Multi-GeV Electron Acceleration in Wakefields Strongly Driven by Oversized Laser Spots.

Experiments were performed on laser wakefield acceleration in the highly nonlinear regime. With laser powers P<250 TW and using an initial spot size larger than the matched spot size for guiding, we were able to accelerate electrons to energies E_{max}>2.5 GeV, in fields exceeding 500 GV m^{-1}, with more than 80 pC of charge at energies E>1 GeV. Three-dimensional particle-in-cell simulations show that using an oversized spot delays injection, avoiding beam loss as the wakefield undergoes length oscillation. This enables injected electrons to remain in the regions of highest accelerating fields and leads to a doubling of energy gain as compared to results from using half the focal length with the same laser.

Observation of Laser Power Amplification in a Self-Injecting Laser Wakefield Accelerator.

We report on the depletion and power amplification of the driving laser pulse in a strongly driven laser wakefield accelerator. Simultaneous measurement of the transmitted pulse energy and temporal shape indicate an increase in peak power from 187±11 TW to a maximum of 318±12 TW after 13 mm of propagation in a plasma density of 0.9×10^{18} cm^{-3}. The power amplification is correlated with the injection and acceleration of electrons in the nonlinear wakefield. This process is modeled by including a localized redshift and subsequent group delay dispersion at the laser pulse front.

Risk of Injury According to Attention Deficit Hyperactivity Disorder, Comorbid Mental Illness, and Medication Therapy.

INTRODUCTION: We identify the risk of selected types of injuries among patients with ADHD or ADHD and comorbid mental illness. We also assess whether selected medications used by patients with ADHD increase the risk of comorbid mental illness or influence the association between ADHD and injury. METHODS: A retrospective cohort study design was conducted using medical claims data from the Deseret Mutual Benefit Administrators (DMBA). ADHD diagnosis, injury, medication, and demographic data were extracted from claims files during 2001-2013. Rate ratios were adjusted for age, sex, and calendar year. RESULTS: Patients with ADHD were 7.9 (95% CI 7.6-8.2) times more likely to have psychosis, 5.5 (3.9-7.8) times more likely to have alcohol- or drug-induced psychosis, and 6.0 (5.9-6.2) times more likely to have neurotic or personality disorder. Therapy with amphetamine was positively associated with neurotic or personality disorder (rate ratio=1.08, 1.02-1.15); methylphenidate was negatively associated with neurotic or personality disorder (0.90, 0.84-0.97); and atomoxetine was positively associated with psychosis (1.33, 1.21-1.46), alcohol- or drug-induced psychosis (2.38, 1.04-5.43), and neurotic or personality disorder (2.38, 1.04-5.43). ADHD was associated with an increased risk of injury, with ADHD and comorbid mental illness having a stronger increased risk of injury. Psychostimulants ameliorated the increased risk of injury for patients with ADHD. CONCLUSION: Patients with ADHD have an increased risk of injury, significantly more so for those with ADHD and comorbid mental illness. Psychostimulants can lower the risk of injury among patients with ADHD.

Rayleigh-Taylor instability of an ultrathin foil accelerated by the radiation pressure of an intense laser.

We report experimental evidence for a Rayleigh-Taylor-like instability driven by radiation pressure of an ultraintense (10(21) W/cm(2)) laser pulse. The instability is witnessed by the highly modulated profile of the accelerated proton beam produced when the laser irradiates a 5 nm diamondlike carbon (90% C, 10% H) target. Clear anticorrelation between bubblelike modulations of the proton beam and transmitted laser profile further demonstrate the role of the radiation pressure in modulating the foil. Measurements of the modulation wavelength, and of the acceleration from Doppler-broadening of back-reflected light, agree quantitatively with particle-in-cell simulations performed for our experimental parameters and which confirm the existence of this instability.

High-resolution inelastic x-ray scattering at the high energy density scientific instrument at the European X-Ray Free-Electron Laser.

