852 research outputs found
Superluminous supernovae: No threat from Eta Carinae
Recently Supernova 2006gy was noted as the most luminous ever recorded, with
a total radiated energy of ~10^44 Joules. It was proposed that the progenitor
may have been a massive evolved star similar to eta Carinae, which resides in
our own galaxy at a distance of about 2.3 kpc. eta Carinae appears ready to
detonate. Although it is too distant to pose a serious threat as a normal
supernova, and given its rotation axis is unlikely to produce a Gamma-Ray Burst
oriented toward the Earth, eta Carinae is about 30,000 times nearer than
2006gy, and we re-evaluate it as a potential superluminous supernova. We find
that given the large ratio of emission in the optical to the X-ray, atmospheric
effects are negligible. Ionization of the atmosphere and concomitant ozone
depletion are unlikely to be important. Any cosmic ray effects should be spread
out over ~10^4 y, and similarly unlikely to produce any serious perturbation to
the biosphere. We also discuss a new possible effect of supernovae, endocrine
disruption induced by blue light near the peak of the optical spectrum. This is
a possibility for nearby supernovae at distances too large to be considered
"dangerous" for other reasons. However, due to reddening and extinction by the
interstellar medium, eta Carinae is unlikely to trigger such effects to any
significant degree.Comment: 19 pages, 2 figures; Revised version as accepted for publication in
Astrobiolog
Overt and subtle discrimination and psychological well-being:Examining the mediating and moderating role of ethnic-racial identity among emerging adults
Ethnic-racial identity (ERI) has been reported as mediator and moderator of the relation between discrimination and psychological well-being. However, it remains unclear how different forms of discrimination (i.e., overt and subtle) predict well-being over time, and whether ERI exploration and commitment mediate or moderate this association. This preregistered study explored the associations of overt and subtle discrimination with well-being (i.e., depression, substance use, life satisfaction) in a sample of 323 ethnic-racial minoritized college students (M age W1 = 18.03, 62.7% female) from longitudinal data collected in the US. Cross-lagged panel models across three waves indicated no associations of overt discrimination, but participants experiencing more subtle discrimination during their transition to college reported more depressive symptoms after four months. Ethnic-racial identity did not function as mediator or moderator. Findings indicate the need for a more nuanced understanding of the role of ERI during emerging adulthood.</p
Mitochondrial DNA common deletion is not associated with thyroid, breast and colorectal tumors in Turkish patients
Recently, efforts have been focused on mitochondrial DNA changes and their relation to human cancers. Among them, a 4977 bp deletion of mitochondrial DNA, named “common deletion”, has been investigated in several types of tumors, with inconsistent results. In this study, we investigated the presence of the common deletion in tissues from 25 breast, 25 colorectal and 50 thyroid tumors and in the adjacent healthy tissues from Turkish patients. Samples from healthy volunteers were also evaluated for comparison. Two PCR-based methods were used for the detection of the common deletion. First, two pairs of primers were used to amplify wild-type and deleted mtDNA. Then, a highly sensitive nested-PCR was performed, to determine low amounts of deleted genomes. By the first method, wild-type mtDNAs were observed in all samples, but a deletion was observed in only six thyroid samples, by using the nested-PCR method. In conclusion, the mitochondrial common deletion was very rare in our study group and did not appear to be not related with cancer
Cost-effectiveness of sorafenib for treatment of radioactive iodine (rai)-refractory locally advanced/metastatic differentiated thyroid cancer (dtc) in Turkey
WOS: 000354498503198OBJECTIVES: Sorafenib is the first product approved for treatment of RAI refractory locally advanced/metastatic DTC patients. This study was conducted in order to analyze cost-effectiveness of sorafenib for treatment of patients with RAI refractory locally advanced/metastatic DTC in Turkey. METHODS: A cohort partition model assigning patients to one of three health states according to the proportion of patients who are progression-free, progressed, or dead in each 28-days cycle was adapted to Turkish setting. The incremental cost-effectiveness ratios (ICER) were calculated per quality-adjusted life years (QALYs) and life-years (LYs) gained. Turkish payer’s perspective was taken and time-horizon was set as patient’s lifetime (maximum 30 years). Sorafenib was compared to the best supportive care (BSC) within the model since there are no agents for treatment of patients