The ability to distinguish multiple forms of plutonium from one another, such as oxide and metal, is paramount in areas of nuclear nonproliferation and international safeguards. In its metal form, ...plutonium can be readily used in a nuclear weapon, while oxide forms are associated with nuclear reactor fuel. Oxide-based plutonium forms emit neutrons with an energy spectrum that is significantly different from the fission neutrons that are emitted from plutonium metal. Organic scintillation detectors output pulses that are proportional to the neutron energy deposited, and therefore present a means of distinguishing these plutonium forms based on their energy spectra. In this work, metal and oxide forms of plutonium were measured using a handheld detection system based on an organic glass scintillator. Monte Carlo modeling of these experiments was performed to provide insight into the origin of the features in the observed light output spectra. Through analysis of multiple regions of these spectra, in a matter of minutes we were able to unambiguously discriminate oxide and metal plutonium forms from one another and from a plutonium-beryllium neutron source, which was considered for comparison because these sources are commonly used in industrial applications. The ability to discriminate weapons-usable material from nuclear reactor fuel has applications in nuclear treaty verification and safeguards.
Abstract
Semiconductor spins are one of the few qubit realizations that remain a serious candidate for the implementation of large-scale quantum circuits. Excellent scalability is often argued for ...spin qubits defined by lithography and controlled via electrical signals, based on the success of conventional semiconductor integrated circuits. However, the wiring and interconnect requirements for quantum circuits are completely different from those for classical circuits, as individual direct current, pulsed and in some cases microwave control signals need to be routed from external sources to every qubit. This is further complicated by the requirement that these spin qubits currently operate at temperatures below 100 mK. Here, we review several strategies that are considered to address this crucial challenge in scaling quantum circuits based on electron spin qubits. Key assets of spin qubits include the potential to operate at 1 to 4 K, the high density of quantum dots or donors combined with possibilities to space them apart as needed, the extremely long-spin coherence times, and the rich options for integration with classical electronics based on the same technology.
ABSTRACT
To what extent magnetic fields affect how molecular clouds (MCs) fragment and create dense structures is an open question. We present a numerical study of cloud fragmentation using the ...SILCC-Zoom simulations. These simulations follow the self-consistent formation of MCs in a few hundred parsec-sized region of a stratified galactic disc; and include magnetic fields, self-gravity, supernova-driven turbulence, as well as a non-equilibrium chemical network. To discern the role of magnetic fields in the evolution of MCs, we study seven simulated clouds, five with magnetic fields, and two without, with a maximum resolution of 0.1 parsec. Using a dendrogram, we identify hierarchical structures, which form within the clouds. Overall, the magnetized clouds have more mass in a diffuse envelope with a number density between 1 and 100 cm−3. We find that six out of seven clouds are sheet-like on the largest scales, as also found in recent observations, and with filamentary structures embedded within, consistent with the bubble-driven MC formation mechanism. Hydrodynamic simulations tend to produce more sheet-like structures also on smaller scales, while the presence of magnetic fields promotes filament formation. Analysing cloud energetics, we find that magnetic fields are dynamically important for less dense, mostly but not exclusively atomic structures (typically up to ∼100−1000 cm−3), while the denser, potentially star-forming structures are energetically dominated by self-gravity and turbulence. In addition, we compute the magnetic surface term and demonstrate that it is generally confining, and some atomic structures are even magnetically held together. In general, magnetic fields delay the cloud evolution and fragmentation by ∼ 1 Myr.
Abstract
We present the results of smoothed particle hydrodynamic simulations investigating the evolution and fragmentation of filaments that are accreting from a turbulent medium. We show that the ...presence of turbulence and the resulting inhomogeneities in the accretion flow play a significant role in the fragmentation process. Filaments that experience a weakly turbulent accretion flow fragment in a two-tier hierarchical fashion, similar to the fragmentation pattern seen in the Orion Integral Shaped Filament. Increasing the energy in the turbulent velocity field results in more sub-structure within the filaments, and one sees a shift from gravity-dominated fragmentation to turbulence-dominated fragmentation. The sub-structure formed in the filaments is elongated and roughly parallel to the longitudinal axis of the filament, similar to the fibres seen in observations of Taurus, and suggests that the fray and fragment scenario is a possible mechanism for the production of fibres. We show that the formation of these fibre-like structures is linked to the vorticity of the velocity field inside the filament and the filament's accretion from an inhomogeneous medium. Moreover, we find that accretion is able to drive and sustain roughly sonic levels of turbulence inside the filaments, but is not able to prevent radial collapse once the filaments become supercritical. However, the supercritical filaments that contain fibre-like structures do not collapse radially, suggesting that fibrous filaments may not necessarily become radially unstable once they reach the critical line-density.
