5,175 research outputs found

    Gamma-ray bursts and X-ray melting of material as a potential source of chondrules and planets

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    The intense radiation from a gamma-ray burst (GRB) is shown to be capable of melting stony material at distances up to 300 light years which subsequently cool to form chondrules. These conditions were created in the laboratory for the first time when millimeter sized pellets were placed in a vacuum chamber in the white synchrotron beam at the European Synchrotron Radiation Facility (ESRF). The pellets were rapidly heated in the X-ray and gamma-ray furnace to above 1400 C melted and cooled. This process heats from the inside unlike normal furnaces. The melted spherical samples were examined with a range of techniques and found to have microstructural properties similar to the chondrules that come from meteorites. This experiment demonstrates that GRBs can melt precursor material to form chondrules that may subsequently influence the formation of planets. This work extends the field of laboratory astrophysics to include high power synchrotron sources.Comment: 8 pages, 10 figures. Proceedings of the 5th INTEGRAL Workshop, Munich 16-20 February 2004. High resolution figures available at http://bermuda.ucd.ie/%7Esmcbreen/papers/duggan_01.pd

    Vol. 27, No. 2

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    Contents: Labor Relations in Hard Times, by Michael J. Duggan, Julie E. Lewis, and Mallory Milluzzi Recent Developmentshttps://scholarship.kentlaw.iit.edu/iperr/1050/thumbnail.jp

    Low-dose stereotactic radiosurgery is inadequate for medically intractable mesial temporal lobe epilepsy: a case report

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    AbstractThe successful surgical treatment of medically refractory epilepsy is based on one of three different principles: (1) elimination of the epileptic focus, (2) interruption of the pathways of neural propagation, and (3) increasing the seizure threshold through cerebral lesions or electrical stimulation. Temporal lobe epilepsy, being the most common focal epilepsy, may ultimately require temporal lobectomy. This is a case report of a 36-year-old male with drug-resistant right mesial temporal lobe epilepsy who failed to obtain seizure control after stereotactic radiosurgery to the seizure focus. Complex-partial seizures occurred 6–7 times monthly, and consisted of a loss of awareness followed by involuntary movements of the right arm. EEG/CC TV monitoring indicated a right mesial temporal lobe focus, which was corroborated by decreased uptake in the right temporal lobe by FDG-PET and by MRI findings of right hippocampal sclerosis. Stereotactic radiosurgery was performed with a 4MV linac, utilizing three isocenters with collimator sizes of 10, 10, and 7 mm respectively. A dose of 1500 cGy (max dose 2535 cGy) was delivered in a single fraction to the patient’s right amygdala and hippocampus. There were no acute complications. Following radiosurgery the patient’s seizures were improved in both frequency and intensity for approximately 3 months. Antiepileptic medications were continued. Thereafter, seizures increased in both frequency and intensity, occurring 10–20 times monthly. At 1 year post radiosurgery, standard right temporal lobectomy including amygdalohippocampectomy was performed with subsequent resolution of complex-partial seizures. Histopathology of the resected temporal lobe revealed hippocampal cell loss and fibrillary astrocytosis, consistent with hippocampal sclerosis. No radiation-induced histopathologic changes were seen. We conclude that low-dose radiosurgery doses temporarily changed the intensity and character of seizure activity, but actually increased seizure activity long-term. If radiosurgery is to be an effective alternative to temporal lobectomy for medically intractable temporal lobe epilepsy, higher radiosurgery doses will be required. The toxicity and efficacy of higher-dose radiosurgery is currently under investigation

    A mixed-methods study exploring the characteristics and needs of long-stay patients in high and medium secure settings in England: implications for service organisation

