Constraint-based Wavevector- and Frequency-dependent Exchange-Correlation Kernel of the Uniform Electron Gas

According to time-dependent density functional theory, the exact exchange-correlation kernel f$_{xc}$(n, q, $\omega$) determines not only the ground-state energy but also the excited-state energies/lifetimes and time-dependent linear density response of an electron gas of uniform density n $=$ 3/(4$\pi$r$^3_s$). Here we propose a parametrization of this function based upon the satisfaction of exact constraints. For the static ($\omega$ = 0) limit, we modify the model of Constantin and Pitarke at small wavevector q to recover the known second-order gradient expansion, plus other changes. For all frequencies $\omega$ at q $=$ 0, we use the model of Gross, Kohn, and Iwamoto. A Cauchy integral extends this model to complex $\omega$ and implies the standard Kramers-Kronig relations. A scaling relation permits closed forms for not only the imaginary but also the real part of f$_{xc}$ for real $\omega$. We then combine these ingredients by damping out the $\omega$ dependence at large q in the same way that the q dependence is damped. Away from q $=$ 0 and $\omega$ $=$ 0, the correlation contribution to the kernel becomes dominant over exchange, even at r$_s$ $=$ 4, the valence electron density of metallic sodium. The resulting correlation energy from integration over imaginary $\omega$ is essentially exact. The plasmon pole of the density response function is found by analytic continuation of f$_{xc}$ to $\omega$ just below the real axis, and the resulting plasmon lifetime first decreases from infinity and then increases as q grows from 0 toward the electron-hole continuum. A static charge-density wave is found for r$_s$ $>$ 69, and shown to be associated with softening of the plasmon mode. The exchange-only version of our static kernel confirms Overhauser's 1968 prediction that correlation enhances the charge-density wave.Comment: 20 pages including 11 figure

Transcriptome Profiling of Interaction Effects of Soybean Cyst Nematodes and Soybean Aphids on Soybean

Soybean aphid (Aphis glycines; SBA) and soybean cyst nematode (Heterodera glycines; SCN) are two major pests of soybean (Glycine max) in the United States of America. This study aims to characterize three-way interactions among soybean, SBA, and SCN using both demographic and genetic datasets. SCN-resistant and SCN-susceptible soybean cultivars with a combination of soybean aphids (biotype 1) and SCN (HG type 0) in a randomized complete block design (RCBD) with six blocks were used to evaluate the three-way interactions in a greenhouse setup. Treatments receiving SCN were infested at planting with 2000 nematode eggs, and the treatments with soybean aphids were infested at second trifoliate growth stage (V2) with 15 soybean aphids. The whole roots were sampled from plants at 5 and 30 days post SBA infestation for RNA sequencing using Illumina Hiseq. 3000. The data comprises of 47 libraries that are useful for further analyses of important genes, which are involved in interaction effects of SBA and SCN on soybean

Graphene supported plasmonic photocatalyst for hydrogen evolution in photocatalytic water splitting

It is well known that the noble metal nanoparticles show active absorption in the visible region because of the existence of the unique feature known as surface plasmon resonance (SPR). Here we report the effect of plasmonic Au nanoparticles on the enhancement of the renewable hydrogen (H2) evolution through photocatalytic water splitting. The plasmonic Au/graphene/TiO2 photocatalyst was synthesized in two steps: first the graphene/TiO2 nanocomposites were developed by the hydrothermal decomposition process; then the Au was loaded by photodeposition. The plasmonic Au and the graphene as co-catalyst effectively prolong the recombination of the photogenerated charges. This plasmonic photocatalyst displayed enhanced photocatalytic H2 evolution for water splitting in the presence of methanol as a sacrificial reagent. The H2 evolution rate from the Au/graphene co-catalyst was about 9 times higher than that of a pure graphene catalyst. The optimal graphene content was found to be 1.0 wt %, giving a H2 evolution of 1.34 mmol (i.e., 26 μmolhˉ¹), which exceeded the value of 0.56 mmol (i.e., 112 μmolhˉ¹) observed in pure TiO2. This high photocatalytic H2 evolution activity results from the deposition of TiO2 on graphene sheets, which act as an electron acceptors to efficiently separate the photogenerated charge carriers. However, the Au loading enhanced the H2 evolution dramatically and achieved a maximum value of 12 mmol (i.e., 2.4 mmolhˉ¹) with optimal loading of 2.0 wt% Au on graphene/TiO2 composites. The enhancement of H2 evolution in the presence of Au results from the SPR effect induced by visible light irradiation, which boosts the energy intensity of the trapped electron as well as active sites for photocatalytic activity

