154 research outputs found
Antiresonance phase shift in strongly coupled cavity QED
We investigate phase shifts in the strong coupling regime of single-atom
cavity quantum electrodynamics (QED). On the light transmitted through the
system, we observe a phase shift associated with an antiresonance and show that
both its frequency and width depend solely on the atom, despite the strong
coupling to the cavity. This shift is optically controllable and reaches 140
degrees - the largest ever reported for a single emitter. Our result offers a
new technique for the characterization of complex integrated quantum circuits.Comment: 5 pages, 5 figure
Continuous parametric feedback cooling of a single atom in an optical cavity
We demonstrate a new feedback algorithm to cool a single neutral atom trapped
inside a standing-wave optical cavity. The algorithm is based on parametric
modulation of the confining potential at twice the natural oscillation
frequency of the atom, in combination with fast and repetitive atomic position
measurements. The latter serve to continuously adjust the modulation phase to a
value for which parametric excitation of the atomic motion is avoided. Cooling
is limited by the measurement back action which decoheres the atomic motion
after only a few oscillations. Nonetheless, applying this feedback scheme to a
~ 5 kHz oscillation mode increases the average storage time of a single atom in
the cavity by a factor of 60 to more than 2 seconds. In contrast to previous
feedback schemes, our algorithm is also capable of cooling a much faster ~ 500
kHz oscillation mode within just microseconds. This demonstrates that
parametric cooling is a powerful technique that can be applied in all
experiments where optical access is limited.Comment: 7 pages, 5 figure
7‑hydroxymitragynine is an active metabolite of mitragynine and a key mediator of its analgesic effects
Mitragynina speciosa, more commonly known as kratom, is a
plant native to Southeast Asia, the leaves of which have been used
traditionally as a stimulant, analgesic, and treatment for opioid addiction. Recently,
growing use of the plant in the United States and concerns that kratom
represents an uncontrolled drug with potential abuse liability, have
highlighted the need for more careful study of its pharmacological activity. The
major active alkaloid found in kratom, mitragynine, has been reported to have
opioid agonist and analgesic activity in vitro
and in animal models, consistent with the purported effects of kratom leaf in
humans. However, preliminary research has provided some evidence that
mitragynine and related compounds may act as atypical opioid agonists, inducing
therapeutic effects such as analgesia, while limiting the negative side effects
typical of classical opioids. Here we report evidence that an active metabolite
plays an important role in mediating the analgesic effects of mitragynine. We
find that mitragynine is converted in
vitro in both mouse and human liver preparations to the much more potent
mu-opioid receptor agonist 7-hydroxymitragynine, and that this conversion is
mediated by cytochrome P450 3A isoforms. Further, we show that 7-hydroxymitragynine
is formed from mitragynine in mice and that brain concentrations of this
metabolite are sufficient to explain most or all of the opioid-receptor-mediated
analgesic activity of mitragynine. At the same time, mitragynine is found in the
brains of mice at very high concentrations relative to its opioid receptor
binding affinity, suggesting that it does not directly activate opioid
receptors. The results presented here provide a metabolism-dependent mechanism
for the analgesic effects of mitragynine and clarify the importance of route of
administration for determining the activity of this compound. Further, they
raise important questions about the interpretation of existing data on
mitragynine and highlight critical areas for further research in animals and
humans.</p
Observation of squeezed light from one atom excited with two photons
Single quantum emitters like atoms are well-known as non-classical light
sources which can produce photons one by one at given times, with reduced
intensity noise. However, the light field emitted by a single atom can exhibit
much richer dynamics. A prominent example is the predicted ability for a single
atom to produce quadrature-squeezed light, with sub-shot-noise amplitude or
phase fluctuations. It has long been foreseen, though, that such squeezing
would be "at least an order of magnitude more difficult" to observe than the
emission of single photons. Squeezed beams have been generated using
macroscopic and mesoscopic media down to a few tens of atoms, but despite
experimental efforts, single-atom squeezing has so far escaped observation.
Here we generate squeezed light with a single atom in a high-finesse optical
resonator. The strong coupling of the atom to the cavity field induces a
genuine quantum mechanical nonlinearity, several orders of magnitude larger
than for usual macroscopic media. This produces observable quadrature squeezing
with an excitation beam containing on average only two photons per system
lifetime. In sharp contrast to the emission of single photons, the squeezed
light stems from the quantum coherence of photon pairs emitted from the system.
