107 research outputs found
Revisiting the pre-main-sequence evolution of stars I. Importance of accretion efficiency and deuterium abundance
Recent theoretical work has shown that the pre-main-sequence (PMS) evolution
of stars is much more complex than previously envisioned. Instead of the
traditional steady, one-dimensional solution, accretion may be episodic and not
necessarily symmetrical, thereby affecting the energy deposited inside the star
and its interior structure. Given this new framework, we want to understand
what controls the evolution of accreting stars. We use the MESA stellar
evolution code with various sets of conditions. In particular, we account for
the (unknown) efficiency of accretion in burying gravitational energy into the
protostar through a parameter, , and we vary the amount of deuterium
present. We confirm the findings of previous works that the evolution changes
significantly with the amount of energy that is lost during accretion. We find
that deuterium burning also regulates the PMS evolution. In the low-entropy
accretion scenario, the evolutionary tracks in the H-R diagram are
significantly different from the classical tracks and are sensitive to the
deuterium content. A comparison of theoretical evolutionary tracks and
observations allows us to exclude some cold accretion models () with
low deuterium abundances. We confirm that the luminosity spread seen in
clusters can be explained by models with a somewhat inefficient injection of
accretion heat. The resulting evolutionary tracks then become sensitive to the
accretion heat efficiency, initial core entropy, and deuterium content. In this
context, we predict that clusters with a higher D/H ratio should have less
scatter in luminosity than clusters with a smaller D/H. Future work on this
issue should include radiation-hydrodynamic simulations to determine the
efficiency of accretion heating and further observations to investigate the
deuterium content in star-forming regions. (abbrev.)Comment: Published in A&A. 16 pages, 14 figure
Revisiting the pre-main-sequence evolution of stars II. Consequences of planet formation on stellar surface composition
We want to investigate how planet formation is imprinted on stellar surface
composition using up-to-date stellar evolution models. We simulate the
evolution of pre-main-sequence stars as a function of the efficiency of heat
injection during accretion, the deuterium mass fraction, and the stellar mass.
For simplicity, we assume that planet formation leads to the late accretion of
zero-metallicity gas, diluting the surface stellar composition as a function of
the mass of the stellar outer convective zone. We adopt
as an
uncertain but plausible estimate of the mass of heavy elements that is not
accreted by stars with giant planets, including our Sun. By combining our
stellar evolution models to these estimates, we evaluate the consequences of
planet formation on stellar surface composition. We show that after the first
Myr, the evolution of the convective zone follows classical
evolutionary tracks within a factor of two in age. We find that planet
formation should lead to a scatter in stellar surface composition that is
larger for high-mass stars than for low-mass stars. We predict a spread in
[Fe/H] of approximately dex for stars with K,
marginally compatible with differences in metallicities observed in some binary
stars with planets. Stars with K may show much
larger [Fe/H] deficits, by 0.6 dex or more, compatible with the existence of
refractory-poor Boo stars. We also find that planet formation may
explain the lack of refractory elements seen in the Sun as compared to solar
twins, but only if the ice-to-rock ratio in the solar-system planets is less
than and planet formation began less than Myr after
the beginning of the formation of the Sun. (abbreviated)Comment: Accepted for publicatoin in A&A. 18 pages, 14 figure
Pseudosarcomatous Proliferation of Cx43- and Kit-Expressing Interstitial Cell in the Urinary Bladder
The authors report a case showing proliferation of KIT- and connexin 43-expressing mesenchymal cells of the urinary bladder. A 75-year-old woman had an ulcerated endophytic mass (size, approximately 2 × 2 cm) in the left posterolateral wall. She underwent transurethral resection and subsequent partial cystectomy. The suburothelial mass extended to the muscularis propria. The histopathological analysis revealed spindle-shaped mesenchymal cells that were loosely arranged with myxoid stroma and showed a focal compact fascicular arrangement. In the immunohistochemical analysis, these spindle cells were stained with specific antibodies to KIT and connexin 43. The patient is currently free of disease at 5 years after operation. The proliferating spindle cells in the present case might represent a phenotype of interstitial cells of the lamina propria
Advanced Dry Gas Seal By The Dynamic Ion Beam Mixing Technique.
LecturePg. 39-48Ductile materials have been used for dry gas seal mating rings to
replace conventional sintered materials that have experienced
occasional brittle fracture. The ductile materials require a coating
to make them suitable for dry gas seal designs.
