283 research outputs found
An Unexpectedly Swift Rise in the Gamma-ray Burst Rate
The association of long gamma-ray bursts with supernovae naturally suggests
that the cosmic GRB rate should trace the star formation history. Finding
otherwise would provide important clues concerning these rare, curious
phenomena. Using a new estimate of Swift GRB energetics to construct a sample
of 36 luminous GRBs with redshifts in the range z=0-4, we find evidence of
enhanced evolution in the GRB rate, with ~4 times as many GRBs observed at z~4
than expected from star formation measurements. This direct and empirical
demonstration of needed additional evolution is a new result. It is consistent
with theoretical expectations from metallicity effects, but other causes remain
possible, and we consider them systematically.Comment: 4 pages, 4 figures; minor changes to agree with published versio
Pyramiding multiple genes for resistance to PVY, TSWV and PMMoV in pepper using molecular markers
Pepper (Capsicum annuum L.) is one of the most important vegetables cultivated worldwide. Many pests and pathogens cause economic yield losses in pepper. Potato virus Y (PVY), Tomato spotted wilt virus (TSWV) and Pepper mild mottle virus (PMMoV) are considered among the most destructive viruses affecting pepper in the world. Because chemical treatments have limited success for managing PVY, TSWV and PMMoV, resistant varieties are considered to be the most effective means of controlling these viruses. In this study, resistance genes to these viruses were successfully transferred to the superior sweet Charleston pepper line 'Y-CAR' using molecular markers and biological assays. As a result, a new line which is resistant to PVY, TSWV and PMMoV was developed. The results also showed the applicability of a pyramiding strategy for breeding multiple virus resistance in pepper. © Verlag Eugen Ulmer KG, Stuttgart.Scientific and Technological Research Council of Turkey, TEYDEP foundation (3080171
Učinak formulacijskih parametara na oslobađanje lijeka i svojstva dvoslojnih tableta koje plutaju u želucu
Floating dosage forms of acetylsalicylic acid, used for its antithrombotic effect, were developed to prolong gastric residence time and increase bioavailability. In the two-layer tablet formulation, hydroxypropyl methylcellulose (HPMC) of high viscosity and an effervescent mixture of citric acid and sodium bicarbonate formed the floating layer. The release layer contained the drug, direct tableting agent and different types of matrix-forming polymers such as HPMC of low viscosity, sodium carboxymethylcellulose and chitosan. Tablets were prepared using a direct compression technique. The effect of formulation variables on physicochemical and floating properties and the drug release from tablets were investigated. Floating ability was dependent on the amount of effervescent agent and gel-forming polymer of the floating layer. Drug release was prolonged to 8 hours by changing the type and viscosity of the matrix-forming polymer in the drug-loading layer and all formulations showed a diffusion release mechanism.U radu su opisane plutajuće tablete acetilsalicilne kiseline za antikoagulacijsku upotrebu s produljenim zadržavanjem u želucu i većom bioraspoloživošću. Plutajući dio tih dvoslojnih tableta sadržavao je hidroksipropil metilcelulozu (HPMC) visoke viskoznosti i efervescentnu smjesu limunske kiseline i natrijevog hidrogenkarbonata. Drugi sloj sadržavao je ljekovitu tvar, sredstvo za izravno tabletiranje i različite vrste matriksnog polimera poput HPMC niske viskoznosti, natrij-karboksimetilceluloze i kitozana. Tablete su pripravljene metodom izravne kompresije. Ispitivan je utjecaj formulacijskih varijabli na fizikokemijska i plutajuća svojstva, te oslobađanje ljekovite tvari. Plutajuća svojstva ovise o količini efervescentnih tvari i gelirajućeg polimera u plutajućem sloju. Promjenom vrste i viskoznosti polimera u matriksnom sloju s lijekom produljeno je oslobađanje ljekovite tvari na 8 sati. Iz svih formulacija ljekovita tvar oslobađala se difuzijom
Enhanced Cosmological GRB Rates and Implications for Cosmogenic Neutrinos
Gamma-ray bursts, which are among the most violent events in the universe,
are one of the few viable candidates to produce ultrahigh energy cosmic rays.
