265 research outputs found
Electrical Manipulation of Telecom Color Centers in Silicon
Silicon color centers have recently emerged as promising candidates for
commercial quantum technology, yet their interaction with electric fields has
yet to be investigated. In this paper, we demonstrate electrical manipulation
of telecom silicon color centers by fabricating lateral electrical diodes with
an integrated G center ensemble in a commercial silicon on insulator wafer. The
ensemble optical response is characterized under application of a
reverse-biased DC electric field, observing both 100% modulation of
fluorescence signal, and wavelength redshift of approximately 1.4 GHz/V above a
threshold voltage. Finally, we use G center fluorescence to directly image the
electric field distribution within the devices, obtaining insight into the
spatial and voltage-dependent variation of the junction depletion region and
the associated mediating effects on the ensemble. Strong correlation between
emitter-field coupling and generated photocurrent is observed. Our
demonstration enables electrical control and stabilization of semiconductor
quantum emitters
Microcystin Prevalence throughout Lentic Waterbodies in Coastal Southern California.
Toxin producing cyanobacterial blooms have increased globally in recent decades in both frequency and intensity. Despite the recognition of this growing risk, the extent and magnitude of cyanobacterial blooms and cyanotoxin prevalence is poorly characterized in the heavily populated region of southern California. Recent assessments of lentic waterbodies (depressional wetlands, lakes, reservoirs and coastal lagoons) determined the prevalence of microcystins and, in some cases, additional cyanotoxins. Microcystins were present in all waterbody types surveyed although toxin concentrations were generally low across most habitats, as only a small number of sites exceeded California's recreational health thresholds for acute toxicity. Results from passive samplers (Solid Phase Adsorption Toxin Tracking (SPATT)) indicated microcystins were prevalent throughout lentic waterbodies and that traditional discrete samples underestimated the presence of microcystins. Multiple cyanotoxins were detected simultaneously in some systems, indicating multiple stressors, the risk of which is uncertain since health thresholds are based on exposures to single toxins. Anatoxin-a was detected for the first time from lakes in southern California. The persistence of detectable microcystins across years and seasons indicates a low-level, chronic risk through both direct and indirect exposure. The influence of toxic cyanobacterial blooms is a more complex stressor than presently recognized and should be included in water quality monitoring programs
Microcystin Prevalence throughout Lentic Waterbodies in Coastal Southern California.
Toxin producing cyanobacterial blooms have increased globally in recent decades in both frequency and intensity. Despite the recognition of this growing risk, the extent and magnitude of cyanobacterial blooms and cyanotoxin prevalence is poorly characterized in the heavily populated region of southern California. Recent assessments of lentic waterbodies (depressional wetlands, lakes, reservoirs and coastal lagoons) determined the prevalence of microcystins and, in some cases, additional cyanotoxins. Microcystins were present in all waterbody types surveyed although toxin concentrations were generally low across most habitats, as only a small number of sites exceeded California's recreational health thresholds for acute toxicity. Results from passive samplers (Solid Phase Adsorption Toxin Tracking (SPATT)) indicated microcystins were prevalent throughout lentic waterbodies and that traditional discrete samples underestimated the presence of microcystins. Multiple cyanotoxins were detected simultaneously in some systems, indicating multiple stressors, the risk of which is uncertain since health thresholds are based on exposures to single toxins. Anatoxin-a was detected for the first time from lakes in southern California. The persistence of detectable microcystins across years and seasons indicates a low-level, chronic risk through both direct and indirect exposure. The influence of toxic cyanobacterial blooms is a more complex stressor than presently recognized and should be included in water quality monitoring programs