There is an urgent need for new, better instrumentation and techniques for detecting and characterizing special nuclear material (SNM), i.e., highly enriched uranium and plutonium. The development of ...improved instruments and techniques requires experiments performed with the SNM itself, which is of limited availability. This paper describes the findings of experiments performed at the National Criticality Experiments Research Center conducted using new instruments and techniques on unclassified, kg-quantity SNM objects. These experiments, performed in the framework of the Department of Energy, National Nuclear Security Administration Consortium for Monitoring, Technology, and Verification, focused on detecting, characterizing, and localizing SNM samples with masses ranging from 3.3 to 13.8 kg, including plutonium and highly enriched uranium using prototype detectors and techniques. The work demonstrates SNM detection and characterization using recently-developed prototype detection systems. Specifically, we present new results in passive detection and imaging of plutonium and uranium objects using gamma-ray and dual particle (fast neutron and gamma-ray) imaging. We also present a new analysis of the delayed neutron emissions during active interrogation of uranium using a neutron generator.
We report updated overall survival (OS) data from study NO16966, which compared capecitabine plus oxaliplatin (XELOX) vs 5-fluorouracil/folinic acid plus oxaliplatin (FOLFOX4) as first-line therapy ...in metastatic colorectal cancer.
NO16966 was a randomised, two-arm, non-inferiority, phase III comparison of XELOX vs FOLFOX4, which was subsequently amended to a 2 × 2 factorial design with further randomisation to bevacizumab or placebo. A planned follow-up exploratory analysis of OS was performed.
The intent-to-treat (ITT) population comprised 2034 patients (two-arm portion, n=634; 2 × 2 factorial portion, n=1400). For the whole NO16966 study population, median OS was 19.8 months in the pooled XELOX/XELOX-placebo/XELOX-bevacizumab arms vs 19.5 months in the pooled FOLFOX4/FOLFOX4-placebo/FOLFOX4-bevacizumab arms (hazard ratio 0.95 (97.5% CI 0.85-1.06)). In the pooled XELOX/XELOX-placebo arms, median OS was 19.0 vs 18.9 months in the pooled FOLFOX4/FOLFOX4-placebo arms (hazard ratio 0.95 (97.5% CI 0.83-1.09)). FOLFOX4 was associated with more grade 3/4 neutropenia/granulocytopenia and febrile neutropenia than XELOX, and XELOX with more grade 3 diarrhoea and grade 3 hand-foot syndrome than FOLFOX4.
Updated survival data from study NO16966 show that XELOX is similar to FOLFOX4, confirming the primary analysis of progression-free survival. XELOX can be considered as a routine first-line treatment option for patients with metastatic colorectal cancer.
Background: The design and analysis of protective systems requires a detailed understanding of, and the ability to accurately predict, the distribution of pressure loads acting on an obstacle ...following an explosive detonation. In particular, there is a pressing need for accurate characterisation of blast loads in the region very close to a detonation, where even small improvised devices can produce serious structural or material damage. Objective: Accurate experimental measurement of these near-field blast events, using intrusive methods, is demanding owing to the high magnitudes (> 100 MPa) and short durations (< 1 ms) of loading. The objective of this article is to develop a non-intrusive method for measuring reflected blast pressure distributions using image analysis. Methods: This article presents results from high speed video analysis of near-field spherical PE4 explosive blasts. The Canny edge detection algorithm is used to track the outer surface of the explosive fireball, with the results used to derive a velocity-radius relationship. Reflected pressure distributions are calculated using this velocity-radius relationship in conjunction with the Rankine-Hugoniot jump conditions. Results: The indirectly measured pressure distributions from high speed video are compared with directly measured pressure distributions and are shown to be in good qualitative agreement with respect to distribution of reflected pressures, and in good quantitative agreement with peak reflected pressures (within 10% of the maximum recorded value). Conclusions: The results indicate that it is possible to accurately measure blast loads in the order of 100s MPa using techniques which do not require sensitive recording equipment to be located close to the source of the explosion.
The link between chronic inflammation and increased risk of developing some cancers is well established. The molecular mechanisms that underlie this process (cause) as well as the chronic ...inflammation that accompanies cancer (consequence) continue to be elucidated. Cancer‐associated inflammation has effects on the ability of cancers to metastasize, on the clinical manifestations of cancer, and on the ability of the patient to tolerate anticancer therapy. The identification of biomarkers of cancer‐associated inflammation will assist in identifying patients at risk of its consequences.
Clinical Pharmacology & Therapeutics (2010) 87 4, 504–508. doi:10.1038/clpt.2009.254
Background
The role of inhaled corticosteroids (ICS) in chronic obstructive pulmonary disease (COPD) has been the subject of much controversy. Major international guidelines recommend selective use ...of ICS. Recently published meta‐analyses have reported conflicting findings on the effects of inhaled steroid therapy in COPD.
Objectives
To determine the efficacy and safety of inhaled corticosteroids in stable patients with COPD, in terms of objective and subjective outcomes.
Search methods
A pre‐defined search strategy was used to search the Cochrane Airways Group Specialised Register for relevant literature. Searches are current as of July 2011.