Recently, observations have revealed that GRBs generally originate from
metal-poor galaxies and do not directly trace cosmic star formation, as might
have been assumed from their association with core-collapse supernovae. Several
implications follow from these findings. The redshift distribution of observed
GRBs is expected to peak at higher redshift (compared to cosmic star
formation), which is supported by the mean redshift of the Swift GRB sample,
~3. If GRBs are, in fact, the source of the observed UHECR, then cosmic-ray
production would evolve with redshift in a stronger fashion than has been
previously suggested. This necessarily leads, through the GZK process, to an
enhancement in the flux of cosmogenic neutrinos, providing a near-term approach
for testing the gamma-ray burst-cosmic ray connection with ongoing and proposed
UHE neutrino experiments.Comment: 9 pages, 5 figures, references and two appendices added, conclusions
unchanged; accepted for publication in Phys.Rev.
Neutrino Mixing and Nucleosynthesis in Core-Collapse Supernovae
A simple description of core-collapse supernovae is given. Properties of the
neutrino-driven wind, neutrino fluxes and luminosities, reaction rates, and the
equilibrium electron fraction in supernova environments are discussed. Neutrino
mixing and neutrino interactions that are relevant to core-collapse supernovae
are briefly reviewed. The values of electron fraction under several evolution
scenarios that may impact rapid neutron capture process (r-process)
nucleosynthesis are calculated.Comment: 17 pages, 4 figure
Turner syndrome and associated problems in turkish children: A multicenter study
Objective: Turner syndrome (TS) is a chromosomal disorder caused by complete or partial X chromosome monosomy that manifests various clinical features depending on the karyotype and on the genetic background of affected girls. This study aimed to systematically investigate the key clinical features of TS in relationship to karyotype in a large pediatric Turkish patient population. Methods: Our retrospective study included 842 karyotype-proven TS patients aged 0-18 years who were evaluated in 35 different centers in Turkey in the years 2013-2014. Results: The most common karyotype was 45,X (50.7%), followed by 45,X/46,XX (10.8%), 46,X,i(Xq) (10.1%) and 45,X/46,X,i(Xq) (9.5%). Mean age at diagnosis was 10.2±4.4 years. The most common presenting complaints were short stature and delayed puberty. Among patients diagnosed before age one year, the ratio of karyotype 45,X was significantly higher than that of other karyotype groups. Cardiac defects (bicuspid aortic valve, coarctation of the aorta and aortic stenosi) were the most common congenital anomalies, occurring in 25% of the TS cases. This was followed by urinary system anomalies (horseshoe kidney, double collector duct system and renal rotation) detected in 16.3%. Hashimoto’s thyroiditis was found in 11.1% of patients, gastrointestinal abnormalities in 8.9%, ear nose and throat problems in 22.6%, dermatologic problems in 21.8% and osteoporosis in 15.3%. Learning difficulties and/or psychosocial problems were encountered in 39.1%. Insulin resistance and impaired fasting glucose were detected in 3.4% and 2.2%, respectively. Dyslipidemia prevalence was 11.4%. Conclusion: This comprehensive study systematically evaluated the largest group of karyotype-proven TS girls to date. The karyotype distribution, congenital anomaly and comorbidity profile closely parallel that from other countries and support the need for close medical surveillance of these complex patients throughout their lifespan. © Journal of Clinical Research in Pediatric Endocrinology
Novel TMC8 splice site mutation in epidermodysplasia verruciformis and review of HPV infections in patients with the disease
Epidermodysplasia verruciformis (EV) is a genodermatosis leading to infections with cutaneous HPV, persistent plane warts and a high rate of non-melanoma skin cancer (NMSC). Biallelic loss-of-function mutations in TMC6 and TMC8 are known to be causative.; The aim of this study was to report EV-causing mutations in four patients with EV and to give an overview of all described patients with EV.; We investigated four patients with classical features of EV from two families. All patients were affected by plane warts with typical EV histology since early childhood, and β-HPVs were detected on their skin. One patient had recurring cutaneous squamous cell carcinomas (cSCC) and carcinomas in situ (Bowen type). We sequenced both TMC6/8 for disease-causing mutations and quantified levels of gene expression. We also performed a systematic literature review to discuss these patients