Thermoelectric Figure of Merit of Strongly Correlated Superlattice Semiconductors

We solved the Anderson Lattice Hamiltonian to get the energy bands of a strongly correlated semiconductor by using slave boson mean field theory. The transport properties were calculated in the relaxation-time approximation,and the thermoelectric figure of merit was obtained for the strongly correlated semiconductor and its superlattice structures. We found that at room temperature $ZT$ can reach nearly 2 for the quantum wire lattice structure.We believe that it is possible to find high values of thermoelectric figure of merit from strongly correlated semiconductor superlattice systems.Comment: 4 pages, 3 figure

Locally critical quantum phase transitions in strongly correlated metals

When a metal undergoes a continuous quantum phase transition, non-Fermi liquid behaviour arises near the critical point. It is standard to assume that all low-energy degrees of freedom induced by quantum criticality are spatially extended, corresponding to long-wavelength fluctuations of the order parameter. However, this picture has been contradicted by recent experiments on a prototype system: heavy fermion metals at a zero-temperature magnetic transition. In particular, neutron scattering from CeCu$_{6-x}$Au$_x$ has revealed anomalous dynamics at atomic length scales, leading to much debate as to the fate of the local moments in the quantum-critical regime. Here we report our theoretical finding of a locally critical quantum phase transition in a model of heavy fermions. The dynamics at the critical point are in agreement with experiment. We also argue that local criticality is a phenomenon of general relevance to strongly correlated metals, including doped Mott insulators.Comment: 20 pages, 3 figures; extended version, to appear in Natur

Extracorporeal liver assist device to exchange albumin and remove endotoxin in acute liver failure: Results of a pivotal pre-clinical study

Background & AimsIn acute liver failure, severity of liver injury and clinical progression of disease are in part consequent upon activation of the innate immune system. Endotoxaemia contributes to innate immune system activation and the detoxifying function of albumin, critical to recovery from liver injury, is irreversibly destroyed in acute liver failure. University College London-Liver Dialysis Device is a novel artificial extracorporeal liver assist device, which is used with albumin infusion, to achieve removal and replacement of dysfunctional albumin and reduction in endotoxaemia. We aimed to test the effect of this device on survival in a pig model of acetaminophen-induced acute liver failure.MethodsPigs were randomised to three groups: Acetaminophen plus University College London-Liver Dialysis Device (n=9); Acetaminophen plus Control Device (n=7); and Control plus Control Device (n=4). Device treatment was initiated two h after onset of irreversible acute liver failure.ResultsThe Liver Dialysis Device resulted in 67% reduced risk of death in acetaminophen-induced acute liver failure compared to Control Device (hazard ratio=0.33, p=0.0439). This was associated with 27% decrease in circulating irreversibly oxidised human non-mercaptalbumin-2 throughout treatment (p=0.046); 54% reduction in overall severity of endotoxaemia (p=0.024); delay in development of vasoplegia and acute lung injury; and delay in systemic activation of the TLR4 signalling pathway. Liver Dialysis Device-associated adverse clinical effects were not seen.ConclusionsThe survival benefit and lack of adverse effects would support clinical trials of University College London-Liver Dialysis Device in acute liver failure patients

Local fluctuations in quantum critical metals

We show that spatially local, yet low-energy, fluctuations can play an essential role in the physics of strongly correlated electron systems tuned to a quantum critical point. A detailed microscopic analysis of the Kondo lattice model is carried out within an extended dynamical mean-field approach. The correlation functions for the lattice model are calculated through a self-consistent Bose-Fermi Kondo problem, in which a local moment is coupled both to a fermionic bath and to a bosonic bath (a fluctuating magnetic field). A renormalization-group treatment of this impurity problem--perturbative in $\epsilon=1-\gamma$, where $\gamma$ is an exponent characterizing the spectrum of the bosonic bath--shows that competition between the two couplings can drive the local-moment fluctuations critical. As a result, two distinct types of quantum critical point emerge in the Kondo lattice, one being of the usual spin-density-wave type, the other ``locally critical.'' Near the locally critical point, the dynamical spin susceptibility exhibits $\omega/T$ scaling with a fractional exponent. While the spin-density-wave critical point is Gaussian, the locally critical point is an interacting fixed point at which long-wavelength and spatially local critical modes coexist. A Ginzburg-Landau description for the locally critical point is discussed. It is argued that these results are robust, that local criticality provides a natural description of the quantum critical behavior seen in a number of heavy-fermion metals, and that this picture may also be relevant to other strongly correlated metals.Comment: 20 pages, 12 figures; typos in figure 3 and in the main text corrected, version as publishe

Komplementära och alternativa behandlingsmetoder för sport- och sällskapsdjur- en systematisk litteraturöversikt