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    Background: Forensic psychiatric services provide care for those with mental disorders and offending behaviour. Concerns have been expressed that patients may stay for too long in too high levels of security. The economic burden of these services is high, and they are highly restrictive for patients. There is no agreed standard for ‘long stay’; we defined a length of stay exceeding 5 years in medium secure care, 10 years in high secure care or 15 years in a combination of both settings as long stay. Objectives: To (1) estimate the number of long-stay patients in secure settings; (2) describe patients’ characteristics, needs and care pathways and the reasons for their prolonged stay; (3) identify patients’ perceptions of their treatment and quality of life; and (4) explore stakeholders’ views on long stay. Design: A mixed-methods approach, including a cross-sectional survey (on 1 April 2013) of all patients in participating units to identify long-stay patients [work package (WP) 1], file reviews and consultant questionnaires for long-stay patients (WP2), interviews with patients (WP3) and focus groups with other stakeholders (WP4). Setting: All three high secure hospitals and 23 medium secure units (16 NHS and 9 independent providers) in England. Participants: Information was gathered on all patients in participating units (WP1), from which 401 long-stay patients were identified (WP2), 40 patients (WP3), 17 international and 31 UK experts were interviewed and three focus groups were held (WP4). Results: Approximately 23.5% of high secure patients and 18% of medium secure patients were long-stay patients. We estimated that there are currently about 730 forensic long-stay patients in England. The source of a patient’s admission and the current section of the Mental Health Act [Great Britain. Mental Health Act 1983 (as Amended by the Mental Health Act 2007). London: The Stationery Office; 2007] under which they were admitted predicted long-stay status. Long-stay patients had complex pathways, moving ‘around’ between settings rather than moving forward. They were most likely to be detained under a hospital order with restrictions (section 37/41) and to have disturbed backgrounds with previous psychiatric admissions, self-harm and significant offending histories. The most common diagnosis was schizophrenia, but 47% had been diagnosed with personality disorder. Only 50% had current formal psychological therapies. The rates of violent incidents within institutions and seclusion were high, and a large proportion had unsuccessful referrals to less secure settings. Most patients had some contact with their families. We identified five classes of patients within the long-stay sample with different characteristics. Patients differed in their attribution of reasons for long stay (internal/external), outlook (positive/negative), approach (active/passive) and readiness for change. Other countries have successfully developed specific long-stay services; however, UK experts were reluctant to accept the reality of long stay and that the medical model of ‘cure’ does not work with this group. Limitations: We did not conduct file reviews on non-long-stay patients; therefore, we cannot say which factors differentiate between long-stay patients and non-long-stay patients. Conclusions: The number of long-stay patients in England is high, resulting in high resource use. Significant barriers were identified in developing designated long-stay services. Without a national strategy, these issues are likely to remain. Future work: To compare long-stay patients and non-long-stay patients. To evaluate new service models specifically designed for long-stay patients. Study registration: The National Institute for Health Research (NIHR) Clinical Research Network Portfolio 129376. Funding: The NIHR Health Services and Delivery Research programm

    Why is there no queer international theory?

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    Over the last decade, Queer Studies have become Global Queer Studies, generating significant insights into key international political processes. Yet, the transformation from Queer to Global Queer has left the discipline of International Relations largely unaffected, which begs the question: if Queer Studies has gone global, why has the discipline of International Relations not gone somewhat queer? Or, to put it in Martin Wight’s provocative terms, why is there no Queer International Theory? This article claims that the presumed non-existence of Queer International Theory is an effect of how the discipline of International Relations combines homologization, figuration, and gentrification to code various types of theory as failures in order to manage the conduct of international theorizing in all its forms. This means there are generalizable lessons to be drawn from how the discipline categorizes Queer International Theory out of existence to bring a specific understanding of International Relations into existence

    The Broad Absorption Line Tidal Disruption Event iPTF15af: Optical and Ultraviolet Evolution

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    We present multi-wavelength observations of the tidal disruption event (TDE) iPTF15af, discovered by the intermediate Palomar Transient Factory (iPTF) survey at redshift z=0.07897z=0.07897. The optical and ultraviolet (UV) light curves of the transient show a slow decay over five months, in agreement with previous optically discovered TDEs. It also has a comparable black-body peak luminosity of Lpeak≈1.5×1044L_{\rm{peak}} \approx 1.5 \times 10^{44} erg/s. The inferred temperature from the optical and UV data shows a value of (3−-5) ×104\times 10^4 K. The transient is not detected in X-rays up to LX<3×1042L_X < 3 \times 10^{42}erg/s within the first five months after discovery. The optical spectra exhibit two distinct broad emission lines in the He II region, and at later times also Hα\alpha emission. Additionally, emission from [N III] and [O III] is detected, likely produced by the Bowen fluorescence effect. UV spectra reveal broad emission and absorption lines associated with high-ionization states of N V, C IV, Si IV, and possibly P V. These features, analogous to those of broad absorption line quasars (BAL QSOs), require an absorber with column densities NH>1023N_{\rm{H}} > 10^{23} cm−2^{-2}. This optically thick gas would also explain the non-detection in soft X-rays. The profile of the absorption lines with the highest column density material at the largest velocity is opposite that of BAL QSOs. We suggest that radiation pressure generated by the TDE flare at early times could have provided the initial acceleration mechanism for this gas. Spectral UV line monitoring of future TDEs could test this proposal.Comment: 20 pages, 12 figures, published in Ap

    Assay of matrix metalloproteinases types 1, 2, 3 and 9 in breast cancer.

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    Matrix metalloproteinases (MMPs) are zinc dependent endopeptidases implicated in cancer invasion and metastasis. Gelatin zymography was performed on 84 human breast carcinomas and seven normal breast tissues. The precursor form of MMP-2 (72 kDa) was found in 11 (12%) samples, while its two activated forms, i.e. 62 kDa and 59 kDa, were found in three (6%) and 34 (40%) samples respectively. In contrast to MMP-2, most of the samples (52%) contained MMP-9 in its precursor form. Using ELISA, MMP-1 levels were found in 12% of the samples while MMP-3 levels were found in only 2% of the samples. Levels of MMP-2, -3 and -9 correlated inversely with numbers of nodal metastases. Neither MMP-2 nor -9 levels were significantly related to patient outcome. However, patients with high levels of a 50-kDa gelatinase band after zymography had a significantly better survival than patients with low levels. This species was never observed in normal breast tissue
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