The ability of a single atom to induce strong coherent interactions between
propagating photons opens up new perspectives for photonic quantum logic with
single emittersComment: Main paper (4 pages, 3 figures) + Supplementary information (5 pages,
2 figures). Revised versio
Вибір та обґрунтування параметрів технології підтримки стінок стовбура свердловини в осадових породах
Практичне значення роботи полягає в досліджені широкого кола властивостей різних хімічних сполук, покликаних збільшити ступінь стійкості осадових порід в стінках стовбура свердловини; застосування досліджених речовин приведе до істотного підвищення продуктивності бурових робіт, скорочення часу на роботи, пов’язані із ліквідацією ускладнень і аварій в свердловині, або повного виключення останніх, загального зростання ефективності і економічності процесу спорудження свердловин.Мета дипломної роботи: встановлення закономірностей фізико-хімічних процесів, що протікають в стовбурі свердловини, споруджуваної в товщі осадових гірських порід, при циркуляції промивальних рідин і формулюванні на їх основі адекватних технологічних заходів гідравлічної програми промивання свердловини, реалізація якої дозволить надати процесу спорудження свердловин достатньо високу міру продуктивності і економічності
Photon-Atom Coupling with Parabolic Mirrors
Efficient coupling of light to single atomic systems has gained considerable
attention over the past decades. This development is driven by the continuous
growth of quantum technologies. The efficient coupling of light and matter is
an enabling technology for quantum information processing and quantum
communication. And indeed, in recent years much progress has been made in this
direction. But applications aside, the interaction of photons and atoms is a
fundamental physics problem. There are various possibilities for making this
interaction more efficient, among them the apparently 'natural' attempt of
mode-matching the light field to the free-space emission pattern of the atomic
system of interest. Here we will describe the necessary steps of implementing
this mode-matching with the ultimate aim of reaching unit coupling efficiency.
We describe the use of deep parabolic mirrors as the central optical element of
a free-space coupling scheme, covering the preparation of suitable modes of the
field incident onto these mirrors as well as the location of an atom at the
mirror's focus. Furthermore, we establish a robust method for determining the
efficiency of the photon-atom coupling.Comment: Book chapter in compilation "Engineering the Atom-Photon Interaction"
published by Springer in 2015, edited by A. Predojevic and M. W. Mitchell,
ISBN 9783319192307, http://www.springer.com/gp/book/9783319192307. Only
change to version1: now with hyperlinks to arXiv eprints of other book
chapters mentioned in this on
Distribution of Culex coronator in the USA
In 1920, Culex coronator was reported from San Benito, Texas, and later in Arizona, New Mexico, and Oklahoma. In 2005, this species was reported to be spreading across the southeastern USA. Now reported in 14 states, it has been found as far north as northern Oklahoma; Memphis, TN; and Suffolk, VA. The public health significance of Cx. coronator is not firmly established, even though it has been implicated as a potential vector of several arboviral diseases. This study aims to document additional Cx. coronator county-level records, to provide information about its continued expansion across the southern USA, and to provide a short research update into its vector potential. Data acquired through multistate collaborations and author collections resulted in 146 new county records from Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, and Texas. No new county records were presented for Arizona, New Mexico, Tennessee, or Virginia, which had previously reported this species. With these new data, this species has been documented in 386 counties in 14 states of the continental USA.Peer reviewedEntomology and Plant Patholog
Focus on the management of thunderclap headache: from nosography to treatment
Thunderclap headache (TCH) is an excruciating headache characterized by a very sudden onset. Recognition and accurate diagnosis of TCH are important in order to rule out the various, serious underlying brain disorders that, in a high percentage of cases, are the real cause of the headache. Primary TCH, which may recur intermittently and generally has a spontaneous, benign evolution, can thus be diagnosed only when all other potential underlying causes have been excluded through accurate diagnostic work up. In this review, we focus on the management of TCH, paying particular attention to the diagnostic work up and treatment of the condition
Rheumatoid arthritis: pathological mechanisms and modern pharmacologic therapies.
Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease that primarily affects the lining of the synovial joints and is associated with progressive disability, premature death, and socioeconomic burdens. A better understanding of how the pathological mechanisms drive the deterioration of RA progress in individuals is urgently required in order to develop therapies that will effectively treat patients at each stage of the disease progress. Here we dissect the etiology and pathology at specific stages: (i) triggering, (ii) maturation, (iii) targeting, and (iv) fulminant stage, concomitant with hyperplastic synovium, cartilage damage, bone erosion, and systemic consequences. Modern pharmacologic therapies (including conventional, biological, and novel potential small molecule disease-modifying anti-rheumatic drugs) remain the mainstay of RA treatment and there has been significant progress toward achieving disease remission without joint deformity. Despite this, a significant proportion of RA patients do not effectively respond to the current therapies and thus new drugs are urgently required. This review discusses recent advances of our understanding of RA pathogenesis, disease modifying drugs, and provides perspectives on next generation therapeutics for RA
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