We introduce a setup to measure high-resolution inelastic x-ray scattering at the High Energy Density scientific instrument at the European X-Ray Free-Electron Laser (XFEL). The setup uses the Si (533) reflection in a channel-cut monochromator and three spherical diced analyzer crystals in near-backscattering geometry to reach a high spectral resolution. An energy resolution of 44 meV is demonstrated for the experimental setup, close to the theoretically achievable minimum resolution. The analyzer crystals and detector are mounted on a curved-rail system, allowing quick and reliable changes in scattering angle without breaking vacuum. The entire setup is designed for operation at 10 Hz, the same repetition rate as the high-power lasers available at the instrument and the fundamental repetition rate of the European XFEL. Among other measurements, it is envisioned that this setup will allow studies of the dynamics of highly transient laser generated states of matter.

Complete temporal characterization of asymmetric pulse compression in a laser wakefield.

We present complete experimental characterization of the temporal shape of an intense ultrashort 200-TW laser pulse driving a laser wakefield. The phase of the pulse was uniquely measured by using (second-order) frequency-resolved optical gating. The pulses are asymmetrically compressed and exhibit a positive chirp consistent with the expected asymmetric self-phase-modulation due to photon acceleration or deceleration in a relativistic plasma wave. The measured pulse duration decreases linearly with increasing length and density of the plasma, in quantitative agreement with the intensity-dependent group velocity variation in the plasma wave.

Tumefactive Primary Central Nervous System Vasculitis: Imaging Findings of a Rare and Underrecognized Neuroinflammatory Disease.

Primary central nervous system vasculitis (PCNSV) is a poorly understood neuroinflammatory disease of the CNS affecting the intracranial vasculature. Although PCNSV classically manifests as a multifocal beaded narrowing of the intracranial vessels, some patients may not have angiographic abnormalities. A rare subset of patients with PCNSV present with masslike brain lesions mimicking a neoplasm. In this article, we retrospectively review 10 biopsy-confirmed cases of tumefactive PCNSV (t-PCNSV). All cases of t-PCNSV in our series that underwent CTA or MRA were found to have normal large and medium-sized vessels. T-PCNSV had a variable MR imaging appearance with most cases showing cortical/subcortical enhancing masslike lesion (70%), often with microhemorrhages (80%). Diffusion restriction was absent in all lesions. In summary, normal vascular imaging does not exclude the diagnosis of t-PCNSV. Advanced imaging techniques including MR perfusion and MR spectroscopy failed to demonstrate specific findings for t-PCNSV but assisted in excluding neoplasm in the differential diagnosis. Biopsy remains mandatory for definitive diagnosis.

An approach for the measurement of the bulk temperature of single crystal diamond using an X-ray free electron laser.

We present a method to determine the bulk temperature of a single crystal diamond sample at an X-Ray free electron laser using inelastic X-ray scattering. The experiment was performed at the high energy density instrument at the European XFEL GmbH, Germany. The technique, based on inelastic X-ray scattering and the principle of detailed balance, was demonstrated to give accurate temperature measurements, within [Formula: see text] for both room temperature diamond and heated diamond to 500 K. Here, the temperature was increased in a controlled way using a resistive heater to test theoretical predictions of the scaling of the signal with temperature. The method was tested by validating the energy of the phonon modes with previous measurements made at room temperature using inelastic X-ray scattering and neutron scattering techniques. This technique could be used to determine the bulk temperature in transient systems with a temporal resolution of 50 fs and for which accurate measurements of thermodynamic properties are vital to build accurate equation of state and transport models.

Isolated central nervous system posttransplant lymphoproliferative disorder treated with high-dose intravenous methotrexate.