Magnetic skyrmion bubble motion driven by surface acoustic waves

We study the dynamical control of a magnetic skyrmion bubble by using counter-propagating surface acoustic waves (SAWs) in a ferromagnet. First, we determine the bubble mass and derive the force due to SAWs acting on a magnetic bubble using Thiele\u27s method. The force that pushes the bubble is proportional to the strain gradient for the major strain component. We then study the dynamical pinning and motion of magnetic bubbles by SAWs in a nanowire. In a disk geometry, we propose a SAWs-driven skyrmion bubble oscillator with two resonant frequencies

Understanding Greenhouse Gases

Students will conduct hands-on experiments to see how greenhouse gases interact with the Earth’s atmosphere and how greenhouse gases affect temperature. This lesson introduces National Geographic’s Geo-Inquiry Process, where students will identify a Geo-inquiry question, collect data, and create a project around the answer to their question. Students will then present their findings to their peers and evaluate their Geo-Inquiry process

Local Differential Privacy for Federated Learning

Advanced adversarial attacks such as membership inference and model memorization can make federated learning (FL) vulnerable and potentially leak sensitive private data. Local differentially private (LDP) approaches are gaining more popularity due to stronger privacy notions and native support for data distribution compared to other differentially private (DP) solutions. However, DP approaches assume that the FL server (that aggregates the models) is honest (run the FL protocol honestly) or semi-honest (run the FL protocol honestly while also trying to learn as much information as possible). These assumptions make such approaches unrealistic and unreliable for real-world settings. Besides, in real-world industrial environments (e.g., healthcare), the distributed entities (e.g., hospitals) are already composed of locally running machine learning models (this setting is also referred to as the cross-silo setting). Existing approaches do not provide a scalable mechanism for privacy-preserving FL to be utilized under such settings, potentially with untrusted parties. This paper proposes a new local differentially private FL (named LDPFL) protocol for industrial settings. LDPFL can run in industrial settings with untrusted entities while enforcing stronger privacy guarantees than existing approaches. LDPFL shows high FL model performance (up to 98%) under small privacy budgets (e.g., epsilon = 0.5) in comparison to existing methods.Comment: 17 page

Overcoming the challenges facing Nepal's health system during federalisation: an analysis of health system building blocks.

Nepal's move to a federal system was a major constitutional and political change, with significant devolution of power and resources from the central government to seven newly created provinces and 753 local governments. Nepal's health system is in the process of adapting to federalism, which is a challenging, yet potentially rewarding, task. This research is a part of broader study that aims to explore the opportunities and challenges facing Nepal's health system as it adapts to federalisation. This exploratory qualitative study was conducted across the three tiers of government (federal, provincial, and local) in Nepal. We employed two methods: key informant interviews and participatory policy analysis workshops, to offer an in-depth understanding of stakeholders' practical learnings, experiences, and opinions. Participants included policymakers, health service providers, local elected members, and other local stakeholders. All interviews were audio-recorded, transcribed, translated into English, and analysed thematically using the six WHO (World Health Organization) health system building blocks as a theoretical framework. Participants noted both opportunities and challenges around each building block. Identified opportunities were: (a) tailored local health policies and plans, (b) improved health governance at the municipality level, (c) improved health infrastructure and service capacity, (d) improved outreach services, (e) increased resources (health budgets, staffing, and supplies), and (f) improved real-time data reporting from health facilities. At the same time, several challenges were identified including: (a) poor coordination between the tiers of government, (b) delayed release of funds, (c) maldistribution of staff, (d) problems over procurement, and (e) limited monitoring and supervision of the quality of service delivery and data reporting. Our findings suggest that since federalisation, Nepal's health system performance is improving, although much remains to be accomplished. For Nepal to succeed in its federalisation process, understanding the challenges and opportunities is vital to improving each level of the health system in terms of (a) leadership and governance, (b) service delivery, (c) health financing, (d) health workforce, (e) access to essential medicines and technologies and (f) health information system. [Abstract copyright: © 2023. Crown.

Intensive Physiotherapy Interventions in Speedy Recovery of Sub-acute Stroke: A Case Series

Introduction: Intensive physiotherapy interventions have shown good recovery in stroke if applied to stable patients who can tolerate it. Influence of enriched environment on intensive physiotherapy interventions after acute care has not been studied in low-resource contexts, and therefore, we reported outcome of the interventions in multiple cases with stroke in Nepalese context and cultural background. Case reports: Three patients in sub-acute stage of stroke were admitted in intensive physiotherapy treatment unit where the environment was therapeutically enriched. The therapist-administered interventions were intensive for each domain of impairment and activity limitations, every day for six days a week. Patients were trained to carry out caregiver-assisted practice or self-practice in enriched environment. Training demonstrated visible and measurable outcome in all cases. Conclusion: Intensive physiotherapy interventions in an enriched environment promoted good recovery in short period in stroke. The interventions applied, and the principles adopted were based on the established evidence, and therefore findings of this study may support for its feasibility and applicability