544 research outputs found
Polycystic ovary syndrome
Thedescription of polycystic ovaries dates back as far as 17211 but it was Stein and Leventhal who first reported the disorder, that we now know as the polycystic ovary (or ovarian) syndrome (PCOS), in seven women with amenorrhoea, enlarged ovaries with multiple cysts and hirsutism.2 These patients were treated with ovarian wedge resection and of the seven all had return of their menstrual cycles, and two conceived. With the advent of hormonal assays in the late 1960’s and early 1970’s, the diagnostic focus expanded to include endocrine abnormalities in the hypothalamic-pituitary-gonadal (HPG) axis.3 Elevated luteinising hormone (LH) levels and hyperandrogenaemia were therefore added to the diagnostic criteria for PCOS.4 The advent of pelvic ultrasonography in the late 1970’s allowed for the non-invasive detection of polycystic ovarian morphology. However, this tool confounded matters when it was discovered that polycystic ovaries was a “common finding in normal women”,5 and that it also occurred in diverse endocrine disorders such as hypothyroidism, hyperprolactinaemia, congenital adrenal hyperplasia and hypothalamic amenorrhoea.6 The finding of polycystic ovaries in normal women has been variably referred to as polycystic ovarian disease (PCOD), polycystic ovaries (PCO) and polycystic ovarian morphology (PCOM). We prefer the to use the term PCOM in this setting as it simply describes the ultrasound appearance of the ovaries without any syndromic connotations. Despite the strong link between diabetes mellitus and PCOS, it was only in 1980 when Burghen and coworkers first described hyperinsulinaemia and insulin resistance in PCOS.7 This has subsequently been confirmed by many others. The identification of PCOS now encompasses a heterogeneous presentation but has at its core three principal features:i. Hyperandrogenismii. Anovulation, and/oriii. Polycystic ovarian morphology (PCOM) on ultrasonography Keywords: polycystic ovary syndrome, PCOS, polycystic ovarian disease, PCOD, polycystic ovarian morphology, PCO
MICRO‐TEXTURED BORON NITRIDE NANOPLATELET MODIFIED POLYETHYLENE FILMS
Linear low density polyethylene (LLDPE) micro‐textured films filled with boron nitride nanoplatelets (BNN) were produced by continuous melt extrusion. Nanoparticles displayed a significant extent of dispersion inside the matrix. The addition of BNN led to more than 10‐fold increase of the in‐plane thermal conductivity (TC) of the nanocomposite (7.7 W/m.K vs 0.3 W/m.K for pure LLDPE), and 1.3‐fold increase of through thickness TC. To increase the surface area available for convective heat transfer, micro‐textured films (T‐BNN) were produced from a micro‐patterned die. Nanoplatelets were aligned parallel to the film machine direction. Film stiffness and tensile strength are comparable to the base LLDPE. Textures and BNN lubricant property helped to decrease the coefficientof friction
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Processing of Carbon Fiber Reinforced Composites by Three Dimensional Photolithography
The reinforcement of photoresins with continuous carbon fibers is discussed in this
paper. The processing was conducted in an automated desktop photolithography unit
(ADPU) developed and built in-house. Continuous fibers were added in situ to the
photoresin to obtain composite samples containing over 20 vol% of the fibers. The tensile
strength of these composites improved by at least a factor of 2 as compared to that of the
pure photoresins. It is also noted that the photoresin could be partially cured to develop
sufficient green strength in the composite samples even though the fibers are opaque to
ultraviolet radiation. These results indicate the potential of this technique to produce
functional composite components in conjunction with a 3-D photolithography apparatus.Mechanical Engineerin
CEFUROXIME-INDUCED THROMBOCYTOPENIA: IT'S JUST NOT IN THE RING??