Komplementär och alternativ veterinärmedicin (KAVM) är ett svårdefinierat område och omfattar en rad sinsemellan olika behandlingsmetoder. KAVM-metoder finns representerade längs en hel ”gråskala”, från de som i vetenskapliga studier uppvisat dokumenterade förklaringsmodeller, till de som visat sig vara verkningslösa. Det är metoder som idag till stor del utförs utanför den konventionella djursjukvården.Syftet med projektet har varit att systematiskt gå igenom den vetenskapliga dokumentationen för ett urval KAVM-metoder vad gäller klinisk effekt på djurslagen häst, hund och katt. Rapporten syftar till att höja kunskapsnivån bland djurhälsopersonal, terapeuter, djurägare, försäkringsbolag och myndigheter.Vi har genomfört systematiska litteraturöversikter av metoder inom grupperna akupunktur, elektroterapi, ljusterapi, mjukdelsbehandling, mobiliserings- och manipulationsmetoder, samt ”övriga terapier”. Detta arbete omfattar således även metoder som ingår i den konventionella humansjukvården, och som i viss mån även används inom djurhälsovård. Litteratursökningar gjordes i databaserna Web of Science Core Collection, CABI och PubMed och inkluderade artiklar publicerade under åren 1980-2020. Totalt 16071 artiklar identifierades och av dessa motsvarade 258 i förväg satta inklusionskriterier.Av de inkluderade metoderna uppvisade majoriteten bristande vetenskaplig dokumentation och var av otillräcklig kvalitet för att kunna dra någon slutsats om metodernas effekt, på en specifik indikation och för djurslagen häst, hund och katt. Våra systematiska översikter indikerar att vissa KVAM-metoder skulle kunna vara värda att utvärderas i högkvalitativa prövningar, t.ex. akupunktur, extrakorporal stötvågsbehandling, terapeutiskt ultraljud, pulserande elektromagnetisk terapi och laserbehandling. Likaså skulle resultat från humanmedicinska studier tillsammans med enstaka gynnsamma resultat från djurstudier kunna motivera fördjupade interventionsstudier. Dit hör t.ex. massage, vissa elektroterapier och high-velocity low-amplitude-behandling. För övriga metoder finns för lite vetenskaplig dokumentation för att kunna säga hur de bör prioriteras för vidare forskning.Den primära begränsningen ligger hos de studier som granskats: bristen på publikationer av god vetenskplig kvalitet och en stor variation i indikationer, tillämpade tekniker, behandlingsprotokoll och resultatvariabler mellan studier. Sammantaget har dessa brister förhindrat en meningsfull tolkning av den totala kliniska effekten av enskilda KVAM-terapier. Rapporten ger en sammanfattning av den vetenskapliga dokumentationen om utvalda KAVM-metoder. Den identifierar dessutom omfattningen av metodernas vetenskapliga underlag och ger utförlig information om kunskapsläget, att användas av djurhälsopersonal, djurägare, försäkringsbolag och myndigheter

Concussion Symptom Inventory: An Empirically Derived Scale for Monitoring Resolution of Symptoms Following Sport-Related Concussion

Self-report post-concussion symptom scales have been a key method for monitoring recovery from sport-related concussion, to assist in medical management, and return-to-play decision-making. To date, however, item selection and scaling metrics for these instruments have been based solely upon clinical judgment, and no one scale has been identified as the “gold standard”. We analyzed a large set of data from existing scales obtained from three separate case–control studies in order to derive a sensitive and efficient scale for this application by eliminating items that were found to be insensitive to concussion. Baseline data from symptom checklists including a total of 27 symptom variables were collected from a total of 16,350 high school and college athletes. Follow-up data were obtained from 641 athletes who subsequently incurred a concussion. Symptom checklists were administered at baseline (preseason), immediately post-concussion, post-game, and at 1, 3, and 5 days post-injury. Effect-size analyses resulted in the retention of only 12 of the 27 variables. Receiver-operating characteristic analyses were used to confirm that the reduction in items did not reduce sensitivity or specificity. The newly derived Concussion Symptom Inventory is presented and recommended as a research and clinical tool for monitoring recovery from sport-related concussion

Photoenhanced metastable c-axis electrodynamics in stripe-ordered cuprate La1.885Ba0.115CuO4.

Quantum materials are amenable to nonequilibrium manipulation with light, enabling modification and control of macroscopic properties. Light-based augmentation of superconductivity is particularly intriguing. Copper-oxide superconductors exhibit complex interplay between spin order, charge order, and superconductivity, offering the prospect of enhanced coherence by altering the balance between competing orders. We utilize terahertz time-domain spectroscopy to monitor the c-axis Josephson plasma resonance (JPR) in La2-xBaxCuO4 (x = 0.115) as a direct probe of superconductivity dynamics following excitation with near-infrared pulses. Starting from the superconducting state, c-axis polarized excitation with a fluence of 100 μJ/cm2 results in an increase of the far-infrared spectral weight by more than an order of magnitude as evidenced by a blueshift of the JPR, interpreted as resulting from nonthermal collapse of the charge order. The photoinduced signal persists well beyond our measurement window of 300 ps and exhibits signatures of spatial inhomogeneity. The electrodynamic response of this metastable state is consistent with enhanced superconducting fluctuations. Our results reveal that La2-xBaxCuO4 is highly sensitive to nonequilibrium excitation over a wide fluence range, providing an unambiguous example of photoinduced modification of order-parameter competition