1,487 research outputs found
Calculation of the effect of random superfluid density on the temperature dependence of the penetration depth
Microscopic variations in composition or structure can lead to nanoscale
inhomogeneity in superconducting properties such as the magnetic penetration
depth, but measurements of these properties are usually made on longer length
scales. We solve a generalized London equation with a non-uniform penetration
depth, lambda(r), obtaining an approximate solution for the disorder-averaged
Meissner effect. We find that the effective penetration depth is different from
the average penetration depth and is sensitive to the details of the disorder.
These results indicate the need for caution when interpreting measurements of
the penetration depth and its temperature dependence in systems which may be
inhomogeneous
Construction of Non-Perturbative, Unitary Particle-Antiparticle Amplitudes for Finite Particle Number Scattering Formalisms
Starting from a unitary, Lorentz invariant two-particle scattering amplitude
, we show how to use an identification and replacement process to construct a
unique, unitary particle-antiparticle amplitude. This process differs from
conventional on-shell Mandelstam s,t,u crossing in that the input and
constructed amplitudes can be off-diagonal and off-energy shell. Further,
amplitudes are constructed using the invariant parameters which are appropriate
to use as driving terms in the multi-particle, multichannel non-perturbative,
cluster decomposable, relativistic scattering equations of the Faddeev-type
integral equations recently presented by Alfred, Kwizera, Lindesay and Noyes.
It is therefore anticipated that when so employed, the resulting multi-channel
solutions will also be unitary. The process preserves the usual
particle-antiparticle symmetries. To illustrate this process, we construct a
J=0 scattering length model chosen for simplicity. We also exhibit a class of
physical models which contain a finite quantum mass parameter and are Lorentz
invariant. These are constructed to reduce in the appropriate limits, and with
the proper choice of value and sign of the interaction parameter, to the
asymptotic solution of the non-relativistic Coulomb problem, including the
forward scattering singularity, the essential singularity in the phase, and the
Bohr bound-state spectrum
Anti-tubulin drugs conjugated to anti-ErbB antibodies selectively radiosensitize.
Tumour resistance to radiotherapy remains a barrier to improving cancer patient outcomes. To overcome radioresistance, certain drugs have been found to sensitize cells to ionizing radiation (IR). In theory, more potent radiosensitizing drugs should increase tumour kill and improve patient outcomes. In practice, clinical utility of potent radiosensitizing drugs is curtailed by off-target side effects. Here we report potent anti-tubulin drugs conjugated to anti-ErbB antibodies selectively radiosensitize to tumours based on surface receptor expression. While two classes of potent anti-tubulins, auristatins and maytansinoids, indiscriminately radiosensitize tumour cells, conjugating these potent anti-tubulins to anti-ErbB antibodies restrict their radiosensitizing capacity. Of translational significance, we report that a clinically used maytansinoid ADC, ado-trastuzumab emtansine (T-DM1), with IR prolongs tumour control in target expressing HER2+ tumours but not target negative tumours. In contrast to ErbB signal inhibition, our findings establish an alternative therapeutic paradigm for ErbB-based radiosensitization using antibodies to restrict radiosensitizer delivery
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A novel RNA aptamer identifies plasma membrane ATP synthase beta subunit as an early marker and therapeutic target in aggressive cancer
PURPOSE: Primary breast and prostate cancers can be cured, but metastatic disease cannot. Identifying cell factors that predict metastatic potential could guide both prognosis and treatment.
METHODS: We used Cell-SELEX to screen an RNA aptamer library for differential binding to prostate cancer cell lines with high vs. low metastatic potential. Mass spectroscopy, immunoblot, and immunohistochemistry were used to identify and validate aptamer targets. Aptamer properties were tested in vitro, in xenograft models, and in clinical biopsies. Gene expression datasets were queried for target associations in cancer.
RESULTS: We identified a novel aptamer (Apt63) that binds to the beta subunit of F1Fo ATP synthase (ATP5B), present on the plasma membrane of certain normal and cancer cells. Apt63 bound to plasma membranes of multiple aggressive breast and prostate cell lines, but not to normal breast and prostate epithelial cells, and weakly or not at all to non-metastasizing cancer cells; binding led to rapid cell death. A single intravenous injection of Apt63 induced rapid, tumor cell-selective binding and cytotoxicity in MDA-MB-231 xenograft tumors, associated with endonuclease G nuclear translocation and DNA fragmentation. Apt63 was not toxic to non-transformed epithelial cells in vitro or adjacent normal tissue in vivo. In breast cancer tissue arrays, plasma membrane staining with Apt63 correlated with tumor stage (p < 0.0001, n = 416) and was independent of other cancer markers. Across multiple datasets, ATP5B expression was significantly increased relative to normal tissue, and negatively correlated with metastasis-free (p = 0.0063, 0.00039, respectively) and overall (p = 0.050, 0.0198) survival.
CONCLUSION: Ecto-ATP5B binding by Apt63 may disrupt an essential survival mechanism in a subset of tumors with high metastatic potential, and defines a novel category of cancers with potential vulnerability to ATP5B-targeted therapy. Apt63 is a unique tool for elucidating the function of surface ATP synthase, and potentially for predicting and treating metastatic breast and prostate cancer
Compressed Silica Aerogels for the Study of Superfluid 3He
We have performed Small Angle X-ray Scattering (SAXS) on uniaxially strained
aerogels and measured the strain-induced structural anisotropy. We use a model
to connect our SAXS results to anisotropy of the 3He quasiparticle mean free
path in aerogel.Comment: 2 pages, 2 figures, accepted for publication in the proceedings of
the 24th Low Temperature Physics Conferenc
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Liquidity and the drivers of search, due diligence and transaction times for UK commercial real estate investments
Trading commercial real estate involves a process of exchange that is costly and which occurs over an extended and uncertain period of time. This has consequences for the performance and risk of real estate investments. Most research on transaction times has occurred for residential rather than commercial real estate. We study the time taken to transact commercial real estate assets in the UK using a sample of 578 transactions over the period 2004 to 2013. We measure average time to transact from a buyer and seller perspective, distinguishing the search and due diligence phases of the process, and we conduct econometric analysis to explain variation in due diligence times between assets. The median time for purchase of real estate from introduction to completion was 104 days and the median time for sale from marketing to completion was 135 days. There is considerable variation around these times and results suggest that some of this variation is related to market state, type and quality of asset, and type of participants involved in the transaction. Our findings shed light on the drivers of liquidity at an individual asset level and can inform models that quantify the impact of uncertain time on market on real estate investment risk
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