in the context of previously reported cases, mutations already identified, as well as HPV types.; Three patients of one family carried a homozygous splice site mutation in TMC8 resulting in aberrantly spliced transcripts that were not degraded. By contrast, no TMC6/8 mutation was detected in the patient from the other family. A systematic literature review revealed 501 described patients with EV. Around 40% of patients with EV analysed for genetic alterations carried no mutation in TMC6/8. While β-HPVs were identified in the majority of cases, α-HPVs were detected in several individuals.; The relatively high proportion of EV patients without mutation in TMC6/8 indicates the existence of EV-causing mutations in additional, presently unknown gene(s). However, a homozygous TMC8 splice site mutation in our patients resulted in aberrant transcripts which cannot retain the healthy phenotype. The literature review revealed that HPV-5 is the most commonly identified HPV in patients with EV, but HPV-3, HPV-14 and HPV-20 were unexpectedly identified more frequently than HPV-8
Gastric Juvenile Polyposis with High-Grade Dysplasia in Pachydermoperiostosis
Pachydermoperiostosis (PDP) is the primary form of hypertrophic osteoarthropathy. It is a very rare disease consisting of pachydermia, digital clubbing and radiologic periostosis. Various digestive symptoms in PDP are seen in 11–49% of patients and juvenile polyps may be found at gastric endoscopy. We report here the history of a patient with PDP who was referred for assessment of severe anemia. Endoscopy of the upper digestive tract showed multiple polyps of the stomach with two huge lesions exhibiting foci of high-grade dysplasia. This observation suggests that PDP can be considered as a precancerous condition of the stomach and systematic screening using endoscopy should be considered in these patients
Effects of hypodontia on craniofacial structures and mandibular growth pattern
Introduction
This study was performed to examine craniofacial structures in persons with hypodontia and to reveal any differences, that may occur, when agenetic teeth are only found in the maxilla, the mandible or in both jaws. The groups consistent of 50 children (33 girls, 17 boys) aged between 9 and 13.5 years were analyzed and assigned to three subgroups. Group 1= upper jaw hypodontia. Group 2= lower jaw hypodontia. Group 3= hypodontia in both jaws.
Material and methods
Eleven angular and three index measurements from lateral encephalographs and two linear measurements from dental blaster casts were calculated. All data was statistically analyzed, parameters with p<5% were investigated for each subgroup respectively.
Results
In comparison with standards the study group showed bimaxillary retrognathism and a reduction of the lower anterior facial height. Moreover both overbite and overjet significantly increased. Other values laid within the normal ranges. Evaluating results of the subgroups, differences in the means of SNA, SNB and overjet between the groups were observed. Analysis of the mandibular growth pattern revealed, that neither vertical nor horizontal patterns are dominant in hypodontia patients.
Conclusions
In certain dentofacial parameters differences between persons with hypodontia and such with full dentition exist. According to our findings agenetic teeth may have a negative influence on the saggital development of a jaw and the lower face and may be responsible for increased overbites. This should receive attention in orthodontic treatment of hypodontia patients
Brand Suicide? Memory and Liking of Negative Brand Names
Negative brand names are surprisingly common in the marketplace (e.g., Poison perfume; Hell pizza, and Monster energy drink), yet their effects on consumer behavior are currently unknown. Three studies investigated the effects of negative brand name valence on brand name memory and liking of a branded product. Study 1 demonstrates that relative to nonnegative brand names, negative brand names and their associated logos are better recognised. Studies 2 and 3 demonstrate that negative valence of a brand name tends to have a detrimental influence on product evaluation with evaluations worsening as negative valence increases. However, evaluation is also dependent on brand name arousal, with high arousal brand names resulting in more positive evaluations, such that moderately negative brand names are equally as attractive as some non-negative brand names. Study 3 shows evidence for affective habituation, whereby the effects of negative valence reduce with repeated exposures to some classes of negative brand name
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