Beta lactams are one of the most commonly used antibiotic groups in clinical practice, owing to their relatively superior safety profile, when weighed against other available antibiotics. Cephalosporins have overgrown over the years, now extending across five generations of drugs. Older cephalosporins are still commonly used, chiefly because of their low cost and minimal adverse effects. However, no drug is entirely free of adverse effects. Cephalosporins (especially those with a methylthiotetrazole ring) have been associated with bleeding manifestations due to hypoprothrombinemia and thrombocytopenia in susceptible subsets of the global population. This case report concerns the use of a cephalosporin that does not have this ring in its structure, but has still caused a rare instance of thrombocytopeniaKeywords: Beta lactam, Cefuroxime, Platelets, Bleeding, Methylthiotetrazole
Surface Anchoring of Nematic Phase on Carbon Nanotubes: Nanostructure of Ultra-High Temperature Materials
Nuclear energy is a dependable and economical source of electricity. Because fuel supply sources are available domestically, nuclear energy can be a strong domestic industry that can reduce dependence on foreign energy sources. Commercial nuclear power plants have extensive security measures to protect the facility from intruders [1]. However, additional research efforts are needed to increase the inherent process safety of nuclear energy plants to protect the public in the event of a reactor malfunction. The next generation nuclear plant (NGNP) is envisioned to utilize a very high temperature reactor (VHTR) design with an operating temperature of 650-1000ðC [2]. One of the most important safety design requirements for this reactor is that it must be inherently safe, i.e., the reactor must shut down safely in the event that the coolant flow is interrupted [2]. This next-generation Gen IV reactor must operate in an inherently safe mode where the off-normal temperatures may reach 1500ðC due to coolant-flow interruption. Metallic alloys used currently in reactor internals will melt at such temperatures. Structural materials that will not melt at such ultra-high temperatures are carbon/graphtic fibers and carbon-matrix composites. Graphite does not have a measurable melting point; it is known to sublime starting about 3300ðC. However, neutron radiation-damage effects on carbon fibers are poorly understood. Therefore, the goal of this project is to obtain a fundamental understanding of the role of nanotexture on the properties of resulting carbon fibers and their neutron-damage characteristics. Although polygranular graphite has been used in nuclear environment for almost fifty years, it is not suitable for structural applications because it do not possess adequate strength, stiffness, or toughness that is required of structural components such as reaction control-rods, upper plenum shroud, and lower core-support plate [2,3]. For structural purposes, composites consisting of strong carbon fibers embedded in a carbon matrix are needed. Such carbon/carbon (C/C) composites have been used in aerospace industry to produce missile nose cones, space shuttle leading edge, and aircraft brake-pads. However, radiation-tolerance of such materials is not adequately known because only limited radiation studies have been performed on C/C composites, which suggest that pitch-based carbon fibers have better dimensional stability than that of polyacrylonitrile (PAN) based fibers [4]. The thermodynamically-stable state of graphitic crystalline packing of carbon atoms derived from mesophase pitch leads to a greater stability during neutron irradiation [5]. The specific objectives of this project were: (i) to generating novel carbonaceous nanostructures, (ii) measure extent of graphitic crystallinity and the extent of anisotropy, and (iii) collaborate with the Carbon Materials group at Oak Ridge National Lab to have neutron irradiation studies and post-irradiation examinations conducted on the carbon fibers produced in this research project
MRBrainS Challenge: Online Evaluation Framework for Brain Image Segmentation in 3T MRI Scans
Many methods have been proposed for tissue segmentation in brain MRI scans. The multitude of methods proposed complicates the choice of one method above others. We have therefore established the MRBrainS online evaluation framework for evaluating (semi) automatic algorithms that segment gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) on 3T brain MRI scans of elderly subjects (65-80 y). Participants apply their algorithms to the provided data, after which their results are evaluated and ranked. Full manual segmentations of GM, WM, and CSF are available for all scans and used as the reference standard. Five datasets are provided for training and fifteen for testing. The evaluated methods are ranked based on their overall performance to segment GM, WM, and CSF and evaluated using three evaluation metrics (Dice, H95, and AVD) and the results are published on the MRBrainS13 website. We present the results of eleven segmentation algorithms that participated in the MRBrainS13 challenge workshop at MICCAI, where the framework was launched, and three commonly used freeware packages: FreeSurfer, FSL, and SPM. The MRBrainS evaluation framework provides an objective and direct comparison of all evaluated algorithms and can aid in selecting the best performing method for the segmentation goal at hand.This study was financially supported by IMDI Grant 104002002 (Brainbox) from ZonMw, the Netherlands Organisation for Health Research and Development, within kind sponsoring by Philips, the University Medical Center Utrecht, and Eindhoven University of Technology. The authors would like to acknowledge the following members of the Utrecht Vascular Cognitive Impairment Study Group who were not included as coauthors of this paper but were involved in the recruitment of study participants and MRI acquisition at the UMC Utrecht (in alphabetical order by department): E. van den Berg, M. Brundel, S. Heringa, and L. J. Kappelle of the Department of Neurology, P. R. Luijten and W. P. Th. M. Mali of the Department of Radiology, and A. Algra and G. E. H. M. Rutten of the Julius Center for Health Sciences and Primary Care. The research of Geert Jan Biessels and the VCI group was financially supported by VIDI Grant 91711384 from ZonMw and by Grant 2010T073 of the Netherlands Heart Foundation. The research of Jeroen de Bresser is financially supported by a research talent fellowship of the University Medical Center Utrecht (Netherlands). The research of Annegreet van Opbroek and Marleen de Bruijne is financially supported by a research grant from NWO (the Netherlands Organisation for Scientific Research). The authors would like to acknowledge MeVis Medical Solutions AG (Bremen, Germany) for providing MeVisLab. Duygu Sarikaya and Liang Zhao acknowledge their Advisor Professor Jason Corso for his guidance. Duygu Sarikaya is supported by NIH 1 R21CA160825-01 and Liang Zhao is partially supported by the China Scholarship Council (CSC).info:eu-repo/semantics/publishedVersio
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