the formation of the solar system.Comment: 12 pages, 4 color figures. Astrophysical Journal Letters (in press