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Measurement of process-induced strains in composite materials using embedded fiber optic sensors
This paper presents the results of experiments to measure the internal strains and temperatures that are generated in graphite/epoxy composite specimens during processing using embedded fiber optic strain sensors and thermocouples. Measurements of strain and temperature, combined with a computational model, offer the potential for non-destructive, real-time determination of residual stress in composites, and may be useful for process monitoring and control. Extrinsic Fabry-Perot interferometer, Bragg grating strain sensors, and thermocouples were embedded in graphite/epoxy composite laminates prior to cure. The specimens were cured in a press, and the internal strains and temperatures developed during processing were monitored and recorded. The results are compared with expected values, and limitations of the experimental technique are discussed
Mucociliary clearance as an outcome measure for cystic fibrosis clinical research
Current concepts of cystic fibrosis (CF) pathophysiology link ion transport abnormalities to reduced airway surface liquid (ASL) hydration and impaired mucus clearance. It is likely that correction of the defects that cause ASL dehydration will prevent degradation of mucus clearance, thereby preventing the initiation and/or progression of CF lung disease. A number of novel therapeutic agents aimed at the earliest steps in disease pathogenesis are now under development for the treatment of CF lung disease. Consequently, there is a tremendous need to develop methods that directly assess the effects of these agents on the underlying pathophysiologic process in the target organ. The measurement of mucociliary clearance (MCC) is a highly biologically relevant outcome, but one that is in need of further development. Here, we describe important methodologic aspects of MCC measurement and issues that have limited its use as an outcome measure in the past. Furthermore, we outline the steps that are being carried out now, and will be carried out in the future, to improve the performance of these studies in clinical trials. A systematic approach to optimizing and standardizing the measurement of MCC should greatly advance our ability to assess novel therapies at a relatively early stage of drug development. The resulting data may then be used to select those candidates that should be rapidly advanced into larger clinical trials
First-order interference of nonclassical light emitted spontaneously at different times
We study first-order interference in spontaneous parametric down-conversion
generated by two pump pulses that do not overlap in time. The observed
modulation in the angular distribution of the signal detector counting rate can
only be explained in terms of a quantum mechanical description based on
biphoton states. The condition for observing interference in the signal channel
is shown to depend on the parameters of the idler radiation.Comment: 5 pages, two-column, submitted to PR
Causality - Complexity - Consistency: Can Space-Time Be Based on Logic and Computation?
The difficulty of explaining non-local correlations in a fixed causal
structure sheds new light on the old debate on whether space and time are to be
seen as fundamental. Refraining from assuming space-time as given a priori has
a number of consequences. First, the usual definitions of randomness depend on
a causal structure and turn meaningless. So motivated, we propose an intrinsic,
physically motivated measure for the randomness of a string of bits: its length
minus its normalized work value, a quantity we closely relate to its Kolmogorov
complexity (the length of the shortest program making a universal Turing
machine output this string). We test this alternative concept of randomness for
the example of non-local correlations, and we end up with a reasoning that
leads to similar conclusions as in, but is conceptually more direct than, the
probabilistic view since only the outcomes of measurements that can actually
all be carried out together are put into relation to each other. In the same
context-free spirit, we connect the logical reversibility of an evolution to
the second law of thermodynamics and the arrow of time. Refining this, we end
up with a speculation on the emergence of a space-time structure on bit strings
in terms of data-compressibility relations. Finally, we show that logical
consistency, by which we replace the abandoned causality, it strictly weaker a
constraint than the latter in the multi-party case.Comment: 17 pages, 16 figures, small correction
Entanglement Dynamics in Two-Qubit Open System Interacting with a Squeezed Thermal Bath via Quantum Nondemolition interaction
We analyze the dynamics of entanglement in a two-qubit system interacting
with an initially squeezed thermal environment via a quantum nondemolition
system-reservoir interaction, with the system and reservoir assumed to be
initially separable. We compare and contrast the decoherence of the two-qubit
system in the case where the qubits are mutually close-by (`collective regime')
or distant (`localized regime') with respect to the spatial variation of the
environment. Sudden death of entanglement (as quantified by concurrence) is
shown to occur in the localized case rather than in the collective case, where
entanglement tends to `ring down'. A consequence of the QND character of the
interaction is that the time-evolved fidelity of a Bell state never falls below
, a fact that is useful for quantum communication applications like
a quantum repeater. Using a novel quantification of mixed state entanglement,
we show that there are noise regimes where even though entanglement vanishes,
