Simple atomic quantum memory suitable for semiconductor quantum dot single photons

Quantum memories matched to single photon sources will form an important cornerstone of future quantum network technology. We demonstrate such a memory in warm Rb vapor with on-demand storage and retrieval, based on electromagnetically induced transparency. With an acceptance bandwidth of $\delta f$ = 0.66~GHz the memory is suitable for single photons emitted by semiconductor quantum dots. In this regime, vapor cell memories offer an excellent compromise between storage efficiency, storage time, noise level, and experimental complexity, and atomic collisions have negligible influence on the optical coherences. Operation of the memory is demonstrated using attenuated laser pulses on the single photon level. For 50 ns storage time we measure $\eta_{\textrm{e2e}}^{\textrm{50ns}} = 3.4(3)\%$ \emph{end-to-end efficiency} of the fiber-coupled memory, with an \emph{total intrinsic efficiency} $\eta_{\textrm{int}} = 17(3)\%$. Straightforward technological improvements can boost the end-to-end-efficiency to $\eta_{\textrm{e2e}} \approx 35\%$; beyond that increasing the optical depth and exploiting the Zeeman substructure of the atoms will allow such a memory to approach near unity efficiency. In the present memory, the unconditional readout noise level of $9\cdot 10^{-3}$ photons is dominated by atomic fluorescence, and for input pulses containing on average $\mu_{1}=0.27(4)$ photons the signal to noise level would be unity

The Neural Basis of Predicting the Outcomes of Imagined Actions

A key feature of human intelligence is the ability to predict the outcomes of one’s own actions prior to executing them. Action values are thought to be represented in part in the dorsal and ventral medial prefrontal cortex (mPFC), yet current studies have focused on the value of executed actions rather than the anticipated value of a planned action. Thus, little is known about the neural basis of how individuals think (or fail to think) about their actions and the potential consequences before they act. We scanned individuals with fMRI while they thought about performing actions that they knew would likely be rewarded or unrewarded. Here we show that merely imagining an unrewarded action, as opposed to imagining a rewarded action, increases activity in the dorsal anterior cingulate cortex, independently of subsequent actions. This activity overlaps with regions that respond to actual unrewarded actions. The findings show a distinct network that signals the prospective outcomes of one’s possible actions. A number of clinical disorders such as schizophrenia and drug abuse involve a failure to take the potential consequences of an action into account prior to acting. Our results thus suggest how dysfunctions of the mPFC may contribute to such failures

On the midwater fish faunas of Gulf Stream rings with respect to habitat differences between slope water and northern Sargasso Sea

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Woods Hole Oceanographic Institution Apri, 1976.Appendix C, Biographical notes, not included.Forty-three 1000-in oblique Isaacs-Kidd midwater trawl collections were made on six cruises. In most cases, these were accompanied by 1500-m hydrocasts and plankton tows to 800 m. The fish collections comprise 19,400 specimens in 129 species, from Slope Water, Gulf Stream, Northern Sargasso Sea, and four cold-core rings. Temperature, salininty, oxygen, phosphate, and zooplankton biomass information accompany the collections. A model predicts that expatriate populations of Caribbean species can be maintained in the Slope Water and Northern Sargasso Sea in excess of 15 per cent of their Caribbean population density. With Caribbean contamination accounted for, the relative abundances of species in Slope Water and Northern Sargasso Sea are used to assign habitat preferences. Species clusters derived from an ordination using correspondence ana1ysis agree well with the habitat preference groups. The assemblage of species in the rings occupies the middle of a gradient in faunal composition from winter conditions in Slope Water to fall conditions in the Northern Sargasso Sea. The midwater habitat is modeled as two layers, and the ring environment as a hybrid habitat consisting of a surface layer of Northern Sargasso Sea habitat and a deep layer of Slope Water habitat. This model is consistent with patterns of species abundance. It is argued that the dramatic change in the depth of the main thermocline on crossing the Gulf Stream is the major physical factor affecting fish distributions with respect to this boundary.Dissertation work was supported by the Woods Hole Oceanographic Instution, the Jesse-Smith Noyes Foundation, and the National Science Foundation, Doctoral Dissertation Improvement Grant GA 38003

Koopman Operator for Nonlinear Flight Dynamics

Dynamical systems representing vehicle flight are inherently nonlinear. Currently there are no generalised frameworks for explicit characterisation and solution of such systems. Conversely, linear systems are well understood, and many efficient algorithms are available for explicit characterisation and prediction. Koopman operator theory presents a framework for constructing finite linear approximations to nonlinear systems, by projecting the nonlinear dynamics onto a Hilbert space constructed of Koopman operator eigenfunctions. This work summarises the theory underpinning the Galerkin method of constructing Koopman linear approximations of known dynamics using polynomial basis functions. Details of a system-agnostic program for computing the Koopman linear matrix is presented. Linear approximations are constructed for two nonlinear systems: a simple Duffing oscillator, and a three degree-of-freedom glider trajectory. The ability of linear systems to closely follow the time-integrated nonlinear solution is demonstrated. Furthermore, expansions of the lifted linear model to incorporate variable system parameter, to incorporate bilinear time-varying inputs necessary for optimal control calculations, as well as methods to avoid the inherent linear system limitations are explored. This work demonstrates feasibility and merit of the lifted linear system approach for analysis of vehicle dynamics and trajectory problems

Bimodal release ondansetron for acute gastroenteritis among adolescents and adults: A randomized clinical trial

