Generation of frequency sidebands on single photons with indistinguishability from quantum dots

Generation and manipulation of the quantum state of a single photon is at the heart of many quantum information protocols. There has been growing interest in using phase modulators as quantum optics devices that preserve coherence. In this Letter, we have used an electro-optic phase modulator to shape the state vector of single photons emitted by a quantum dot to generate new frequency components (modes) and explicitly demonstrate that the phase modulation process agrees with the theoretical prediction at a single photon level. Through two-photon interference measurements we show that for an output consisting of three modes (the original mode and two sidebands), the indistinguishability of the mode engineered photon, measured through the secondorder intensity correlation (g2(0)) is preserved. This work demonstrates a robust means to generate a photonic qubit or more complex state (e.g., a qutrit) for quantum communication applications by encoding information in the sidebands without the loss of coherence

Soros, Child Sacrifices, and {5G}: {U}nderstanding the Spread of Conspiracy Theories on {Web} Communities

This paper presents a multi-platform computational pipeline geared to identify social media posts discussing (known) conspiracy theories. We use 189 conspiracy claims collected by Snopes, and find 66k posts and 277k comments on Reddit, and 379k tweets discussing them. Then, we study how conspiracies are discussed on different Web communities and which ones are particularly influential in driving the discussion about them. Our analysis sheds light on how conspiracy theories are discussed and spread online, while highlighting multiple challenges in mitigating them

Stellar Kinematics and Structural Properties of Virgo Cluster Dwarf Early-Type Galaxies from the SMAKCED Project. I. Kinematically Decoupled Cores and Implications for Infallen Groups in Clusters

We present evidence for kinematically decoupled cores (KDCs) in two dwarf early-type (dE) galaxies in the Virgo cluster, VCC 1183 and VCC 1453, studied as part of the SMAKCED stellar absorption-line spectroscopy and imaging survey. These KDCs have radii of 1.8'' (0.14 kpc) and 4.2'' (0.33 kpc), respectively. Each of these KDCs is distinct from the main body of its host galaxy in two ways: (1) inverted sense of rotation; and (2) younger (and possibly more metal-rich) stellar population. The observed stellar population differences are probably associated with the KDC, although we cannot rule out the possibility of intrinsic radial gradients in the host galaxy. We describe a statistical analysis method to detect, quantify the significance of, and characterize KDCs in long-slit rotation curve data. We apply this method to the two dE galaxies presented in this paper and to five other dEs for which KDCs have been reported in the literature. Among these seven dEs, there are four significant KDC detections, two marginal KDC detections, and one dE with an unusual central kinematic anomaly that may be an asymmetric KDC.The frequency of occurence of KDCs and their properties provide important constraints on the formation history of their host galaxies. We discuss different formation scenarios for these KDCs in cluster environments and find that dwarf-dwarf wet mergers or gas accretion can explain the properties of these KDCs. Both of these mechanisms require that the progenitor had a close companion with a low relative velocity. This suggests that KDCs were formed in galaxy pairs residing in a poor group environment or in isolation whose subsequent infall into the cluster quenched star formation.Comment: 14 pages, accepted for publication in Ap

Towards active utilisation of community forestry: silvo-institutional model for sustainable forest management in Nepal

This paper explains what we term the ‘silvo-institutional model’ for a more productive, sustainable and equitable management of community forests in Nepal. The paper draws on four years of action research in six research sites of Kavre and Lamjung districts, complemented by the review of silviculture-based forest management by Government of Nepal in various parts of the country. The findings indicate that first, early silviculture-based forest management initiatives have failed because they did not adequately consider the policy and institutional dimensions. Second, current initiatives, while looked promising for the active utilisation of community forests, have faced with complex regulatory and institutional barriers. We argue that a new ‘silvoinstitutional model’, which combines technological and institutional dimensions, has a potential to increase the prospect of successful implementation of silviculture-based forest management.N. S. Paudel, H. Ojha, K. Shrestha, E. Cedamon, R. Karki, G. Paudel, M. Basyal, I. Nuberg and S. Danga

The double pendulum

Policy discourses posit an accountability deficit as an underlying cause of a “learning crisis” in many low-income countries. Many studies understand this perceived deficit from a principal-agent perspective, arguing that incentives facing teachers and schools often do not align to the interests of parents and students. Such perspectives underlie many randomized controlled trials, which associate interventions with outcomes, but which also produce varying or inconsistent results across contexts. This paper seeks to study the accountability of schools and teachers more directly, looking at how it varies across public and private schools and how it relates to students’ literacy and numeracy abilities. We report results from a mixed methods study conducted in Mumbai and Kathmandu. Our results show that there are some relationships between accountability and learning outcomes, but these appear to be specific to the context. Quantitative data also show that differences between public and private models of schooling are negligible when students’ social backgrounds and school composition are considered. Qualitative data show that accountability processes create a significant burden on staff time and embed complex power dynamics that are not always productive. Taken together, these results problematize policies that seek to improve learning through “demand-side” approaches such as privatization. They show that the dynamics of accountability are a complex system, like the motion of a “double pendulum,” and therefore simple conceptual approaches such as the principal-agent model are of limited academic and practical utility

