2,505 research outputs found
New insights into Mesozoic cycad evolution: an exploration of anatomically preserved Cycadaceae seeds from the Jurassic Oxford Clay biota
Most knowledge concerning Mesozoic Era floras has come from compression fossils. This has been augmented in the last 20 years by rarer permineralized material showing cellular preservation. Here, we describe a new genus of anatomically preserved gymnosperm seed from the Callovian–Oxfordian (Jurassic) Oxford Clay Formation (UK), using a combination of traditional sectioning and synchrotron radiation X-ray micro-tomography (SRXMT). Oxfordiana motturii gen. et sp. nov. is large and bilaterally symmetrical. It has prominent external ribs, and has a three-layered integument comprising: a narrow outer layer of thick walled cells; a thick middle parenchymatous layer; and innermost a thin fleshy layer. The integument has a longitudinal interior groove and micropyle, enveloping a nucellus with a small pollen chamber. The large size, bilateral symmetry and integumentary groove demonstrate an affinity for the new species within the cycads. Moreover, the internal groove in extant taxa is an autapomorphy of the genus Cycas, where it facilitates seed germination. Based upon the unique seed germination mechanism shared with living species of the Cycadaceae, we conclude that O. motturii is a member of the stem-group lineage leading to Cycas after the Jurassic divergence of the Cycadaceae from other extant cycads. SRXMT—for the first time successfully applied to fossils already prepared as slides—reveals the distribution of different mineral phases within the fossil, and allows us to evaluate the taphonomy of Oxfordiana. An early pyrite phase replicates the external surfaces of individual cells, a later carbonate component infilling void spaces. The resulting taphonomic model suggests that the relatively small size of the fossils was key to their exceptional preservation, concentrating sulfate-reducing bacteria in a locally closed microenvironment and thus facilitating soft-tissue permineralization
Diversity of gut microflora is required for the generation of B cell with regulatory properties in a skin graft model
B cells have been reported to promote graft rejection through alloantibody production. However, there is growing evidence that B cells can contribute to the maintenance of tolerance. Here, we used a mouse model of MHC-class I mismatched skin transplantation to investigate the contribution of B cells to graft survival. We demonstrate that adoptive transfer of B cells prolongs skin graft survival but only when the B cells were isolated from mice housed in low sterility "conventional" (CV) facilities and not from mice housed in pathogen free facilities (SPF). However, prolongation of skin graft survival was lost when B cells were isolated from IL-10 deficient mice housed in CV facilities. The suppressive function of B cells isolated from mice housed in CV facilities correlated with an anti-inflammatory environment and with the presence of a different gut microflora compared to mice maintained in SPF facilities. Treatment of mice in the CV facility with antibiotics abrogated the regulatory capacity of B cells. Finally, we identified transitional B cells isolated from CV facilities as possessing the regulatory function. These findings demonstrate that B cells, and in particular transitional B cells, can promote prolongation of graft survival, a function dependent on licensing by gut microflora
Global coastal wetland change under sea-level rise and related stresses: The DIVA Wetland Change Model
The Dynamic Interactive Vulnerability Assessment Wetland Change Model (DIVA_WCM) comprises a dataset of contemporary global coastal wetland stocks (estimated at 756 × 10^3 km^2 (in 2011)), mapped to a one-dimensional global database, and a model of the macro-scale controls on wetland response to sea-level rise. Three key drivers of wetland response to sea-level rise are considered: 1) rate of sea-level rise relative to tidal range; 2) lateral accommodation space; and 3) sediment supply. The model is tuned by expert knowledge, parameterised with quantitative data where possible, and validated against mapping associated with two large-scale mangrove and saltmarsh vulnerability studies. It is applied across 12,148 coastal segments (mean length 85 km) to the year 2100. The model provides better-informed macro-scale projections of likely patterns of future coastal wetland losses across a range of sea-level rise scenarios and