D Mesons in Nuclear Matter: A DN Coupled-Channel Equations Approach

A set of coupled two-body scattering equations is solved for the DN system embedded in an iso-symmetric nuclear matter. The in-medium behavior of charmed D mesons: (D^+,D^0), is investigated from the self-consistent solution within this scheme. The effective meson-baryon Lagrangian in charm quantum number one sector, the key ingredient in the present study, is adopted from a recent model by Hofmann and Lutz which has aimed at combining the charmed meson degree of freedom in a consistent manner with chiral unitary models. After a critical examination, the original model is modified in several important aspects, such as the method of regularization, in order to be more consistent and practical for our objective. The resultant interaction is used to reproduce the position and width of the s-wave \Lambda_c(2593) resonance in the isospin zero DN channel. In the isospin one channel, it generates a rather wide resonance at \~2770 MeV. The corresponding in-medium solution is then sought by incorporating Pauli blocking and the D- and \pi-meson dressing self-consistently. At normal nuclear matter density, the resultant \Lambda_c (2593) is found to stay narrow and shifted at a lower energy, while the I=1 resonance is lowered in position as well and broadened considerably. The possible implication of our findings on the J/\Psi suppression, etc. in relativistic heavy ion collisions is briefly discussed.Comment: 30 pages, 8 eps figures, some typos and coefficients corrected, published in Phys. Rev.

Room temperature and low-field resonant enhancement of spin Seebeck effect in partially compensated magnets

Resonant enhancement of spin Seebeck effect (SSE) due to phonons was recently discovered in Y3Fe5O12 (YIG). This effect is explained by hybridization between the magnon and phonon dispersions. However, this effect was observed at low temperatures and high magnetic fields, limiting the scope for applications. Here we report observation of phonon-resonant enhancement of SSE at room temperature and low magnetic field. We observed in Lu2BiFe4GaO12 and enhancement 700 % greater than that in a YIG film and at very low magnetic fields around 10-1 T, almost one order of magnitude lower than that of YIG. The result can be explained by the change in the magnon dispersion induced by magnetic compensation due to the presence of non-magnetic ion substitutions. Our study provides a way to tune the magnon response in a crystal by chemical doping with potential applications for spintronic devices.Comment: 17 pages, 4 figure

Convex Independence in Permutation Graphs

A set C of vertices of a graph is P_3-convex if every vertex outside C has at most one neighbor in C. The convex hull \sigma(A) of a set A is the smallest P_3-convex set that contains A. A set M is convexly independent if for every vertex x \in M, x \notin \sigma(M-x). We show that the maximal number of vertices that a convexly independent set in a permutation graph can have, can be computed in polynomial time

Biodiversidade e reforma agrária: uma experiência agroecolócica na região canavieira de Ribeirão Preto, Brasil.

A região de Ribeirão Preto, norte do estado de São Paulo, Brasil, se caracteriza pelo predomínio da monocultura da cana de açúcar, com grande impacto ambiental negativo sobre o Aqüífero Guarani. Visando conciliar a demanda social por terra e a preservação ambiental, em 2004 foi implantado na região um assentamento de reforma agrária, apoiado na matriz tecnológica da agroecologia. O artigo irá descrever e analisar este processo sob a ótica da construção de um novo modelo de desenvolvimento para região

In an octopus's garden in the shade: Underwater image analysis of litter use by benthic octopuses

Benthic octopuses have been widely documented in artificial shelters for decades, and this use is apparently increasing. Despite any possible positive effects, the use of litter as shelter could have negative implications. In this work, we aimed to elucidate the interactions of octopuses with marine litter, identifying types of interactions and affected species and regions. To achieve this, we obtained 261 underwater images from ‘citizen science’ records, and identified 8 genera and 24 species of benthic octopuses interacting with litter. Glass objects were present in 41.6% of interactions, and plastic in 24.7%. Asia presented the highest number of images, and most records were from 2018 to 2021. Citizen science provided important evidence on octopus/marine litter interactions, highlighting its value and the need for more investigations on the subject. This information is fundamental to help prevent and mitigate the impacts of litter on octopuses, and identify knowledge gaps that require attention

Towards a fully self-consistent spectral function of the nucleon in nuclear matter

We present a calculation of nuclear matter which goes beyond the usual quasi-particle approximation in that it includes part of the off-shell dependence of the self-energy in the self-consistent solution of the single-particle spectrum. The spectral function is separated in contributions for energies above and below the chemical potential. For holes we approximate the spectral function for energies below the chemical potential by a $\delta$-function at the quasi-particle peak and retain the standard form for energies above the chemical potential. For particles a similar procedure is followed. The approximated spectral function is consistently used at all levels of the calculation. Results for a model calculation are presented, the main conclusion is that although several observables are affected by the inclusion of the continuum contributions the physical consistency of the model does not improve with the improved self-consistency of the solution method. This in contrast to expectations based on the crucial role of self-consistency in the proofs of conservation laws.Comment: 26 pages Revtex with 4 figures, submitted to Phys. Rev.

