559 research outputs found

    Ultra-fast early Miocene exhumation of Cavalli Seamount, Northland Plateau, Southwest Pacific Ocean

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    We present new photographic, petrological, geochronological, and isotopic data for gneissic and granitic rocks obtained from six sample stations on Cavalli Seamount during two cruises in 2002. These data lead to revision of earlier conclusions based on two dredges of schist in 1999. Based on c. 100 Ma ages of zircon cores, and whole rock petrochemistry and tracer isotopes, we interpret the protoliths of paragneisses and orthogneisses to probably have been sedimentary and plutonic correlatives of the Late Cretaceous Houhora Complex. U‐Pb dating of low Th/U zircon rims confirms an earliest Miocene high‐grade metamorphic episode. A cooling history based on Ar‐Ar K‐feldspar dating indicates ultra‐rapid cooling (c. 2000°C/m.y.) and vertical exhumation (c. 100 mm/yr) of the rocks at 19.9 Ma. Our preferred tectonic model relates the amphibolite facies metamorphism to Northland Allochthon emplacement and the rapid exhumation to dextral transtension along the Vening Meinesz Fracture Zone system and/or a rapidly retreating Pacific trench

    Free Will in a Quantum World?

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    In this paper, I argue that Conway and Kochen’s Free Will Theorem (1,2) to the conclusion that quantum mechanics and relativity entail freedom for the particles, does not change the situation in favor of a libertarian position as they would like. In fact, the theorem more or less implicitly assumes that people are free, and thus it begs the question. Moreover, it does not prove neither that if people are free, so are particles, nor that the property people possess when they are said to be free is the same as the one particles possess when they are claimed to be free. I then analyze the Free State Theorem (2), which generalizes the Free Will Theorem without the assumption that people are free, and I show that it does not prove anything about free will, since the notion of freedom for particles is either inconsistent, or it does not concern our common understanding of freedom. In both cases, the Free Will Theorem and the Free State Theorem do not provide any enlightenment on the constraints physics can pose on free will

    Child/Adolescent Anxiety Multimodal Study (CAMS): rationale, design, and methods

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    <p>Abstract</p> <p>Objective</p> <p>To present the design, methods, and rationale of the Child/Adolescent Anxiety Multimodal Study (CAMS), a recently completed federally-funded, multi-site, randomized placebo-controlled trial that examined the relative efficacy of cognitive-behavior therapy (CBT), sertraline (SRT), and their combination (COMB) against pill placebo (PBO) for the treatment of separation anxiety disorder (SAD), generalized anxiety disorder (GAD) and social phobia (SoP) in children and adolescents.</p> <p>Methods</p> <p>Following a brief review of the acute outcomes of the CAMS trial, as well as the psychosocial and pharmacologic treatment literature for pediatric anxiety disorders, the design and methods of the CAMS trial are described.</p> <p>Results</p> <p>CAMS was a six-year, six-site, randomized controlled trial. Four hundred eighty-eight (N = 488) children and adolescents (ages 7-17 years) with DSM-IV-TR diagnoses of SAD, GAD, or SoP were randomly assigned to one of four treatment conditions: CBT, SRT, COMB, or PBO. Assessments of anxiety symptoms, safety, and functional outcomes, as well as putative mediators and moderators of treatment response were completed in a multi-measure, multi-informant fashion. Manual-based therapies, trained clinicians and independent evaluators were used to ensure treatment and assessment fidelity. A multi-layered administrative structure with representation from all sites facilitated cross-site coordination of the entire trial, study protocols and quality assurance.</p> <p>Conclusions</p> <p>CAMS offers a model for clinical trials methods applicable to psychosocial and psychopharmacological comparative treatment trials by using state-of-the-art methods and rigorous cross-site quality controls. CAMS also provided a large-scale examination of the relative and combined efficacy and safety of the best evidenced-based psychosocial (CBT) and pharmacologic (SSRI) treatments to date for the most commonly occurring pediatric anxiety disorders. Primary and secondary results of CAMS will hold important implications for informing practice-relevant decisions regarding the initial treatment of youth with anxiety disorders.</p> <p>Trial registration</p> <p>ClinicalTrials.gov NCT00052078.</p

    SMARTer Discontinuation Trial Designs for Developing an Adaptive Treatment Strategy