varying assumptions about the construction of coastal dikes to prevent sea flooding (as dikes limit lateral accommodation space and cause coastal squeeze). With 50 cm of sea-level rise by 2100, the model predicts a loss of 46–59% of global coastal wetland stocks. A global coastal wetland loss of 78% is estimated under high sea-level rise (110 cm by 2100) accompanied by maximum dike construction. The primary driver for high vulnerability of coastal wetlands to sea-level rise is coastal squeeze, a consequence of long-term coastal protection strategies. Under low sea-level rise (29 cm by 2100) losses do not exceed ca. 50% of the total stock, even for the same adverse dike construction assumptions. The model results confirm that the widespread paradigm that wetlands subject to a micro-tidal regime are likely to be more vulnerable to loss than macro-tidal environments. Countering these potential losses will require both climate mitigation (a global response) to minimise sea-level rise and maximisation of accommodation space and sediment supply (a regional response) on low-lying coasts.The authors gratefully acknowledge funding from the European Union under contract number EVK2-2000-22024. They thank all their partners in the DINAS-COAST project Dynamic and Interactive Assessment of National, Regional and Global Vulnerability of Coastal Zones to Climate Change and Sea-level rise. We are grateful to staff at UNEP-WCMC for generous access to evolving databases on global coastal wetland extent: Jon Hutton, Hannah Thomas, Jan-Willem van Bochove, Simon Blyth and Chris McOwen. Current wetland databases held at WCMC build upon the pioneering efforts of Mark Spalding and Carmen Lacambra.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.gloplacha.2015.12.01
Whole-brain functional hypoconnectivity as an endophenotype of autism in adolescents.
Endophenotypes are heritable and quantifiable markers that may assist in the identification of the complex genetic underpinnings of psychiatric conditions. Here we examined global hypoconnectivity as an endophenotype of autism spectrum conditions (ASCs). We studied well-matched groups of adolescent males with autism, genetically-related siblings of individuals with autism, and typically-developing control participants. We parcellated the brain into 258 regions and used complex-network analysis to detect a robust hypoconnectivity endophenotype in our participant group. We observed that whole-brain functional connectivity was highest in controls, intermediate in siblings, and lowest in ASC, in task and rest conditions. We identified additional, local endophenotype effects in specific networks including the visual processing and default mode networks. Our analyses are the first to show that whole-brain functional hypoconnectivity is an endophenotype of autism in adolescence, and may thus underlie the heritable similarities seen in adolescents with ASC and their relatives.The authors wish to thank the participants and their families for their participation and the autism support organisations who assisted with recruitment. We thank colleagues at the Brain Mapping Unit for methodological discussions and thank Meng-Chuan Lai, Amber Ruigrok and Richard Bethlehem for the same. Data collection was funded by a Clinical Scientist Fellowship from the UK Medical Research Council (MRC) (G0701919) to MDS. LRC was supported by the Gates Cambridge Scholarship Trust. The study was conducted in associated with the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care (CLAHRC) for Cambridgeshire, and Peterborough National Health Service (NHS) Foundation Trust. The present analysis was funded by a NARSAD Young Investigator award (to MR) and by the Isaac Newton Trust (to MR); RJFY is additionally supported by a Rubicon Fellowship from the Netherlands Organisation for Scientific Research. The Brain Mapping Unit (MR, RLM, RJFY, JS and ETB) is part of the Behavioural & Clinical Neuroscience Institute, which is funded by the MRC and the Wellcome Trust. High performance computing facilities were supported by the NIHR Cambridge Biomedical Research Centre.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.nicl.2015.07.01
Physics of Ultra-Peripheral Nuclear Collisions
Moving highly-charged ions carry strong electromagnetic fields that act as a
field of photons. In collisions at large impact parameters, hadronic
interactions are not possible, and the ions interact through photon-ion and
photon-photon collisions known as {\it ultra-peripheral collisions} (UPC).