Posttransplant lymphoproliferative disorder (PTLD) is an uncommon neoplastic complication of kidney transplantation, affecting about 1% of recipients. It is generally associated with Epstein-Barr virus (EBV) infection of B-lineage lymphocytes. Central nervous system (CNS) involvement is rare. There is little clinical experience with treatment of CNS PTLD due to the relative rarity of the disease other than reduction or withdrawal of immunosuppression, but it is usually fatal. We describe six patients with renal allografts and histologically proven isolated CNS PTLD. Tissue analysis from the biopsy specimens was positive for EBV material in five of the six patients. All six patients were treated with high-dose intravenous methotrexate (HD IV MTX). Methotrexate was initiated at 8 g/m2, with later adjustments for creatinine clearance. With MTX therapy, four patients have had a sustained complete response, and two had progressive disease and were referred for radiation therapy. This finding suggests a subgroup of patients may benefit from MTX but our case series is inadequate to describe overall efficacy. No unexpected toxicities were encountered in 37 courses of treatment. HD IV MTX chemotherapy should be considered as an alternative for treatment of CNS PTLD.

Necrotizing neurosarcoid: three cases with varying presentations.

BACKGROUND: Neurosarcoid affects approximately 5% of patients with sarcoidosis. A significantly more rare entity, necrotizing sarcoidosis affecting the central nervous system, has been confirmed previously in only three case reports. This paper documents three additional cases of necrotizing neurosarcoid, involving a wide spectrum of central nervous system (CNS) locations. RESULTS: One patient presented to the emergency department after being found unresponsive. The second patient was referred due to hearing loss and the third patient sought care due to weakness and numbness of his left lower extremity. Locations of involvement were diverse and included diffuse leptomeningeal involvement, a cerebellopontine angle mass and a thoracic spinal cord lesion. All patients eventually underwent surgical biopsy, and histologic review of tissue samples revealed necrotizing granulomatous inflammation. Serum ACE levels were available for two of the patients and were within normal limits. Once the diagnosis of necrotizing neurosarcoid was confirmed, all patients were treated with systemic corticosteroid therapy; one patient was also treated with an immunosuppressive agent. CONCLUSIONS: Necrotizing neurosarcoid may occur more commonly than previously described and should be considered in the differential diagnosis of patients without systemic manifestations of sarcoidosis.

Relationship of diet to root caries.

A Nutrition and Oral Health Study was conducted on 141 middle-aged and elderly adults (54% female and 46% male; aged 47-83 y, mean = 67; 51% college educated; and 89% white). This study reports on the relationship between root caries and diet. Nutritional composition was derived from two 3-d food diaries. Root caries was measured according to the 1985 Adult Survey Diagnostic Criteria of the National Institute of Dental Research. When the individuals were segregated by their root DFS (decayed and filled surfaces) status into highest (> or = 7) and lowest (< or = 1) quartiles, the sucrose consumption was significantly higher in the higher DFS group. Mean energy consumption and mean number of teeth were the same in both groups. When the individuals were segregated by sucrose consumption into highest (> or = 89 g) and lowest (< or = 31 g) quartiles, DFS root status was significantly higher (P < 0.01) in the highest quartile group (7 g) vs the lowest group (4 g). By using data from subjects with two food diaries, a stepwise-linear-regression model for root caries showed that 4.2% of the variance for root caries was explained by sucrose, 2.8% by plaque, 3.8% by total number of teeth, and 5.6% by gingival recession. These data suggest that root caries has a similar dietary etiology to coronal caries.

Dietary models for root caries.

A stepwise multiple logistic regression was computed to assess which of the nutritional variables differentiate the healthy and diseased group of participants in the Forsyth Specialized Caries Center (n = 275). Variables considered as candidates for the model included the consumption per week of sugars, starch, cheese, fruits and fruit juices, noncariogenic foods, and dairy products. Two variables--sugars and cheese--were statistically significant by the stepwise procedure. Increased intake of sugar was associated with being in the root caries group, whereas high intake of cheese was negatively associated with root caries. Thus, cheese seems to have a protective effect after sugar intake is controlled for. Odds ratios were computed to quantify the influence of the variables. An increase of two exposures of sugar per day corresponded with an odds ratio of 1.26. The odds ratio continues to increase with sugar intake so that an increase to five exposures per day gives an odds ratio of 1.79. This model is consistent with past in vitro studies suggesting that cheese protects against caries formation when sugar intake is controlled for and that increasing frequency of sugar intake increases the odds of root caries.

