45 research outputs found
Pulsatile tinnitus âa review of 84 patients
Pulsatile tinnitus can be annoying for a patient and can also be the only clue to a potentially devastating and life-threatening disease. In order to understand its clinical spectrum and management better we analysed the files of 84 patients seen at our institution over a 10-year period. Noninvasive techniques (ultrasound, computed tomography, magnetic resonance imaging) and angiography were employed as investigations tailored to the individual patient. A vascular disorder [i.e. arteriovenous fistula, dissection of the internal carotid artery (ICA), fibromuscular dysplasia, aneurysm of the ICA and sinus thrombosis] was found in 36 patients (42%), most commonly a durai arteriovenous fistula or a carotid-cavernous sinus fistula. In 26 patients with a vascular abnormality, pulsatile tinnitus was the presenting symptom. In 12 patients (14%), nonvascular disorders such as glomus tumour or intracranial hypertension with a variety of causes explained the tinnitus. We conclude that patients with pulsatile tinnitus should be investigated with noninvasive techniques. If these are negative or to clarify abnormal findings of noninvasive techniques selective angiography is needed for diagnosis and to guide treatmen
A sulfur-based transport pathway in Cu^+-ATPases
Cells regulate copper levels tightly to balance the biogenesis and integrity of copper centers in vital enzymes against toxic levels of copper. P_(IB)âtype Cu^+âATPases play a central role in copper homeostasis by catalyzing the selective translocation of Cu^+ across cellular membranes. Crystal structures of a copperâfree Cu^+âATPase are available, but the mechanism of Cu^+ recognition, binding, and translocation remains elusive. Through Xâray absorption spectroscopy, ATPase activity assays, and charge transfer measurements on solidâsupported membranes using wildâtype and mutant forms of the Legionella pneumophila Cu^+âATPase (LpCopA), we identify a sulfurâlined metal transport pathway. Structural analysis indicates that Cu^+ is bound at a highâaffinity transmembraneâbinding site in a trigonalâplanar coordination with the Cys residues of the conserved CPC motif of transmembrane segment 4 (C382 and C384) and the conserved Met residue of transmembrane segment 6 (M717 of the MXXXS motif). These residues are also essential for transport. Additionally, the studies indicate essential roles of other conserved intramembranous polar residues in facilitating copper binding to the highâaffinity site and subsequent release through the exit pathway
Quantum Computers and Quantum Coherence
If the states of spins in solids can be created, manipulated, and measured at
the single-quantum level, an entirely new form of information processing,
quantum computing, will be possible. We first give an overview of quantum
information processing, showing that the famous Shor speedup of integer
factoring is just one of a host of important applications for qubits, including
cryptography, counterfeit protection, channel capacity enhancement, distributed
computing, and others. We review our proposed spin-quantum dot architecture for
a quantum computer, and we indicate a variety of first generation materials,
optical, and electrical measurements which should be considered. We analyze the
efficiency of a two-dot device as a transmitter of quantum information via the
ballistic propagation of carriers in a Fermi sea.Comment: 13 pages, latex, one eps figure. Prepared for special issue of J.
Mag. Magn. Matl., "Magnetism beyond 2000". Version 2: small revisions and
correction
Non-maximally entangled states: production, characterization and utilization
Using a spontaneous-downconversion photon source, we produce true
non-maximally entangled states, i.e., without the need for post-selection. The
degree and phase of entanglement are readily tunable, and are characterized
both by a standard analysis using coincidence minima, and by quantum state
tomography of the two-photon state. Using the latter, we experimentally
reconstruct the reduced density matrix for the polarization. Finally, we use
these states to measure the Hardy fraction, obtaining a result that is from any local-realistic result.Comment: 4 pages, 4 figures. To appear in Phys. Rev. Let
Superconductor coupled to two Luttinger liquids as an entangler for electron spins
We consider an s-wave superconductor (SC) which is tunnel-coupled to two
spatially separated Luttinger liquid (LL) leads. We demonstrate that such a
setup acts as an entangler, i.e. it creates spin-singlets of two electrons
which are spatially separated, thereby providing a source of electronic
Einstein-Podolsky-Rosen pairs. We show that in the presence of a bias voltage,
which is smaller than the energy gap in the SC, a stationary current of
spin-entangled electrons can flow from the SC to the LL leads due to Andreev
tunneling events. We discuss two competing transport channels for Cooper pairs
to tunnel from the SC into the LL leads. On the one hand, the coherent