Hadron colliders like the Relativistic Heavy Ion Collider (RHIC), the Tevatron
and the Large Hadron Collider (LHC) produce photonuclear and two-photon
interactions at luminosities and energies beyond that accessible elsewhere; the
LHC will reach a energy ten times that of the Hadron-Electron Ring
Accelerator (HERA). Reactions as diverse as the production of anti-hydrogen,
photoproduction of the , transmutation of lead into bismuth and
excitation of collective nuclear resonances have already been studied. At the
LHC, UPCs can study many types of `new physics.'Comment: 47 pages, to appear in Annual Review of Nuclear and Particle Scienc
Incidental diagnosis of diseases on un-enhanced helical computed tomography performed for ureteric colic
BACKGROUND: Patients presenting in the emergency room with flank pain suggestive of acute ureteric colic may have alternative underlying conditions mimicking ureteric stones. An early diagnosis and appropriate treatment for other causes of flank pain is important. The majority of centers around the world are increasingly using un-enhanced helical CT (UHCT) for evaluation of ureteric colic. This study was conducted to determine the incidence and spectrum of significant incidental diagnoses established or suggested on UHCT performed for suspected renal/ureteric colic. METHODS: Urologist and radiologist reviewed 233 consecutive UHCT, performed for suspected renal/ureteral colic along with assessment of the medical records. Radiological diagnoses of clinical entities not suspected otherwise were analyzed. All other relevant radiological, biochemical and serological investigations and per-operative findings were also noted. RESULTS: Ureteral calculi were identified in 148 examinations (64%), findings of recent passage of calculi in 10 (4%) and no calculus in 75 examinations (32%). Overall the incidental findings (additional or alternative diagnosis) were found in 28 (12%) CT scans. Twenty (71%) of these diagnoses were confirmed by per-operative findings, biopsy, and other radiological and biochemical investigations or on clinical follow up. CONCLUSION: A wide spectrum of significant incidental diagnoses can be identified on UHCT performed for suspected renal/ureteral colic. In the present series of 233 consecutive CT examinations, the incidence of incidental diagnosis was 12%
Impaired perception of facial motion in autism spectrum disorder
Copyright: © 2014 O’Brien et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.This article has been made available through the Brunel Open Access Publishing Fund.Facial motion is a special type of biological motion that transmits cues for socio-emotional communication and enables the discrimination of properties such as gender and identity. We used animated average faces to examine the ability of adults with autism spectrum disorders (ASD) to perceive facial motion. Participants completed increasingly difficult tasks involving the discrimination of (1) sequences of facial motion, (2) the identity of individuals based on their facial motion and (3) the gender of individuals. Stimuli were presented in both upright and upside-down orientations to test for the difference in inversion effects often found when comparing ASD with controls in face perception. The ASD group’s performance was impaired relative to the control group in all three tasks and unlike the control group, the individuals with ASD failed to show an inversion effect. These results point to a deficit in facial biological motion processing in people with autism, which we suggest is linked to deficits in lower level motion processing we have previously reported
Absence of the spleen(s) in conjoined twins: a diagnostic clue of laterality defects? Radiological study of historical specimens
Laterality defects are quite common in thoracoileopagus and parapagus dicephalus but rare in other types of conjoined twins. To present the presumed laterality defects in cephalothoracoileopagus and prosopothoracoileopagus conjoined twins, based on the unilateral or bilateral absence or duplication of the spleen. Three human anatomical specimens of craniothoracoileopagus (CTIP) twins and one of prosopothoracoileopagus (PTIP) twins were investigated. The specimens were part of the Museum Vrolik collection of the Department of Anatomy and Embryology of the Academic Medical Centre, University of Amsterdam, The Netherlands. The specimens were taken out of their jars and scanned with multidetector CT and volumetric T2-weighted MRI at 1.5 T. The internal anatomy of the specimens was largely in accordance with previous reports. However, there was no recognisable spleen in the right twin in one CTIP specimen, in the left twin in one other CTIP specimen, and in both twins in the third CTIP specimen and in the PTIP specimen. Asplenia and polysplenia are considered reliable indicators of right and left isomerism, respectively. However, three of our four specimens had laterality patterns that did not correspond with those previously reported. Since no other parameters of laterality defects could be verified in these specimens, we concluded that asplenia was unlikely to be caused by laterality defect
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