392 research outputs found
A possibility of existence of a pseudovector-type quark-antiquark condensate in the quark matter and Nambu-Goldstone modes on that condensate in the Nambu-Jona-Lasinio model
A possibility of a pseudovector-type quark-antiquark condensed phase, which
leads to a quark spin polarized phase, in the quark matter is investigated
taking account of the vacuum effects leading to the chiral symmetry breaking by
using the Nambu-Jona-Lasinio model. Also, possible Nambu-Goldstone modes on the
pseudovector-type quark-antiquark condensate and the tensor-type
quark-antiquark condensate, which also leads to the quark spin polarized phase,
are investigated.Comment: 28 pages, 3 figure
Development of symptoms in arachnoid cysts
Arachnoid cysts are benign developmental anomalies of the central nervous system and arise in virtually all locations where arachnoid membrane exists. It is reported that they account for approximately 1% of all intracranial lesions and are caused by the splitting of the arachnoid membrane. Many authors have indicated that arachnoid cysts typically remain constant in size or grow very slowly. Therefore, most opportunities to detect arachnoid cysts are incidental. However, recent advent of more advanced imaging techniques has increased the frequencies to find them. The enlargement of arachnoid cysts are reported to occur most frequently in patients under 5 years of age, and the symptoms and signs derived from arachnoid cysts include elevated intracranial hypertension and focal signs due to the effects of compression to the surrounding cerebral parenchyma. Even in cases in which neurological symptoms are present, it is often difficult to properly correlate nonspecific signs and symptoms with the findings of arachnoid cysts. This is especially true in the cases common symptoms, such as headache, that arise frequently in the general population. In most of the cases, arachnoid cysts usually bring with a thin and bulging inner table of the skull. These bone deformities suggest a long process accompanying a gradual increase in intracystic pressure that probably begins in early infancy. Three mechanisms of the cyst expansion in arachnoid cysts have been described by many authors as follows: First, osmotic gradient between the cyst and the surrounding subarachnoid space induced fluid influx into the cyst cavity; second, fluid is secreted from ependymal cells on the cyst wall; third, a one-way ball-valve mechanism develops on the cyst wall. Almost symptomatic arachnoid cysts belong in children, the progressive growth of the skull and plasticity of the brain in children can buffer the mass effect caused by the cysts. Therefore, the arachnoid cysts in children and adolescence are usually asymptomatic or minimally symptomatic. The patient’s symptoms develop once the breakdown of compensatory mechanism in the brain surrounding the arachnoid cyst happens. Even in elderly patients with or without cyst expansion, the breakdown of compensatory mechanisms can lead to relatively rapid progression of symptoms. However, the factors that induce the breakdown of compensatory capacity remain unknown. In addition to those mechanisms, the symptomatic arachnoid cyst infrequently associates with intracranial hematoma, such as chronic subdural hematoma, acute subdural hematoma, acute epidural hematoma, and intra-cyst wall hematoma. Especially, it is well known that arachnoid cysts located in the middle cranial fossa can present with chronic subdural hematoma. The hematomas are frequently induced by minor trauma. The symptoms in arachnoid cysts are presented according to the various locations arachnoid cysts arise, and the developmental mechanisms are also discussed with the aspects of accompanying hydrocephalus or intracranial hematomas, and patients’ ages. © 2016 by Nova Science Publishers, Inc. All rights reserved.Embargo Period 12 months[Book Chapter
Vascular anatomy of the sellar region and complications during endoscopic endonasal transsphenoidal surgery for pituitary adenomas
In general, transsphenoidal surgery has been considered to have a low rate of complication and mortality. Among the postoperative complications associated with transsphenoidal surgery (TSS), such as cerebrospinal fluid leakage, hypopituitarism, diabetes insipidus, vascular injury, meningitis, cranial nerve neuropathy, and nasal bleeding, vascular injury is unusual, but most possibly fatal complication. Therefore, the pituitary neurosurgeons need to have the knowledge about the possible incidence during the intra-and post-operative phase. Vascular injuries during the TSS described in the literature include fatal hemorrhage from internal carotid artery (ICA), ICA occlusion, pseudoaneurysm formation, carotid cavernous fistula, subarachnoid hemorrhage, vasospasm, and distal embolism with cerebral infarction. It is important to understand the patient’s vascular anatomy at the sella and its surrounding structures, during the preoperative examination of the TSS, to avoid the vascular complications. Although recent advancement of the operative techniques and instruments of transsphenoidal approach enable the neurosurgeons to dissect