This paper describes the dynamic ion beam mixing (DM)
technique as an improvement in coating technology. Excellent
tribological properties of thin titanium nitride (TiN) films formed
by the dynamic ion beam mixing technique (DM/TiN) are
demonstrated. Further, performance of a dry gas seal provided with
a mating ring comprising a martensitic stainless steel substrate,
having a DM/TiN coating formed thereon, is demonstrated, while
making a comparison with the performance of a dry gas seal
utilizing conventional materials. Considerations necessary for
designing the ductile mating ring, its durability under abnormal
and severe conditions, testing of the DM coating, and results of
field experience are also discussed, together with problems
accompanying the use of ductile materials
Immunohistochemistry or Molecular Analysis : Which Method Is Better for Subtyping Craniopharyngioma?
Craniopharyngioma (CP) is mainly classified into two pathological subtypes: adamantinomatous (ACP) and papillary (PCP). CTNNB1 (β-catenin) mutations are detected in ACPs, and the BRAF V600E mutation is detected in PCPs. However, genetic analysis is not always possible in general medical practice. In this study, we investigated whether immunohistochemistry could replace genetic analysis as an aid in subtype diagnosis. Here, 38 CP patients who had undergone their first tumor resection were included. Among the 38 cases, 22 were morphologically diagnosed as ACP, 10 cases were diagnosed as PCP, and six cases were diagnosed as undetermined CP that were morphologically difficult to classify as either ACP or PCP. Results of immunohistochemistry and genetic analysis and clinical features were compared. Based on the immunohistochemistry, 26 (22 ACPs and four undetermined CPs) showed nuclear β-catenin expression, 11 (nine PCPs and two undetermined CPs) exhibited positive BRAF V600E immunostaining and one PCP showed membranous β-catenin expression and negative for BRAF V600E immunostaining. Among the 26 nuclear β-catenin expression cases, 11 had CTNNB1 mutations; however, 15 cases had mutations of neither CTNNB1 nor BRAF V600E. All 11 BRAF V600E immunopositive cases had BRAF V600E mutations. When comparing clinical features between, pediatric patients and those with tumor calcification and less solid components on MRI more commonly had nuclear β-catenin expression tumors than BRAF V600E immunopositive tumors, reflecting the differences in clinical features between ACP and PCP. Accordingly, immunohistochemistry can replace genetic analysis as an aid to determine the subtype diagnosis of CP in general medical practice
Tonic GABAergic Inhibition Is Essential for Nerve Injury-Induced Afferent Remodeling in the Somatosensory Thalamus and Ectopic Sensations
Estudos sorológicos e parasitologies na Amebíase e em outras infecções parasitárias intestinais em Recife e áreas circunvizinhas, nordeste do Brasil
Parasitological examinations were carried out during April to August, 1987, with 187 out-patients of the IMIP hospital, located in the center of Recife City, and 464 inhabitants of several villages around Cabo City, 50 Km southeast of Recife, Pernambuco, Brazil. Approximately 71% of the IMIP patients and 92% of the Cabo inhabitants were infected with at least one species of intestinal parasite. There was minimum difference in the prevalence rate of Trichuris trichiura between two areas, whereas the prevalence rates of Ascaris lumbricoides, hookworms, Strongyloides stercoralis, Schistosoma mansoni and Entamoeba histolytica were higher in the inhabitants of the Cabo City area. Only Giardia lamblia was more prevalent in the out-patients of IMIP hospital. Test tube cultivation revealed that the prevalence rate of Necator americanus in both areas was much higher than that of Ancylostoma duodenale , and also that the prevalence rate of S. stercoralis of the IMIP patients and Cabo inhabitants were 4.5% and 9.6%, respectively. Six hundred and fifteen sera were serologically examined for amoebiasis by the gel diffusion precipitation test (GDP) and enzyme linked immunosorbent assay (ELISA) using the antigen prepared from axenically cultured trophozoite of E. histolytica (strain HM-ITMSS). No positive reaction was observed in all of the sera as examined by GDP, while 32 out of 615 sera were positive on ELISA.Exames parasitológies foram realizados em 187 pacientes do Hospital do IMIP e 464 habitantes de vários vilarejos no município do Cabo, 50 Km à sudeste de Recife, durante os meses de abril a agosto. Aproximadamente 71% dos pacientes examinados do IMIP e 92% dos examinados do Cabo apresentavam-se infectados com, no mínimo, uma espécie de parasita intestinal. Houve uma