on this stage of the disease. Essential clinical inputs were derived from DECISION trial and local resource-utilization data were based on expert opinions through an expert panel. Sensitivity of the results was evaluated in terms of key inputs by deterministic oneway and probabilistic sensitivity analyses. All costs were calculated in Turkish Liras (TL) and converted to USD using TL/USD currency rate as 2.2 (mid-2014). RESULTS: Total cost of sorafenib-treated patients is 24,384 USD higher compared to BSC. Besides, sorafenib is associated with increments of 1.29 LYs and 0.80 QALYs compared to BSC. The ICER of sorafenib per LYs and QALYs gained compared to BSC were determined as 18,851 USD and 30,485 USD respectively. One-way sensitivity analysis demonstrated that results are not sensitive to the changes in model inputs and pharmacoeconomic analysis results were validated by probabilistic sensitivity analysis. CONCLUSIONS: Sorafenib is cost-effective for treatment of patients with RAI refractory locally advanced/metastatic DTC compared to BSC with an ICER value below the willingness-to-pay threshold (3-times GDP per capita ─ 32,346 USD) for Turkey
Fashion, Cooperation, and Social Interactions
Fashion plays such a crucial rule in the evolution of culture and society
that it is regarded as a second nature to the human being. Also, its impact on
economy is quite nontrivial. On what is fashionable, interestingly, there are
two viewpoints that are both extremely widespread but almost opposite:
conformists think that what is popular is fashionable, while rebels believe
that being different is the essence. Fashion color is fashionable in the first
sense, and Lady Gaga in the second. We investigate a model where the population
consists of the afore-mentioned two groups of people that are located on social
networks (a spatial cellular automata network and small-world networks). This
model captures two fundamental kinds of social interactions (coordination and
anti-coordination) simultaneously, and also has its own interest to game
theory: it is a hybrid model of pure competition and pure cooperation. This is
true because when a conformist meets a rebel, they play the zero sum matching
pennies game, which is pure competition. When two conformists (rebels) meet,
they play the (anti-) coordination game, which is pure cooperation. Simulation
shows that simple social interactions greatly promote cooperation: in most
cases people can reach an extraordinarily high level of cooperation, through a
selfish, myopic, naive, and local interacting dynamic (the best response
dynamic). We find that degree of synchronization also plays a critical role,
but mostly on the negative side. Four indices, namely cooperation degree,
average satisfaction degree, equilibrium ratio and complete ratio, are defined
and applied to measure people's cooperation levels from various angles. Phase
transition, as well as emergence of many interesting geographic patterns in the
cellular automata network, is also observed.Comment: 21 pages, 12 figure
Late-onset erythromelalgia in a previously healthy young woman: a case report and review of the literature
<p>Abstract</p> <p>Introduction</p> <p>Erythromelalgia is a rare disorder characterized by episodic erythema and burning pain, which commonly involves the extremities. We present a case of late onset erythromelalgia in a previously healthy young woman and briefly review the literature. Our patient's case also has additional uncommon features not reported previously.</p> <p>Case presentation</p> <p>A 33-year-old previously healthy Caucasian woman presented with complaints of episodic burning pain and flushing occurring in a central distribution involving her face, ears, upper chest and, occasionally, her upper extremities. Her symptoms were triggered by lying down or warm temperature exposure and were relieved by cooling measures. Extensive diagnostic work-up looking for secondary causes for the symptoms was negative and the diagnosis of erythromelalgia was made based on details provided in her clinical history supported by raised temperature in the affected area measured by thermography during a symptomatic episode. The patient did not respond to pharmacological therapy or surgical sympathectomy. She was advised on lifestyle modification to avoid activities which triggered her symptoms. She was hypothermic with a core temperature between 92 and 95°F. She also had premature ovarian failure, which had not previously been reported.</p> <p>Conclusion</p> <p>Erythromelalgia is a rare disorder of unknown cause. There is no confirmatory diagnostic test; diagnosis is based on details provided in the patient's medical history and physical examination during the episodes. For those affected, this disorder leads to significant long-term morbidity and unfortunately, to date, no definitive therapy is available except for lifestyle modification.</p