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    Abstract Objective: Developing evidenced-based practices for the management of childhood psychiatric disorders requires research studies that address how to treat children during both the acute phase of the disorder and beyond. Given the selection of a medication for acute treatment, discontinuation trials are used to evaluate the effects of treatment duration (e.g., time on medication) and/or maintenance strategies following successful acute-phase treatment. Recently, sequential multiple assignment randomized trials (SMART) have been proposed for use in informing sequences of critical clinical decisions such as those mentioned. The objective of this article is to illustrate how a SMART study is related to the standard discontinuation trial design, while addressing additional clinically important questions with similar trial resources. Method: The recently completed Child/Adolescent Anxiety Multimodal Study (CAMS), a randomized trial that examined the relative efficacy of three acute-phase treatments for pediatric anxiety disorders, along with a next logical step, a standard discontinuation trial design, is used to clarify the ideas. This example is used to compare the discontinuation trial design relative to the SMART design. Results: We find that the standard discontinuation trial can be modified slightly using a SMART design to yield high-quality data that can be used to address a wider variety of questions in addition to the impact of treatment duration. We discuss how this innovative trial design is ultimately more efficient and less costly than the standard discontinuation trial, and may result in more representative comparisons between treatments. Conclusions: Mental health researchers who are interested in addressing questions concerning the effects of continued treatment (for different durations) following successful acute-phase treatment should consider SMART designs in place of discontinuation trial designs in their research. SMART designs can be used to address these and other questions concerning individualized sequences of treatment, such as the choice of a rescue treatment in case of postacute phase relapse.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98496/1/cap%2E2011%2E0073.pd

    A study of lymph node ratio in stage IV colorectal cancer

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    which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background: The finding of metastasis in colorectal cancer, stage IV disease, has a major impact on prognosis and treatment strategy. Known important factors include the extent of the metastasis and the patients &apos; performance status. The lymph node factors are of known importance in earlier cancer stages but less described in metastatic disease. The aim of the study was to evaluate lymph node status and ratio as prognostic markers in stage IV colorectal cancer. Methods: The study was retrospective and assessing all patients operated, with bowel resection, for an initial stage IV colorectal cancer during 1999–2003 (n = 136). Basic demographic data as well as given treatment was assessed. The Lymph node ratio (LNR), the quota between the number of lymph node metastasis and assessed lymph nodes, was calculated. LNR groups were created by ratio thirds, 3 equally sized groups. The analysis was made by LNR group and by eligibility for chemotherapy with cancer specific survival as outcome parameter. Results: The median survival (CSS) for the entire group was 431 days with great variability. For the patients eligible for chemotherapy it ranged from 791 days in LNR-group 1 to 433 days for th

    Vasospasm in children with traumatic brain injury

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    To determine the incidence of vasospasm in children who have suffered moderate to severe traumatic brain injury. A prospective observational pilot study in a 24-bed pediatric intensive care unit was performed. Twenty-two children aged 7 months to 14 years with moderate to severe traumatic brain injury as indicated by Glasgow Coma Score ≤12 and abnormal head imaging were enrolled. Transcranial Doppler ultrasound was performed to identify and follow vasospasm. Patients with a flow velocity in the middle cerebral artery (MCA) &gt;120 cm/s were considered to have vasospasm by criterion A. If flow velocity in the MCA was &gt;120 cm/s and the Lindegaard ratio was &gt;3, vasospasm was considered to be present by criterion B. Patients with basilar artery (BA) flow velocity &gt;90 cm/s met criteria for vasospasm in the posterior circulation (criterion C). In the MCA, 45.5% of patients developed vasospasm based on criterion A and 36.3% developed vasospasm based on criterion B. A total of 18.2% of patients developed vasospasm in the BA by criterion C. Typical day of onset of vasospasm was hospital day 2–3. Duration of vasospasm in the anterior circulation was 4 ± 2 days based on criteria A and 3 ± 1 days based on criteria B. Vasospasm in the posterior circulation persisted for 2 ± 1 days. Using the adult criteria outlined above to diagnose vasospasm, a significant proportion of pediatric patients who have suffered moderate to severe traumatic brain injury develop vasospasm during the course of their treatment

    Prime movers : mechanochemistry of mitotic kinesins

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    Mitotic spindles are self-organizing protein machines that harness teams of multiple force generators to drive chromosome segregation. Kinesins are key members of these force-generating teams. Different kinesins walk directionally along dynamic microtubules, anchor, crosslink, align and sort microtubules into polarized bundles, and influence microtubule dynamics by interacting with microtubule tips. The mechanochemical mechanisms of these kinesins are specialized to enable each type to make a specific contribution to spindle self-organization and chromosome segregation

    Nature's Swiss Army Knives: Ovipositor Structure Mirrors Ecology in a Multitrophic Fig Wasp Community