Selection criteria
We included randomised trials comparing any dose of any type of inhaled steroid with a placebo control in patients with COPD. Acute bronchodilator reversibility to short‐term beta2‐agonists and bronchial hyper‐responsiveness were not exclusion criteria. The a priori primary outcome was change in lung function. We also analysed data on mortality, exacerbations, quality of life and symptoms, rescue bronchodilator use, exercise capacity, biomarkers and safety.
Data collection and analysis
Two review authors independently assessed trial quality and extracted data. We contacted study authors for additional information. We collected adverse effects information from the trials.
Main results
Fifty‐five primary studies with 16,154 participants met the inclusion criteria. Long‐term use of ICS (more than six months) did not consistently reduce the rate of decline in forced expiratory volume in one second (FEV1) in COPD patients (generic inverse variance analysis: mean difference (MD) 5.80 mL/year with ICS over placebo, 95% confidence interval (CI) ‐0.28 to 11.88, 2333 participants; pooled means analysis: 6.88 mL/year, 95% CI 1.80 to 11.96, 4823 participants), although one major trial demonstrated a statistically significant difference. There was no statistically significant effect on mortality in COPD patients (odds ratio (OR) 0.98, 95% CI 0.83 to 1.16, 8390 participants). Long‐term use of ICS reduced the mean rate of exacerbations in those studies where pooling of data was possible (generic inverse variance analysis: MD ‐0.26 exacerbations per patient per year, 95% CI ‐0.37 to ‐0.14, 2586 participants; pooled means analysis: MD ‐0.19 exacerbations per patient per year, 95% CI ‐0.30 to ‐0.08, 2253 participants). ICS slowed the rate of decline in quality of life, as measured by the St George's Respiratory Questionnaire (MD ‐1.22 units/year, 95% CI ‐1.83 to ‐0.60, 2507 participants). Response to ICS was not predicted by oral steroid response, bronchodilator reversibility or bronchial hyper‐responsiveness in COPD patients. There was an increased risk of oropharyngeal candidiasis (OR 2.65, 95% CI 2.03 to 3.46, 5586 participants) and hoarseness. In the long‐term studies, the rate of pneumonia was increased in the ICS group compared to placebo, in studies that reported pneumonia as an adverse event (OR 1.56, 95% CI 1.30 to 1.86, 6235 participants). The long‐term studies that measured bone effects generally showed no major effect on fractures and bone mineral density over three years.
Authors' conclusions
Patients and clinicians should balance the potential benefits of inhaled steroids in COPD (reduced rate of exacerbations, reduced rate of decline in quality of life and possibly reduced rate of decline in FEV1) against the potential side effects (oropharyngeal candidiasis and hoarseness, and risk of pneumonia).
Cognitive impairment and fatigue have been associated with cancer and its treatment. We present baseline data from a large longitudinal study that evaluates cognitive function, fatigue, and potential ...underlying mechanisms following diagnosis of colorectal cancer (CRC).
We evaluated CRC patients with stage I–III disease before or after surgery, participants with limited metastatic disease and healthy controls (HC). Neuropsychological evaluation included clinical and computerised tests. Participants completed questionnaires for fatigue and quality of life (QOL)-(FACT-F), anxiety/depression, and cognitive symptoms (FACT-Cog). Ten cytokines, clotting factors, sex hormones, carcinoembryonic antigen (CEA), and apolipoprotein E genotype were evaluated. Primary end points were cognitive function on clinical tests evaluated by a Global Deficit score (GDS) and fatigue. Associations between test results, demographic, and disease related factors were explored.
We assessed 291 participants with early-stage disease median age 59 (23–75) years, 63% men, 72 with metastatic disease, and 72 HC. Using GDS, 45% (126/281) of participants with early-stage CRC had cognitive impairment versus 15% (11/72) of HC (odds ratio 4.51, 95% confidence interval 2.28–8.93; P < 0.001), with complex processing speed, attention/working memory, and verbal learning efficiency being most affected. Women with early-stage CRC had greater cognitive impairment than men 55/105 (52%) versus 71/176 (40%), P < 0.050. Cognitive symptoms were self-reported by 21% (59/286) of early-stage patients versus 17% (12/72) of HC; fatigue by 52% (149/287) of early-stage patients and 26% (19/72) of HC (P < 0.0001). Women reported more fatigue than men (P = 0.003). Fatigue, QOL, anxiety/depression, and cognitive symptoms were associated with each other (r = 0.43–0.71), but not with neuropsychological performance. Most cytokines were elevated in cancer patients. Cognitive function was not associated with cytokines, sex hormones, clotting factors, CEA, or apolipoprotein E genotype.
The incidence of cognitive impairment was three to five times higher in CRC patients than HC, with women having higher impairment rates than men. The cognitive impairment profile suggests dysfunction primarily in fronto-subcortical brain systems.
NCT00188331.
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