Thrombosis of the deep venous drainage of the brain in adults. Analysis of seven cases with review of the literature.

OBJECTIVES: To characterize the clinical, radiographic, and pathologic findings in thrombosis of the deep venous drainage of the brain. To highlight clinical and radiographic findings that may lead to the diagnosis of disease and distinguish it from dural sinus thrombosis. To review the published literature on this disorder. DESIGN: Retrospective review of the medical and radiographic records of seven patients from three institutions over the past 10 years. Review of the English language literature from 1971 to the present. RESULTS: All seven patients had risk factors for cerebral venous thrombosis. Five patients presented with a short, rapidly progressing course characterized by headache, nausea and vomiting, and decline in level of consciousness. All five patients died or were rendered severely disabled. Computed tomographic scans, magnetic resonance imaging, and magnetic resonance angiography showed findings associated with deep cerebral vein thrombosis in three of four, in five of five, and in three of three patients, respectively. Transfemoral catheter angiography was diagnostic in two of two patients. Twenty-one reported cases of deep cerebral venous thrombosis were identified in the literature. CONCLUSIONS: When the two populations are combined and compared with large series of patients with dural sinus thrombosis, patients with deep venous system thrombosis are more commonly women, tend to present with a more rapidly declining time course, altered consciousness, and long tract signs. Death or long-term sequelae are far more likely to occur in internal cerebral vein thrombosis than with dural sinus thrombosis. Unenhanced computed tomography can demonstrate findings that are strongly suggestive of the diagnosis. Magnetic resonance imaging and magnetic resonance angiography are confirmatory. Angiography may still be necessary when the diagnosis is not clear.

Leukoencephalopathy associated with cobalamin deficiency.

Patients with cobalamin deficiency may experience cognitive impairment or neuropsychiatric symptoms. Although abnormalities of central myelin are the presumed cause of these manifestations, there is a paucity of reports of white matter lesions as shown on neuroimaging studies, and the effects of cobalamin replacement on these lesions are not known. We report a man with subacute cognitive impairment associated with cobalamin deficiency and remarkable confluent white matter abnormalities on MRI, confirmed by biopsy. With cobalamin replacement, both his cognitive deficits and imaging abnormalities partially resolved. This case indicates that leukoencephalopathy, in the absence of anemia or myelopathy, should be added to the spectrum of disorders associated with cobalamin deficiency. Early detection and treatment may be associated with a greater potential for recovery.

Septicaemia due to Pasteurella pneumotropica.

The literature concerning Pasteurella pneumotropica infection in animals and man is briefly reviewed and a case presented in which the organism was the cause of septicaemia in a patient receiving chemotherapy for myeloid leukaemia. Bacteriological findings are recorded and compared with those of other authors.

A modified immunofluorescence test for Epstein-Barr virus-specific IgM antibody.

The fluorescent antibody (FA) test for Epstein-Barr virus (EBV)-specific IgM antibody was improved by the use of sodium butyrate to induce a higher level of EBV antigen expression in P3HR-1 slide preparations and by removal of rheumatoid factor (RF) and IgG antibodies from test sera by means of adsorption with suspensions of Sepharose-IgG and Streptococcus pyogenes strain AR1. This method was compared with the Paul-Bunnell test (PB) on 1106 sera submitted to a routine virus diagnostic laboratory for infectious mononucleosis serology and 96.4% of sera showed concordant results. Thus the EBV-IgM-FA method was suitable for routine diagnostic use. However, it proved helpful to test EBV-IgM positive sera by PB to assist in the detection of cross-reacting IgM antibodies sometimes present.

Spinal cord hamartoma: case report.