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    Resource partitioning is facilitated by adaptations along niche dimensions that range from morphology to behaviour. The exploitation of hidden resources may require specially adapted morphological or sensory tools for resource location and utilisation. Differences in tool diversity and complexity can determine not only how many species can utilize these hidden resources but also how they do so.The sclerotisation, gross morphology and ultrastructure of the ovipositors of a seven-member community of parasitic wasps comprising of gallers and parasitoids developing within the globular syconia (closed inflorescences) of Ficus racemosa (Moraceae) was investigated. These wasps also differ in their parasitism mode (external versus internal oviposition) and their timing of oviposition into the expanding syconium during its development. The number and diversity of sensilla, as well as ovipositor teeth, increased from internally ovipositing to externally ovipositing species and from gallers to parasitoids. The extent of sclerotisation of the ovipositor tip matched the force required to penetrate the syconium at the time of oviposition of each species. The internally ovipositing pollinator had only one type of sensillum and a single notch on the ovipositor tip. Externally ovipositing species had multiple sensilla types and teeth on their ovipositors. Chemosensilla were most concentrated at ovipositor tips while mechanoreceptors were more widely distributed, facilitating the precise location of hidden hosts in these wasps which lack larval host-seeking behaviour. Ovipositor traits of one parasitoid differed from those of its syntopic galler congeners and clustered with those of parasitoids within a different wasp subfamily. Thus ovipositor tools can show lability based on adaptive necessity, and are not constrained by phylogeny.Ovipositor structure mirrored the increasingly complex trophic ecology and requirements for host accessibility in this parasite community. Ovipositor structure could be a useful surrogate for predicting the biology of parasites in other communities

    Lithic technological responses to Late Pleistocene glacial cycling at Pinnacle Point Site 5-6, South Africa

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    There are multiple hypotheses for human responses to glacial cycling in the Late Pleistocene, including changes in population size, interconnectedness, and mobility. Lithic technological analysis informs us of human responses to environmental change because lithic assemblage characteristics are a reflection of raw material transport, reduction, and discard behaviors that depend on hunter-gatherer social and economic decisions. Pinnacle Point Site 5-6 (PP5-6), Western Cape, South Africa is an ideal locality for examining the influence of glacial cycling on early modern human behaviors because it preserves a long sequence spanning marine isotope stages (MIS) 5, 4, and 3 and is associated with robust records of paleoenvironmental change. The analysis presented here addresses the question, what, if any, lithic assemblage traits at PP5-6 represent changing behavioral responses to the MIS 5-4-3 interglacial-glacial cycle? It statistically evaluates changes in 93 traits with no a priori assumptions about which traits may significantly associate with MIS. In contrast to other studies that claim that there is little relationship between broad-scale patterns of climate change and lithic technology, we identified the following characteristics that are associated with MIS 4: increased use of quartz, increased evidence for outcrop sources of quartzite and silcrete, increased evidence for earlier stages of reduction in silcrete, evidence for increased flaking efficiency in all raw material types, and changes in tool types and function for silcrete. Based on these results, we suggest that foragers responded to MIS 4 glacial environmental conditions at PP5-6 with increased population or group sizes, 'place provisioning', longer and/or more intense site occupations, and decreased residential mobility. Several other traits, including silcrete frequency, do not exhibit an association with MIS. Backed pieces, once they appear in the PP5-6 record during MIS 4, persist through MIS 3. Changing paleoenvironments explain some, but not all temporal technological variability at PP5-6.Social Science and Humanities Research Council of Canada; NORAM; American-Scandinavian Foundation; Fundacao para a Ciencia e Tecnologia [SFRH/BPD/73598/2010]; IGERT [DGE 0801634]; Hyde Family Foundations; Institute of Human Origins; National Science Foundation [BCS-9912465, BCS-0130713, BCS-0524087, BCS-1138073]; John Templeton Foundation to the Institute of Human Origins at Arizona State Universit

    Increased Local Retention of Reef Coral Larvae as a Result of Ocean Warming

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    Climate change will alter many aspects of the ecology of organisms, including dispersal patterns and population connectivity. Understanding these changes is essential to predict future species distributions, estimate potential for adaptation, and design effective networks of protected areas. In marine environments, dispersal is often accomplished by larvae. At higher temperatures, larvae develop faster, but suffer higher mortality, making the effect of temperature on dispersal difficult to predict. Here, we experimentally calibrate the effect of temperature on larval survival and settlement in a dynamic model of coral dispersal. Our findings imply that most reefs globally will experience several-fold increases in local retention of larvae due to ocean warming. This increase will be particularly pronounced for reefs with mean water residence times comparable to the time required for species to become competent to settle. Higher local retention rates strengthen the link between abundance and recruitment at the reef scale, suggesting that populations will be more responsive to local conservation actions. Higher rates of local retention and mortality will weaken connectivity between populations, and thus potentially retard recovery following severe disturbances that substantially deplete local populations. Conversely, on isolated reefs that are dependent on replenishment from local broodstock, increases in local retention may hasten recovery
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