A new clinico-pathological classification system for mesial temporal sclerosis
We propose a histopathological classification system for hippocampal cell loss in patients suffering from mesial temporal lobe epilepsies (MTLE). One hundred and seventy-eight surgically resected specimens were microscopically examined with respect to neuronal cell loss in hippocampal subfields CA1–CA4 and dentate gyrus. Five distinct patterns were recognized within a consecutive cohort of anatomically well-preserved surgical specimens. The first group comprised hippocampi with neuronal cell densities not significantly different from age matched autopsy controls [no mesial temporal sclerosis (no MTS); n = 34, 19%]. A classical pattern with severe cell loss in CA1 and moderate neuronal loss in all other subfields excluding CA2 was observed in 33 cases (19%), whereas the vast majority of cases showed extensive neuronal cell loss in all hippocampal subfields (n = 94, 53%). Due to considerable similarities of neuronal cell loss patterns and clinical histories, we designated these two groups as MTS type 1a and 1b, respectively. We further distinguished two atypical variants characterized either by severe neuronal loss restricted to sector CA1 (MTS type 2; n = 10, 6%) or to the hilar region (MTS type 3, n = 7, 4%). Correlation with clinical data pointed to an early age of initial precipitating injury (IPI < 3 years) as important predictor of hippocampal pathology, i.e. MTS type 1a and 1b. In MTS type 2, IPIs were documented at a later age (mean 6 years), whereas in MTS type 3 and normal appearing hippocampus (no MTS) the first event appeared beyond the age of 13 and 16 years, respectively. In addition, postsurgical outcome was significantly worse in atypical MTS, especially MTS type 3 with only 28% of patients having seizure relief after 1-year follow-up period, compared to successful seizure control in MTS types 1a and 1b (72 and 73%). Our classification system appears suitable for stratifying the clinically heterogeneous group of MTLE patients also with respect to postsurgical outcome studies
International Veterinary Epilepsy Task Force consensus proposal: Medical treatment of canine epilepsy in Europe
In Europe, the number of antiepileptic drugs (AEDs) licensed for dogs has grown considerably over the last years. Nevertheless, the same questions remain, which include, 1) when to start treatment, 2) which drug is best used initially, 3) which adjunctive AED can be advised if treatment with the initial drug is unsatisfactory, and 4) when treatment changes should be considered. In this consensus proposal, an overview is given on the aim of AED treatment, when to start long-term treatment in canine epilepsy and which veterinary AEDs are currently in use for dogs. The consensus proposal for drug treatment protocols, 1) is based on current published evidence-based literature, 2) considers the current legal framework of the cascade regulation for the prescription of veterinary drugs in Europe, and 3) reflects the authors’ experience. With this paper it is aimed to provide a consensus for the management of canine idiopathic epilepsy. Furthermore, for the management of structural epilepsy AEDs are inevitable in addition to treating the underlying cause, if possible
Hyperfine Spectroscopy of Isotopically Engineered Group-IV Color Centers in Diamond
A quantum register coupled to a spin-photon interface is a key component in
quantum communication and information processing. Group-IV color centers in
diamond (SiV, GeV, and SnV) are promising candidates for this application,
comprising an electronic spin with optical transitions coupled to a nuclear
spin as the quantum register. However, the creation of a quantum register for
these color centers with deterministic and strong coupling to the spin-photon
interface remains challenging. Here, we make first-principles predictions of
the hyperfine parameters of the group-IV color centers, which we verify
experimentally with a comprehensive comparison between the spectra of spin
active and spin neutral intrinsic dopant nuclei in single GeV and SnV emitters.