diferença mínima na taxa de prevalência de Trichuris trichiura entre as duas áreas, entretanto a prevalência de Ascaris lumbricoides, família Ancylostomidae, Strongyloides stercoralis, Schistosoma mansoni e Entamoeba histolytica foi maior entre os habitantes do Cabo. Somente a Giardia lamblia apresentou uma taxa de prevalência maior nos pacientes do IMIP. O cultivo em tubo de ensaio revelou que a prevalência do Necator americanus em relação a do Ancylostoma duodenale era muito maior em ambas as áreas e que a do S. stercoralis entre os pacientes do IMIP e dos habitantes do Cabo era, respectivamente, 4.5% e 9.6%. A amebíase foi verificada através de exames sorológicos, imunodifusão em gel (GDP) e enzima imunoensaio (ELISA), usando como antígeno extrato bruto preparado a partir dos trofozoitos de E. histolytica (cepa HM-1: IMSS), realizados em 615 soros, onde nenhuma reação positiva aparente foi observada através da imunodifusão, contudo foram observados resultados positivos em 32 dos 615 casos através da enzima imunoensaio
Parasitological and serological studies on amoebiasis and other intestinal parasitic infections in the rural sector around Recife, Northeast Brazil
自己の捉え方の関連要因に関する研究
【目的】本研究は,健康な生活を確立するための様々なライフスタイル要因のうち,特に自己の捉え方に関連する要因を検討することを目的とした.【方法】北海道医療大学2005年度新入学生(570名)を調査対象とし,調査当日の講義出席者に対し回答を求めた.回収した質問紙票を基にOKグラムを分類し,自己の捉え方を目的変数として健康生活習慣,ソーシャル・サポート,自覚症状とのクロス表を作成し,関連の有意性を検討した.【結果】健康生活習慣の「趣味の有無」「悩みの有無」,「ソーシャル・サポートの有無」に有意な関連が認められ,それぞれの項目について好ましい回答群の方が自己肯定群の相対的出現率が上がる傾向がみられた.【考察】これらの結果から,「趣味があり,悩みが無く,ソーシャル・サポートがある」という方が自己肯定的な構えを持つ傾向が示唆された.Purpose : This study was aimed at examining a factor to be related to a posture of self in particular among various lifestyle factors to establish healthy life. Method : An investigation object is fresh students in 2005 of Health Science University of Hokkaido(570). For the students that it attends during a lecture of the investigation day to have demanded an answer. We classified OK grams based on the questionnaire which collected. We examined related significance with various lifestyle factors as a purpose variable by posture of self. Results : As a result of analysis, the item where there was significant relation in posture of self was "presence of a hobby" and "presence of a trouble" of a healthy habit, it and "presence of social support". The tendency that was high relative incidence of "affirmative self was recognized "favorable answer group" in comparison with "unfavorable answer group", in those items. Consideration : From these results, a tendency that "the person whom there was a hobby, and there was not a trouble, and had social support" was affirmative by oneself was suggested
Second nationwide surveillance of bacterial pathogens in patients with acute uncomplicated cystitis conducted by Japanese Surveillance Committee from 2015 to 2016: antimicrobial susceptibility of Escherichia coli, Klebsiella pneumoniae, and Staphylococcus saprophyticus
The Japanese Surveillance Committee conducted a second nationwide surveillance of antimicrobial susceptibility patterns of uropathogens responsible for acute uncomplicated cystitis (AUC) in premenopausal patients aged 16–40 years old at 31 hospitals throughout Japan from March 2015 to February 2016. In this study, the susceptibility of causative bacteria (Escherichia coli, Klebsiella pneumoniae, Staphylococcus saprophyticus) for various antimicrobial agents was investigated by isolation and culturing of organisms obtained from urine samples. In total, 324 strains were isolated from 361 patients, including E. coli (n = 220, 67.9%), S. saprophyticus (n = 36, 11.1%), and K. pneumoniae (n = 7, 2.2%). The minimum inhibitory concentrations (MICs) of 20 antibacterial agents for these strains were determined according to the Clinical and Laboratory Standards Institute (CLSI) manual. At least 93% of the E. coli isolates showed susceptibility to fluoroquinolones and cephalosporins, whereas 100% of the S. saprophyticus isolates showed susceptibility to fluoroquinolones and aminoglycosides. The proportions of fluoroquinolone-resistant and extended-spectrum β-lactamase (ESBL)-producing E. coli strains were 6.4% (13/220) and 4.1% (9/220), respectively. The antimicrobial susceptibility of K. pneumoniae was retained during the surveillance period, while no multidrug-resistant strains were identified.
In summary, antimicrobial susceptibility results of our second nationwide surveillance did not differ significantly from those of the first surveillance. Especially the numbers of fluoroquinolone-resistant and ESBL-producing E. coli strains were not increased in premenopausal patients with AUC in Japan
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