Importance: Vomiting resulting from acute gastroenteritis is commonly treated with intravenous antiemetics in acute care settings. If oral treatment were beneficial, patients might not need intravenous administered hydration or medication. Furthermore, a long-acting treatment could provide sustained relief from nausea and vomiting. Objective: To determine whether an experimental long-acting bimodal release ondansetron tablet decreases gastroenteritis-related vomiting and eliminates the need for intravenous therapy for 24 hours after administration. Design, Setting, and Participants: This placebo-controlled, double-blind, randomized clinical trial included patients from 19 emergency departments and 2 urgent care centers in the United States from December 8, 2014, to February 17, 2017. Patients 12 years and older with at least 2 vomiting episodes from presumed gastroenteritis in the previous 4 hours and symptoms with less than 36 hours\u27 duration were randomized using a 3:2 active to placebo ratio. Analyses were performed on an intent-to-treat basis and conducted from June 1, 2017, to November 1, 2017. Intervention: Bimodal release ondansetron tablet containing 6 mg of immediate release ondansetron and 18 mg of a 24-hour release matrix for a total of 24 mg of ondansetron. Main Outcomes and Measures: Treatment success was defined as no further vomiting, no need for rescue medication, and no intravenous hydration for 24 hours after bimodal release ondansetron administration. Results: Analysis included 321 patients (mean [SD] age, 29.0 [11.1] years; 195 [60.7%] women), with 192 patients in the bimodal release ondansetron group and 129 patients in the placebo group. Treatment successes were observed in 126 patients in the bimodal release ondansetron group (65.6%) compared with 70 patients in the placebo group (54.3%), with an 11.4% (95% CI, 0.3%-22.4%) absolute probability difference. The proportion of treatment success was 21% higher among patients who received bimodal release ondansetron compared with those who received a placebo (relative risk, 1.21; 95% CI, 1.00-1.46; P = .04). In an analysis including only patients with a discharge diagnosis of acute gastroenteritis and no major protocol violations, there were 123 treatment successes (69.5%) in the bimodal release ondansetron group compared with 67 treatment successes (54.9%) in the placebo group (relative risk, 1.27; 95% CI, 1.05-1.53; P = .01). Adverse effects were infrequent and similar to the known safety profile of ondansetron. Conclusions and Relevance: This randomized clinical trial found that a long-acting bimodal release oral ondansetron tablet was an effective antiemetic among adolescents and adults with moderate to severe vomiting from acute gastroenteritis. The drug benefits extended to 24 hours after administration. Bimodal release ondansetron may decrease the need for intravenous access and emergency department care to manage acute gastroenteritis. Trial Registration: ClinicalTrials.gov identifier: NCT02246439

catena-Poly[copper(II)-bis­(μ-2-ethyl-5-methyl­imidazole-4-sulfonato-κ3 N 3,O 4:O 4′)]

In the title compound, [Cu(C6H9N2O3S)2]n, the copper(II) ion sits on an inversion center and is chelated by the imidazole N and sulfonate O atoms of two ligands in equatorial positions. O atoms of adjacent mol­ecules coordinate in the axial positions. Jahn–Teller tetra­gonal distortion is evident in the coordination geometry [Cu—N and Cu—O equatorial distances of 1.971 (3) and 2.045 (2) Å, respectively, with a Cu—O axial distance of 2.433 (3) Å]. The structure is propagated by an infinite chain of eight-membered (Cu—O—S—O)2 ring systems along the a axis. Only N—H⋯O hydrogen bonding exists between the chains

Treatment outcomes of patients on Second-line Antiretroviral Therapy in resource-limited settings: A Systematic Review and Meta-Analysis

A growing proportion of patients on antiretroviral therapy in resource-limited settings have switched to second-line regimens. We carried out a systematic review in order to summarize reported rates and reasons for virological failure among people on second-line therapy in resource-limited settings

Statistical tests for intra-tumour clonal co-occurrence and exclusivity

Tumour progression is an evolutionary process in which different clones evolve over time, leading to intra-tumour heterogeneity. Interactions between clones can affect tumour evolution and hence disease progression and treatment outcome. Intra-tumoural pairs of mutations that are overrepresented in a co-occurring or clonally exclusive fashion over a cohort of patient samples may be suggestive of a synergistic effect between the different clones carrying these mutations. We therefore developed a novel statistical testing framework, called GeneAccord, to identify such gene pairs that are altered in distinct subclones of the same tumour. We analysed our framework for calibration and power. By comparing its performance to baseline methods, we demonstrate that to control type I errors, it is essential to account for the evolutionary dependencies among clones. In applying GeneAccord to the single-cell sequencing of a cohort of 123 acute myeloid leukaemia patients, we find 1 clonally co-occurring and 8 clonally exclusive gene pairs. The clonally exclusive pairs mostly involve genes of the key signalling pathways

Critical international relations and the impact agenda

How should critical International Relations (IR) scholars approach the ‘impact agenda’? While most have been quite resistant to it, I argue in this essay that critical IR should instead embrace the challenge of impact – and that both IR as a field and the impact agenda more broadly would gain greatly from it doing so. I make this case through three steps. I show, firstly, that critical IR has till now been very much at the impact agenda’s margins, and that this situation contrasts strikingly with its well-established importance within IR teaching and research. I argue, secondly, that critical IR scholars both could and should do more impact work – that the current political conjuncture demands it, that many of the standard objections to doing so are misplaced, and indeed that ‘critical’ modes of research are in some regards better suited than ‘problem-solving’ ones to generating meaningful change – and offer a series of recommended principles for undertaking critically-oriented impact and engagement work. But I also argue, thirdly, that critical social science holds important lessons for the impact agenda, and that future impact assessments need to take these lessons on board – especially if critical IR scholarship is to embrace impact more fully. Critical IR, I submit, should embrace impact; but at the same time, research councils and assessments could do with modifying their approach to it, including by embracing a more critical and political understanding of what impact is and how it is achieved