A Rare Case Report of a Testicular Germ-Cell Tumor (GCT) Metastasis Mimicking Pancreatic Malignancy

Introduction: Testicular germ cell tumors (TGCT), evenly divided into two histologic types, seminomas and nonseminomas, are the most common malignancy among males between ages 15 to 44 years [1, 2]. The incidence of TGCT in the U.S. has increased over the past 20 years, being attributed to chronic exposure environmental risk factors (i.e. pesticides and plastic component polyvinyl chloride) in addition to genetic predisposition [1, 3-6]. Description: We report of an unusual case of retroperitoneal metastatic GCT clinically simulating a pancreatic lymphoma. A 31-year-old male presented with a 2-month history of abdominal pain in the right upper quadrant, 40-pound weight loss, nausea, episodes of emesis and decreased appetite. Abdominal computed tomography scan showed a large heterogenous mass measuring 11 x 8 cm in close proximity to the head and body of the pancreas. This tumor encased portions of the celiac trunk, superior mesenteric artery, splenic, superior mesenteric and portal veins. Additional solid masses measuring 8.2 cm and 10 x 8.8 cm were noted inferior to porta hepatis and medial to the left kidney, respectively. Given the tumor distribution, patient was suspected of having pancreatic lymphoma and underwent endoscopic ultrasound-guided tissue sampling of the tumor. Microscopic examination of the biopsy revealed solid nests of infiltrative malignant epitheloid cells characterized by nuclear pleomorphisms and hyperchromatic nuclei with focal necrotic and apoptotic debris. Immunohistochemical stains revealed positive pancytokeratin and SALL4, a transcription factor specific for embryonic cell pluripotency and an immunohistochemical marker for TGCT [7]. Laboratory tests revealed elevated serum levels of alpha fetoprotein (AFP = 57.8 ng/ml; reference: 10-20 ng/ml), lactate dehydrogenase (LDH = 2919 units/L; reference:106-242 units/L) and beta human chronic gonadotrophin (β-hCG =1458 IU/L; reference: 0-3 IU/L). Both microscopic and laboratory findings are consistent with metastatic retroperitoneal GCT. Subsequent clinical history and physical exam of the patient revealed a right testicular solid mass measuring 13.3 x 7.8 x 10.7 cm. Patient was aware of this progressively enlarging right testicular mass for the past 5-years, but had not undergone previous evaluation. Patient’s family history is negative for TGCT and denied undergoing orchiopexy for cryptorchidism during his childhood. Patient has been working in a plastic manufacturing company with exposure to endocrine disrupting chemicals, a potential exogenous risk factor for his TGCT [5]. Conclusion: Final diagnosis was “Stage IIIA-Testicular GCT-Low-risk” based on the primary and metastatic sites involvement and serum tumor marker levels. The patient underwent radical orchiectomy of the right testicle followed by 4 cycles of chemotherapy with etoposide/cisplatin/bleomycin for the remaining retroperitoneal tumors. The five-year progression-free and overall survival rate for our patient are 89% and 92%, respectively [1]. This case highlights an unusual presentation of retroperitoneal GCT metastasis and the need to include the following differentials of lymphoma, sarcoma, and GCT for retroperitoneal masses with lymphadenopathy

Ion-beam mixing induced by atomic and cluster bombardment in the electronic stopping-power regime

Single crystals of magnesium oxide containing nanoprecipitates of sodium were bombarded with swift ions (∼GeV-Pb, U) or cluster beams (∼20 MeV-C60) to study the phase change induced by electronic processes at high stopping power (≳10 keV/nm). The sodium precipitates and the defect creation were characterized by optical absorption and transmission electron microscopy. The ion or cluster bombardment leads to an evolution of the Na precipitate concentration but the size distribution remains unchanged. The decrease in Na metallic concentration is attributed to mixing effects at the interfaces between Na clusters and MgO. In addition, optical-absorption measurements show a broadening of the absorption band associated with electron plasma oscillations in Na clusters. This effect is due to a decrease of the electron mean free path, which could be induced by defect creation in the metal. All these results show an influence of high electronic stopping power in materials known to be very resistant to irradiation with weak ionizing projectiles. The dependence of these effects on electronic stopping power and on various solid-state parameters is discussed