In line with the theoretical predictions, detailed spectroscopy on large sample
sizes reveals that hyperfine coupling causes a splitting of the optical
transition of SnV an order of magnitude larger than the optical linewidth and
provides a magnetic-field insensitive transition. This strong coupling provides
access to a new regime for quantum registers in diamond color centers, opening
avenues for novel spin-photon entanglement and quantum sensing schemes for
these well-studied emitters
Lovastatin Modulates Glycogen Synthase Kinase-3β Pathway and Inhibits Mossy Fiber Sprouting after Pilocarpine-Induced Status Epilepticus
This study was undertaken to assay the effect of lovastatin on the glycogen synthase kinase-3 beta (GSK-3β) and collapsin responsive mediator protein-2 (CRMP-2) signaling pathway and mossy fiber sprouting (MFS) in epileptic rats. MFS in the dentate gyrus (DG) is an important feature of temporal lobe epilepsy (TLE) and is highly related to the severity and the frequency of spontaneous recurrent seizures. However, the molecular mechanism of MFS is mostly unknown. GSK-3β and CRMP-2 are the genes responsible for axonal growth and neuronal polarity in the hippocampus, therefore this pathway is a potential target to investigate MFS. Pilocarpine-induced status epilepticus animal model was taken as our researching material. Western blot, histological and electrophysiological techniques were used as the studying tools. The results showed that the expression level of GSK-3β and CRMP-2 were elevated after seizure induction, and the administration of lovastatin reversed this effect and significantly reduced the extent of MFS in both DG and CA3 region in the hippocampus. The alteration of expression level of GSK-3β and CRMP-2 after seizure induction proposes that GSK-3β and CRMP-2 are crucial for MFS and epiletogenesis. The fact that lovastatin reversed the expression level of GSK-3β and CRMP-2 indicated that GSK-3β and CRMP-2 are possible to be a novel mechanism of lovatstain to suppress MFS and revealed a new therapeutic target and researching direction for studying the mechanism of MFS and epileptogenesis
Coastal groundwater discharge – an additional source of phosphorus for the oligotrophic wetlands of the Everglades
In this manuscript we define a new term we call coastal groundwater discharge (CGD), which is related to submarine groundwater discharge (SGD), but occurs when seawater intrudes inland to force brackish groundwater to discharge to the coastal wetlands. A hydrologic and geochemical investigation of both the groundwater and surface water in the southern Everglades was conducted to investigate the occurrence of CGD associated with seawater intrusion. During the wet season, the surface water chemistry remained fresh. Enhanced chloride, sodium, and calcium concentrations, indicative of brackish groundwater discharge, were observed in the surface water during the dry season. Brackish groundwaters of the southern Everglades contain 1–2.3μM concentrations of total phosphorus (TP). These concentrations exceed the expected values predicted by conservative mixing of local fresh groundwater and intruding seawater, which both have TPμM. The additional source of TP may be from seawater sediments or from the aquifer matrix as a result of water–rock interactions (such as carbonate mineral dissolution and ion exchange reactions) induced by mixing fresh groundwater with intruding seawater. We hypothesize that CGD maybe an additional source of phosphorus (a limiting nutrient) to the coastal wetlands of the southern Everglades
Telecom networking with a diamond quantum memory
Practical quantum networks require interfacing quantum memories with existing
channels and systems that operate in the telecom band. Here we demonstrate
low-noise, bidirectional quantum frequency conversion that enables a
solid-state quantum memory to directly interface with telecom-band systems. In
particular, we demonstrate conversion of visible-band single photons emitted
from a silicon-vacancy (SiV) center in diamond to the telecom O-band,
maintaining low noise () and high indistinguishability
(). We further demonstrate the utility of this system for quantum
networking by converting telecom-band time-bin pulses, sent across a lossy and
noisy 50 km deployed fiber link, to the visible band and mapping their quantum
states onto a diamond quantum memory with fidelity .
These results demonstrate the viability of SiV quantum memories integrated with
telecom-band systems for scalable quantum networking applications.Comment: 9 pages, 5 figures + Supplemental Material
Development of a Boston-area 50-km fiber quantum network testbed
Distributing quantum information between remote systems will necessitate the
integration of emerging quantum components with existing communication
infrastructure. This requires understanding the channel-induced degradations of
the transmitted quantum signals, beyond the typical characterization methods
for classical communication systems. Here we report on a comprehensive
characterization of a Boston-Area Quantum Network (BARQNET) telecom fiber
testbed, measuring the time-of-flight, polarization, and phase noise imparted
on transmitted signals. We further design and demonstrate a compensation system
that is both resilient to these noise sources and compatible with integration
of emerging quantum memory components on the deployed link. These results have
utility for future work on the BARQNET as well as other quantum network
testbeds in development, enabling near-term quantum networking demonstrations
and informing what areas of technology development will be most impactful in
advancing future system capabilities.Comment: 9 pages, 5 figures + Supplemental Material
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