Survival of Naïve T Cells Requires the Expression of Let-7 miRNAs
Maintaining the diversity and constant numbers of naïve T cells throughout the organism's lifetime is necessary for efficient immune responses. Naïve T cell homeostasis, which consists of prolonged survival, occasional proliferation and enforcement of quiescence, is tightly regulated by multiple signaling pathways which are in turn controlled by various transcription factors. However, full understanding of the molecular mechanisms underlying the maintenance of the peripheral T cell pool has not been achieved. In the present study, we demonstrate that T cell-specific deficiency in let-7 miRNAs results in peripheral T cell lymphopenia resembling that of Dicer1 knockout mice. Deletion of let-7 leads to profound T cell apoptosis while overexpression prevents it. We further show that in the absence of let-7, T cells cannot sustain optimal levels of the pro-survival factor Bcl2 in spite of the intact IL-7 signaling, and re-expression of Bcl2 in let-7 deficient T cells completely rescues the survival defect. Thus, we have uncovered a novel let-7-dependent mechanism of post-transcriptional regulation of naïve T cell survival in vivo
Dynamics in online social networks
An increasing number of today's social interactions occurs using online
social media as communication channels. Some online social networks have become
extremely popular in the last decade. They differ among themselves in the
character of the service they provide to online users. For instance, Facebook
can be seen mainly as a platform for keeping in touch with close friends and
relatives, Twitter is used to propagate and receive news, LinkedIn facilitates
the maintenance of professional contacts, Flickr gathers amateurs and
professionals of photography, etc. Albeit different, all these online platforms
share an ingredient that pervades all their applications. There exists an
underlying social network that allows their users to keep in touch with each
other and helps to engage them in common activities or interactions leading to
a better fulfillment of the service's purposes. This is the reason why these
platforms share a good number of functionalities, e.g., personal communication
channels, broadcasted status updates, easy one-step information sharing, news
feeds exposing broadcasted content, etc. As a result, online social networks
are an interesting field to study an online social behavior that seems to be
generic among the different online services. Since at the bottom of these
services lays a network of declared relations and the basic interactions in
these platforms tend to be pairwise, a natural methodology for studying these
systems is provided by network science. In this chapter we describe some of the
results of research studies on the structure, dynamics and social activity in
online social networks. We present them in the interdisciplinary context of
network science, sociological studies and computer science.Comment: 17 pages, 4 figures, book chapte
İzmir‐Ankara suture as a Triassic to Cretaceous plate boundary – data from central Anatolia
The İzmir‐Ankara suture represents part of the boundary between Laurasia and Gondwana along which a wide Tethyan ocean was subducted. In northwest Turkey, it is associated with distinct oceanic subduction‐accretion complexes of Late Triassic, Jurassic and Late Cretaceous ages. The Late Triassic and Jurassic accretion complexes consist predominantly of basalt with lesser amounts of shale, limestone, chert, Permian (274 Ma zircon U‐Pb age) metagabbro and serpentinite, which have undergone greenschist facies metamorphism. Ar‐Ar muscovite ages from the phyllites range from 210 Ma down to 145 Ma with a broad southward younging. The Late Cretaceous subduction‐accretion complex, the ophiolitic mélange, consists of basalt, radiolarian chert, shale and minor amounts of recrystallized limestone, serpentinite and greywacke, showing various degrees of blueschist facies metamorphism and penetrative deformation. Ar‐Ar phengite ages from two blueschist metabasites are ca. 80 Ma (Campanian). The ophiolitic mélange includes large Jurassic peridotite‐gabbro bodies with plagiogranites with ca. 180 Ma U‐Pb zircon ages. Geochronological and geological data show that Permian to Cretaceous oceanic lithosphere was subducted north under the Pontides from the Late Triassic to the Late Cretaceous. This period was characterized generally by subduction‐accretion, except in the Early Cretaceous, when subduction‐erosion took place. In the Sakarya segment all the subduction accretion complexes, as well as the adjacent continental sequences, are unconformably overlain by Lower Eocene red beds. This, along with the stratigraphy of the Sakarya Zone indicate that the hard collision between the Sakarya Zone and the Anatolide‐Tauride Block took place in Paleocene
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