Helium mixtures in nanotube bundles

An analogue to Raoult's law is determined for the case of a 3He-4He mixture adsorbed in the interstitial channels of a bundle of carbon nanotubes. Unlike the case of He mixtures in other environments, the ratio of the partial pressures of the coexisting vapor is found to be a simple function of the ratio of concentrations within the nanotube bundle.Comment: 3 pages, no figures, submitted to Phys. Rev. Let

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

Several Yeast Species Induce Iron Deficiency Responses in Cucumber Plants (Cucumis sativus L.)

Iron (Fe) deficiency is a first-order agronomic problem that causes a significant decrease in crop yield and quality. Paradoxically, Fe is very abundant in most soils, mainly in its oxidized form, but is poorly soluble and with low availability for plants. In order to alleviate this situation, plants develop different morphological and physiological Fe-deficiency responses, mainly in their roots, to facilitate Fe mobilization and acquisition. Even so, Fe fertilizers, mainly Fe chelates, are widely used in modern agriculture, causing environmental problems and increasing the costs of production, due to the high prices of these products. One of the most sustainable and promising alternatives to the use of agrochemicals is the better management of the rhizosphere and the beneficial microbial communities presented there. The main objective of this research has been to evaluate the ability of several yeast species, such as Debaryomyces hansenii, Saccharomyces cerevisiae and Hansenula polymorpha, to induce Fe-deficiency responses in cucumber plants. To date, there are no studies on the roles played by yeasts on the Fe nutrition of plants. Experiments were carried out with cucumber plants grown in a hydroponic growth system. The effects of the three yeast species on some of the most important Fe-deficiency responses developed by dicot (Strategy I) plants, such as enhanced ferric reductase activity and Fe2+ transport, acidification of the rhizosphere, and proliferation of subapical root hairs, were evaluated. The results obtained show the inductive character of the three yeast species, mainly of Debaryomyces hansenii and Hansenula polymorpha, on the Fe-deficiency responses evaluated in this study. This opens a promising line of study on the use of these microorganisms as Fe biofertilizers in a more sustainable and environmentally friendly agriculture

Estudio teórico y experimental de la respuesta a cortante en juntas secas de puentes de dovelas

En este artículo se presentan los estudios realizados en el proyecto de investigación PB98-0927 financiado por el Ministerio de Educación y Cultura en el periodo 1999 a 2002. En este proyecto se ha realizado una extensa campaña experimental, así como un profundo estudio teórico, del comportamiento en ELU, frente a solicitaciones combinadas de cortante y flexión, de juntas secas en puentes construidos mediante dovelas prefabricadas.Peer ReviewedPostprint (published version

Wideband tunable microwave signal generation in a silicon-based optoelectronic oscillator

Si photonics has an immense potential for the development of compact and low-loss opto-electronic oscillators (OEO), with applications in radar and wireless communications. However, current Si OEO have shown a limited performance. Si OEO relying on direct conversion of intensity modulated signals into the microwave domain yield a limited tunability. Wider tunability has been shown by indirect phase-modulation to intensity-modulation conversion, requiring precise control of the phase-modulation. Here, we propose a new approach enabling Si OEOs with wide tunability and direct intensity-modulation to microwave conversion. The microwave signal is created by the beating between an optical source and single sideband modulation signal, selected by an add-drop ring resonator working as an optical bandpass filter. The tunability is achieved by changing the wavelength spacing between the optical source and resonance peak of the resonator. Based on this concept, we experimentally demonstrate microwave signal generation between 6 GHz and 18 GHz, the widest range for a Si-based OEO. Moreover, preliminary results indicate that the proposed Si OEO provides precise refractive index monitoring, with a sensitivity of 94350 GHz RIU and a potential limit of detection of only 10-8 RIU, opening a new route for the implementation of high-performance Si photonic sensors

A Decade of Implantation of the Bachelor’s Degree in Electrical Engineering in the Western Amazon

This paper deals with the implementation of the Bachelor\u27s Degree in Electrical Engineering in Western Amazonia, as well as it presents an analysis of the academic performance of students in the Basic and Professional Core. The Federal University of Rondônia Foundation (UNIR), located in Porto Velho, Brazil, started the activities of the course in 2007 and continues to invest in the infrastructure and qualification of human resources in order to stimulate technological development in the region. Analyzing the performance data of the academics regarding the degree of difficulty established from the curricular offer, it is possible to infer some answers. In the course of the analysis, the databases emerged by taking note, such as students who only enroll and do not attend the course, among others. The disciplines diverged into two segments, Basic Core (NB) and Professional Core (NP). The data refers to the grades obtained by the students in all the disciplines studied and offered by the Academic Electrical Engineering Department (DAEE) in the period from 2007/1 to 2016/2. Along the analysis, two graphs demonstrated the evaluation. The analysis of the academic performance of students in the subjects during the NB and NP reinforces the result obtained in the Program for International Student Assessment (PISA), since Brazil has not obtained progress in science, reading, and mathematics averages. The results obtained indicate the necessity of effective measures in primary and secondary education since the deficit propagated to superior levels