OBJECTIVE AND IMPORTANCE: Spinal cord hamartomas are infrequently mentioned in the literature. The authors present a unique report detailing the clinical presentation of a spinal cord hamartoma, with supporting radiographic and pathological data. CLINICAL PRESENTATION: A 26-year-old man presented with progressive right upper extremity weakness. Imaging studies revealed an exophytic cervical spinal cord mass. INTERVENTION: Open biopsy was undertaken and revealed tethering of the lesion to the dura. A pathological examination revealed a spinal cord hamartoma. CONCLUSION: The patient's symptoms improved postoperatively, suggesting that tethering of the spinal cord was responsible for the symptoms. Although unusual, hamartoma should be included in the differential diagnosis of an exophytic spinal cord lesion.

Brain edema in meningiomas is associated with increased vascular endothelial growth factor expression.

OBJECTIVE: Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF), an endothelial cell-specific cytokine, induces proliferation of endothelial cells and increases vascular permeability dramatically. All gliomas secrete significant amounts of VEGF, whereas meningiomas are variable in expression. Thus, we sought to determine whether the extent of VPF/VEGF expression in meningiomas correlated with differences in brain edema associated with these tumors. METHODS: Meningioma tissue samples from 37 patients (15 men, average age 65 +/- 13 yr; 22 women, average age 60 +/- 10 yr) who underwent surgery at or were referred to the University of Alabama Hospital were examined retrospectively for the extent of expression of immunoreactive VPF/VEGF. Additionally, peritumoral edema was assessed on a blinded basis radiographically from preoperative magnetic resonance imaging scans. Selected specimens were examined by in situ hybridization to document the source of VPF/VEGF. RESULTS: The predominant meningioma subclassifications were transitional (57%) or meningothelial (27%) subtypes. VPF/VEGF immunoreactivity ranged from 0 to 3.5, with a median value of 2 on a subjective 5-point scale; magnetic resonance imaging-assessed edema ranged in extent from 0 to 4 (subjective 5-point scale), with a median value of 2.5. The correlation of determination (R2) of magnetic resonance imaging-assessed tumor edema rating and VPF/VEGF staining intensity rating was 0.6087 (r = 0.78; P = 0.0001). In situ hybridization localized VPF/VEGF messenger ribonucleic acid in meningioma cells and not in normal parenchymal brain cells. CONCLUSION: These data suggest that meningioma-associated edema may be a result of the capacity of meningioma cells to produce VPF/VEGF locally, leading to increased tumor neovascularization and enhanced vascular permeability.

The safety of OP-1 for lumbar fusion with decompression-- a canine study.

OBJECTIVE: Bone morphogenetic proteins can serve as adjuncts to autologous bone to achieve bony fusion, and recombinant BMPs such as osteogenic protein-1 (OP-1) have the potential to replace autologous bone altogether as fusion substrate. However, relatively little is known about the safety of OP-1 for spinal fusion procedures. This study examined the effects of OP-1 intentionally placed in the subarachnoid space following thecal sac decompression, and used as graft substrate in a canine dorsolateral lumbar spine fusion model. METHODS: Lumbar decompression with dorsolateral fusion was performed on 30 canines. The dura was opened to simulate an intraoperative rent and OP-1 was placed in the subarachnoid space and in the fusion bed. Animals were sacrificed after 16 weeks and the spines were examined manually, radiographically and pathologically. RESULTS: All animals treated with OP-1 developed new bone in the subarachnoid space. This bone compressed the spinal cord, but no clinical or pathological features of neurotoxicity were noted. Mild spinal stenosis was noted at the site of dural decompression in the OP-1 treated animals. Over 80% of animals treated with OP-1 developed fusion as assessed by palpation (52% by CT criteria), while only 25% of control animals fused. CONCLUSIONS: Recombinant human OP-1 is effective at promoting fusion in a canine dorsolateral lumbar spine fusion model. However, bone growth can occur over exposed, decompressed dura, and it can form in the subdural and subarachnoid spaces. The use of OP-1 as an adjunct to spinal fusion appears to have merit, but its use must be carefully controlled to avoid unwanted bone formation and subsequent neural compression.