tunneling of two electrons into the same LL lead is shown to be suppressed by
strong LL correlations compared to single-electron tunneling into a LL. On the
other hand, the tunneling of two spin-entangled electrons into different leads
is suppressed by the initial spatial separation of the two electrons coming
from the same Cooper pair. We show that the latter suppression depends
crucially on the effective dimensionality of the SC. We identify a regime of
experimental interest in which the separation of two spin-entangled electrons
is favored. We determine the decay of the singlet state of two electrons
injected into different leads caused by the LL correlations. Although the
electron is not a proper quasiparticle of the LL, the spin information can
still be transported via the spin density fluctuations produced by the injected
spin-entangled electrons.Comment: 15 pages, 2 figure
A high-brightness source of polarization-entangled photons optimized for applications in free space
We present a simple but highly efficient source of polarization-entangled
photons based on spontaneous parametric down-conversion (SPDC) in bulk
periodically poled potassium titanyl phosphate crystals (PPKTP) pumped by a 405
nm laser diode. Utilizing one of the highest available nonlinear coefficients
in a non-degenerate, collinear type-0 phase-matching configuration, we generate
polarization entanglement via the crossed-crystal scheme and detect 0.64
million photon pair events/s/mW, while maintaining an overlap fidelity with the
ideal Bell state of 0.98 at a pump power of 0.025 mW
Decompressive craniectomy plus best medical treatment versus best medical treatment alone for spontaneous severe deep supratentorial intracerebral haemorrhage:a randomised controlled clinical trial
BACKGROUND: It is unknown whether decompressive craniectomy improves clinical outcome for people with spontaneous severe deep intracerebral haemorrhage. The SWITCH trial aimed to assess whether decompressive craniectomy plus best medical treatment in these patients improves outcome at 6 months compared to best medical treatment alone.METHODS: In this multicentre, randomised, open-label, assessor-blinded trial conducted in 42 stroke centres in Austria, Belgium, Finland, France, Germany, the Netherlands, Spain, Sweden, and Switzerland, adults (18-75 years) with a severe intracerebral haemorrhage involving the basal ganglia or thalamus were randomly assigned to receive either decompressive craniectomy plus best medical treatment or best medical treatment alone. The primary outcome was a score of 5-6 on the modified Rankin Scale (mRS) at 180 days, analysed in the intention-to-treat population. This trial is registered with ClincalTrials.gov, NCT02258919, and is completed.FINDINGS: SWITCH had to be stopped early due to lack of funding. Between Oct 6, 2014, and April 4, 2023, 201 individuals were randomly assigned and 197 gave delayed informed consent (96 decompressive craniectomy plus best medical treatment, 101 best medical treatment). 63 (32%) were women and 134 (68%) men, the median age was 61 years (IQR 51-68), and the median haematoma volume 57 mL (IQR 44-74). 42 (44%) of 95 participants assigned to decompressive craniectomy plus best medical treatment and 55 (58%) assigned to best medical treatment alone had an mRS of 5-6 at 180 days (adjusted risk ratio [aRR] 0·77, 95% CI 0·59 to 1·01, adjusted risk difference [aRD] -13%, 95% CI -26 to 0, p=0·057). In the per-protocol analysis, 36 (47%) of 77 participants in the decompressive craniectomy plus best medical treatment group and 44 (60%) of 73 in the best medical treatment alone group had an mRS of 5-6 (aRR 0·76, 95% CI 0·58 to 1·00, aRD -15%, 95% CI -28 to 0). Severe adverse events occurred in 42 (41%) of 103 participants receiving decompressive craniectomy plus best medical treatment and 41 (44%) of 94 receiving best medical treatment.INTERPRETATION: SWITCH provides weak evidence that decompressive craniectomy plus best medical treatment might be superior to best medical treatment alone in people with severe deep intracerebral haemorrhage. The results do not apply to intracerebral haemorrhage in other locations, and survival is associated with severe disability in both groups.FUNDING: Swiss National Science Foundation, Swiss Heart Foundation, Inselspital Stiftung, and Boehringer Ingelheim.</p
Mammalian reproduction overview
The sophisticated control systems that govern reproduction in mammals are usually aimed at ensuring that offspring are born at favourable times of year. Although recent trends in reproductive biology research have tended to become ever more reductionist and focused on cellular and molecular details, we have taken the view in this article that it is equally important to take a step back from this level of detail. We have therefore provided an overview, albeit rather brief, that links reproductive biology with the evolutionary and environmental backgrounds in which this diverse assemblage of species have had to survive and adapt