arteries derived from the ICA and external carotid artery (ECA) during the surgery, it remains a difficult problem to preserve intact vessels even for the expert pituitary neurosurgeons. In particular, the introduction of endoscope into the TSS dramatically improved intraoperative visualization and diminished traumatization. Subsequently, the operative indication for performing TSS gradually developed to include the suprasellar, parasellar, clival, and cervicomedullary junction (extended transsphenoidal surgery). However, since the indications for the use of TSS have grown, this fact can lead to increasing chances of intraoperative vascular injuries, and till now has not been reached a definite conclusion, whether TSS has a significant difference in the complication rate between endoscope and microscope techniques. Another advancement of preoperative neuroradiological investigation to detect such arteries derived from the ICA and the ECA is also useful for their precise localization and avoidance of fatal complications. Especially, the role of digital subtraction angiography in the operating room is significant, because, once the arterial injury during TSS happens, the emergent detection of affected vessel(s) and the management of the trauma is required. In addition, the development of endovascular surgery both in the techniques and the instruments remarkably changed the principles of treatment for intraoperative vascular injury during the TSS. Especially, in cases of ICA injury, the endovascular treatment with parent artery occlusion can be performed with acceptable morbidity and mortality rates. This technique can be also applied to the pseudoaneurysm, which arises from the injury site of the ICA at the postoperative delayed period, and causes fatal and massive epistaxis. However, vascular injury during endoscopic endonasal TSS is not well studied or reported, despite it is still a feared complication. The anatomic substrate for such complication in each stage of the TSS (naso-sphenoidal, spheno-planum, dural, intrasellar, and suprasellar phase) is discussed with respect to operative and neuroradiological aspects, identification of risk factors, management strategies for avoidance of such serious vascular complications, and their outcomes. © 2016 by Nova Science Publishers, Inc. All rights reserved.[Book Chapter]Embargo Period 12 month
Rapid Growth of Dense and Long Carbon Nanotube Arrays and Its Application in Spinning Thread
Carbon nanotubes (CNTs), a dependable allotrope of carbon, are foreseen to lead technology further to its reach. Also, the most researched carbon allotrope in its form. Drawable CNTs have recently unraveled numerous possible applications utilizing vertically aligned CNTs also termed as “CNT forest.” In recent years, the rapid growth of dense and long carbon nanotube arrays has succeeded in surpassing its challenges by synthesizing dense and long CNT arrays. Length, density, and drawability tuning in the synthesis of CNT arrays have always been a complex issue lately. However, numerous research techniques emerged focusing on length and density control. Hence, this book chapter aids in unveiling the current achievements in the growth of dense and long CNT arrays and their application in spinning threads or CNT yarns with numerous other possible applications
Whitish daytime radiative cooling using diffuse reflection of non-resonant silica nanoshells
Daytime radiative cooling offers efficient passive cooling of objects by tailoring their spectral responses, holding great promise for green photonics applications. A specular reflector has been utilized in cooling devices to minimize sunlight absorption, but such a glaring surface is visually less appealing, thus undesirable for public use. Here, by exploiting strong diffuse reflection of silica nanoshells in a polymer matrix, daytime radiative cooling below the ambient temperature is experimentally demonstrated, while showing whitish color under sunlight. The cooling device consists of a poly(methyl methacrylate) layer with randomly distributed silica nanoshells and a polydimethylsiloxane (PDMS) layer on an Ag mirror. The non-resonant nanoshells exhibit uniform diffuse reflection over the solar spectrum, while fully transparent for a selective thermal radiation from the underneath PDMS layer. In the temperature measurement under the sunlight irradiation, the device shows 2.3 degrees C cooler than the ambient, which is comparable to or even better than the conventional device without the nanoshells. Our approach provides a simple yet powerful nanophotonic structure for realizing a scalable and practical daytime radiative cooling device without a glaring reflective surface
血液脳関門における新しい薬剤通過機構の開発
金沢大学医薬保健研究域医学系研究課題/領域番号:15790763, 研究期間(年度):2003出典:「血液脳関門における新しい薬剤通過機構の開発」研究成果報告書 課題番号15790763(KAKEN:科学研究費助成事業データベース(国立情報学研究所))(https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-15790763/)を加工して作
Enrichment of Spermatogonial Stem Cells using Side Population in Teleost