the state is still available for applications like NMR quantum computation,
because of the presence of a pseudo-pure component.Comment: 17 pages, 9 figures, REVTeX
One-Way Entangled-Photon Autocompensating Quantum Cryptography
A new quantum cryptography implementation is presented that combines one-way
operation with an autocompensating feature that has hitherto only been
available in implementations that require the signal to make a round trip
between the users. Using the concept of advanced waves, it is shown that this
new implementation is related to the round-trip implementations in the same way
that Ekert's two-particle scheme is related to the original one-particle scheme
of Bennett and Brassard. The practical advantages and disadvantages of the
proposed implementation are discussed in the context of existing schemes.Comment: 5 pages, 1 figure; Minor edits--conclusions unchanged; accepted for
publication in Physical Review
Condensation in nongeneric trees
We study nongeneric planar trees and prove the existence of a Gibbs measure
on infinite trees obtained as a weak limit of the finite volume measures. It is
shown that in the infinite volume limit there arises exactly one vertex of
infinite degree and the rest of the tree is distributed like a subcritical
Galton-Watson tree with mean offspring probability . We calculate the rate
of divergence of the degree of the highest order vertex of finite trees in the
thermodynamic limit and show it goes like where is the size of the
tree. These trees have infinite spectral dimension with probability one but the
spectral dimension calculated from the ensemble average of the generating
function for return probabilities is given by if the weight
of a vertex of degree is asymptotic to .Comment: 57 pages, 14 figures. Minor change
The choline transporter Slc44a2 controls platelet activation and thrombosis by regulating mitochondrial function
Genetic factors contribute to the risk of thrombotic diseases. Recent genome wide association studies have identified genetic loci including SLC44A2 which may regulate thrombosis. Here we show that Slc44a2 controls platelet activation and thrombosis by regulating mitochondrial energetics. We find that Slc44a2 null mice (Slc44a2(KO)) have increased bleeding times and delayed thrombosis compared to wild-type (Slc44a2(WT)) controls. Platelets from Slc44a2(KO) mice have impaired activation in response to thrombin. We discover that Slc44a2 mediates choline transport into mitochondria, where choline metabolism leads to an increase in mitochondrial oxygen consumption and ATP production. Platelets lacking Slc44a2 contain less ATP at rest, release less ATP when activated, and have an activation defect that can be rescued by exogenous ADP. Taken together, our data suggest that mitochondria require choline for maximum function, demonstrate the importance of mitochondrial metabolism to platelet activation, and reveal a mechanism by which Slc44a2 influences thrombosis
Interferometric Bell-state preparation using femtosecond-pulse-pumped Spontaneous Parametric Down-Conversion
We present theoretical and experimental study of preparing maximally
entangled two-photon polarization states, or Bell states, using femtosecond
pulse pumped spontaneous parametric down-conversion (SPDC). First, we show how
the inherent distinguishability in femtosecond pulse pumped type-II SPDC can be
removed by using an interferometric technique without spectral and amplitude
post-selection. We then analyze the recently introduced Bell state preparation
scheme using type-I SPDC. Theoretically, both methods offer the same results,
however, type-I SPDC provides experimentally superior methods of preparing Bell
states in femtosecond pulse pumped SPDC. Such a pulsed source of highly
entangled photon pairs is useful in quantum communications, quantum
cryptography, quantum teleportation, etc.Comment: 11 pages, two-column format, to appear in PR
Radioimmunotherapy of B-cell lymphoma with radiolabelled anti-CD20 monoclonal antibodies
CD20 has proven to be an excellent target for the treatment of B-cell lymphoma, first for the chimeric monoclonal antibody rituximab (Rituxan™), and more recently for the radiolabelled antibodies Y-90 ibritumomab tiuxetan (Zevalin™) and I-131 tositumomab (Bexxar™). Radiation therapy effects are due to beta emissions with path lengths of 1–5 mm; gamma radiation emitted by I-131 is the only radiation safety issue for either product. Dose-limiting toxicity for both radiolabelled antibodies is reversible bone marrow suppression. They produce response rates of 70%–90% in low-grade and follicular lymphoma and 40%–50% in transformed low-grade or intermediate-grade lymphomas. Both products produce higher response rates than related unlabelled antibodies, and both are highly active in patients who are relatively resistant to rituximab-based therapy. Median duration of response to a single course of treatment is about 1 year with complete remission rates that last 2 years or longer in about 25% of patients. Clinical trials suggest that anti- CD20 radioimmunotherapy is superior to total body irradiation in patients undergoing stem cell supported therapy for B-cell lymphoma, and that it is a safe and efficacious modality when used as consolidation therapy following chemotherapy. Among cytotoxic treatment options, current evidence suggests that one course of anti-CD20 radioimmunotherapy is as efficacious as six to eight cycles of combination chemotherapy. A major question that persists is how effective these agents are in the setting of rituximab- refractory lymphoma. These products have been underutilised because of the complexity of treatment coordination and concerns regarding reimbursement
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