Prevalence Study of H. pylori infection in Dyspeptic patients coming to Nepal Medical College Teaching Hospital, Jorpati, Kathmandu

ABSTRACT Helicobacter pylori (H. pylori) is one of the most common human infections worldwide particularly in the developing countries. It has been established as etiology of chronic gastritis and peptic ulcer disease, gastric adenocarcinoma and mucosal associated lymphoid tissue lymphoma (MALT). During this decade, there have been some reports showing a decline in global prevalence of H. pylori infection and peptic diseases including many Asian countries. Hence to determine prevalence of Helicobacter pylori infection in dyspeptic patients, this descriptive, non-interventional study was carried out at the Endoscopy sub-unit of the Surgery Department from April 2011 to February 2012. Three hundred nineteen dyspeptic patients (Male 161 and female 152) with a mean age of 20.12 years were examined for the presence of H. pylori infection by histology staining. The prevalence of H. pylori infection was 50.47%. The most common endoscopic fi ndings was gastritis (47.6%) followed by normal fi ndings 57 (17.87%). A total of 8.47% of gastric Ulcer, oesophagitis 5.64% and gastric cancer 0.94% were detected. All three cases of gastric cancer were positive for H. pylori infection. Among gastritis, H. pylori was observed in 67 (44%) cases and 18 out of 57 (5.6 %) of normal gastric mucosa showed H. pylori. The endoscopic fi ndings such as gastritis, gastric ulcer, duodenal ulcer and gastro duodenal refl ux are signifi cantly associated with H pyloric infection. The prevalence of H. pylori infection is still high in peptic diseases. H pylori infection is signifi cantly correlated with peptic ulcer diseases than with non-ulcer dyspepsia. Further studies are required to establish the H. pylori positive cases with that of other tests such as serological detection of anti H. pylori antibody by ELISA/ICT and culture to establish a diagnosis quickly without any invasive method and institute proper management thus reducing morbidity

Value chain analysis of non-timber forest products in Baglung district, Nepal

This study was carried out in five Village Development Committees of Baglung district, Nepal. The main objective was to assess the constraints and opportunities to run the non-timber forest products based enterprises, and to design business solutions to make their value chains more efficient and competitive with the best utilization of the available resources. Primary data were collected through group discussions, key informants interview, informal meetings and direct observations, using open-ended questionnaires and checklists. Similarly, secondary data were gathered from reports and records of community forest user groups, District Forest Office and other organizations. The data were analyzed using qualitative and quantitative tools. The identified major constraints concerning the selected value chains are: absence of detailed resource inventory; inadequate knowledge and skills with local people about modern technology and product quality parameters, local resource management policy and sustainable resource harvesting; insufficient finance with local processors; lack of sufficient information about market; and poor infrastructure development. In addition, the study also identified a number of opportunities such as the resource potential and monetary benefits to the local people; financial access through community forest user groups' fund and financial institutions; growing market demand for quality products; involvement of service providers in forest resource management; and supportive policy for employment generation from locally available natural resources. This paper has suggested some business solutions for the effective value chain of selected products

Strain-driven disproportionation at a correlated oxide metal-insulator transition

Metal-to-insulator phase transitions in complex oxide thin films are exciting phenomena which may be useful for device applications, but in many cases the physical mechanism responsible for the transition is not fully understood. Here we demonstrate that epitaxial strain generates local disproportionation of the NiO6 octahedra, driven through changes in the oxygen stoichiometry, and that this directly modifies the metal-to-insulator phase transition in epitaxial (001) NdNiO3 thin films. Theoretically, we predict that the Ni-O-Ni bond angle decreases, while octahedral tilt and local disproportionation of the NiO6 octahedra increases resulting in a small band gap in an otherwise metallic system. This is driven by an increase in oxygen vacancy concentration in the rare-earth nickelates with increasing in-plane biaxial tensile strain. Experimentally, we find an increase in pseudocubic unit-cell volume and resistivity with increasing biaxial tensile strain, corroborating our theoretical predictions. With electron-energy-loss spectroscopy and x-ray absorption, we find a reduction of the Ni valence with increasing tensile strain. These results indicate that epitaxial strain modifies the oxygen stoichiometry of rare-earth perovskite thin films and through this mechanism affects the metal-to-insulator phase transition in these compounds