Spermatogenesis originates from a small population of spermatogonial stem cells; this population can maintain continuous sperm production throughout the life of fish via self-renewal and differentiation. Despite their biological importance, spermatogonial stem cells are not thoroughly characterized because they are difficult to distinguish from their progeny 5 cells that become committed to differentiation. We previously established a novel technique for germ cell transplantation to identify spermatogonial stem cells based on their colonizing activity and their ability to initiate donor-derived gametogenesis in the rainbow trout (Oncorhynchus mykiss). Although spermatogonial stem cells can be retrospectively identified after transplantation, there is currently no technique to prospectively enrich for or purify spermatogonial stem cells. Here, we describe a method for spermatogonial stem-cell enrichment using side-population. With optimized Hoechst 33342 staining conditions, we successfully identified side-population cells among type A spermatogonia. Side-population cells were transcriptomically and morphologically distinct from non-side-population cells. To functionally determine whether the transplantable spermatogonial stem cells were enriched in the side-population fraction, we compared the colonization activity of side-population cells with that of non-side-population cells. Colonization efficiency was significantly higher with side-population cells than with non-side-population cells or with total type A spermatogonia. In addition, side-population cells could produce billions of sperm in recipient. These results indicated that transplantable spermatogonial stem cells were enriched in the side-population fraction. This method will provide biological information that may advance our understanding of spermatogonial stem 20 cells in teleosts. Additionally, this technique will increase the efficiency of germ-cell transplantation used in surrogate broodstock technology
Gata6 Promotes GLI3 Repressor Activities in the Limb
Gli3 is a major regulator of Hedgehog signaling during limb development. In the anterior mesenchyme, GLI3 is proteolytically processed into GLI3R, a truncated repressor form that inhibits Hedgehog signaling. Although numerous studies have identified mechanisms that regulate Gli3 function in vitro, it is not completely understood how Gli3 function is regulated in vivo. In this study, we show a novel mechanism of regulation of GLI3R activities in limb buds by Gata6, a member of the GATA transcription factor family. We show that conditional inactivation of Gata6 prior to limb outgrowth by the Tcre deleter causes preaxial polydactyly, the formation of an anterior extra digit, in hindlimbs. A recent study suggested that Gata6 represses Shh transcription in hindlimb buds. However, we found that ectopic Hedgehog signaling precedes ectopic Shh expression. In conjunction, we observed Gata6 and Gli3 genetically interact, and compound heterozygous mutants develop preaxial polydactyly without ectopic Shh expression, indicating an additional prior mechanism to prevent polydactyly. These results support the idea that Gata6 possesses dual roles during limb development: enhancement of Gli3 repressor function to repress Hedgehog signaling in the anterior limb bud, and negative regulation of Shh expression. Our in vitro and in vivo studies identified that GATA6 physically interacts with GLI3R to facilitate nuclear localization of GLI3R and repressor activities of GLI3R. Both the genetic and biochemical data elucidates a novel mechanism by Gata6 to regulate GLI3R activities in the anterior limb progenitor cells to prevent polydactyly and attain proper development of the mammalian autopod
Synthesis of solvent-free conductive and flexible cellulose-carbon nanohorn sheets and their application as a water vapor sensor
Carbon nanohorns (CNHs) are mixed with cellulose to make freestanding thin-film conductive sheets. CNHs, at different ratios (5, 10, 25, 50 wt%), form composites with cellulose (hydroxyethylcellulose). Freestanding cellulose-carbon nanohorn (CCN) sheets were fabricated using a 100 mu m-thick metal bar coater. Surfactants or any other chemical treatments to tailor the surface properties of CNHs were avoided to obtain composite sheets from pristine CNHs and cellulose. Utilizing the hygroscopic property of hydroxyethylcellulose and the electrical conductivity of CNHs paved a path to perform this experiment. The synthesis technique is simple, and the fabrication and drying of the sheets were effortless. As the loading concentration of CNH increased, the resistance, flexibility, and strength of the CCN composite sheets decreased. The maximum loading concentration possible to obtain a freestanding CCN sheet is 50 wt%. The resistance of the maximum loading concentration of CNH was 53 k omega. The response of the CCN sheets to water vapor was 4 s and recover time was 13 s, and it is feasible to obtain a response for different concentrations of water vapor. High-resolution transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, resistance measurement, tensile strength measurement, and thermogravimetric analysis were used to investigate the mechanical, morphological, electrical, and chemical properties of the CCN sheets
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