682 research outputs found
Timber construction and material information exchanges for the design of complex geometrical structures
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2010.Page 77 blank. Cataloged from PDF version of thesis.Includes bibliographical references (p. 74).In a universe made of bits where everything is continuously computing and nature itself is processing information everyday, what is it that our materials compute? Specifically, what are the bits of information registered within timber? More importantly, in this universe made of bits how do we design using this information and how do we imagine new buildings? This thesis explores the use of wood as a natural material in the design and construction of complex geometrical timber structures by capturing the natural curvature found in timber into digital data and building a framework for surface timber mapping as a design method. Key results include a detailed framework for translation, method for timber mapping and a prototype utilizing this method. Future steps include growth of timber structures and the use of living material in combination with typical timber construction methods for the design and construction of future buildings.by German Walter Aparicio Jr.S.M
Neutralino dark matter in mSUGRA/CMSSM with a 125 GeV light Higgs scalar
The minimal supergravity (mSUGRA or CMSSM) model is an oft-used framework for
exhibiting the properties of neutralino (WIMP) cold dark matter (CDM). However,
the recent evidence from Atlas and CMS on a light Higgs scalar with mass
m_h\simeq 125 GeV highly constrains the superparticle mass spectrum, which in
turn constrains the neutralino annihilation mechanisms in the early universe.
We find that stau and stop co-annihilation mechanisms -- already highly
stressed by the latest Atlas/CMS results on SUSY searches -- are nearly
eliminated if indeed the light Higgs scalar has mass m_h\simeq 125 GeV.
Furthermore, neutralino annihilation via the A-resonance is essentially ruled
out in mSUGRA so that it is exceedingly difficult to generate
thermally-produced neutralino-only dark matter at the measured abundance. The
remaining possibility lies in the focus-point region which now moves out to
m_0\sim 10-20 TeV range due to the required large trilinear soft SUSY breaking
term A_0. The remaining HB/FP region is more fine-tuned than before owing to
the typically large top squark masses. We present updated direct and indirect
detection rates for neutralino dark matter, and show that ton scale noble
liquid detectors will either discover mixed higgsino CDM or essentially rule
out thermally-produced neutralino-only CDM in the mSUGRA model.Comment: 17 pages including 9 .eps figure
Life-threatening acute acalculous cholecystitis in a patient with renal cell carcinoma treated by sunitinib: a case report
<p>Abstract</p> <p>Introduction</p> <p>Sunitinib, an oral multitargeted tyrosine kinase inhibitor, is widely used in the treatment of renal cell carcinoma and gastrointestinal stromal tumor and has had a variety of adverse events. However, sunitinib-related acute cholecystitis has been reported in only two patients with gastrointestinal stromal tumor and renal cell carcinoma (clear cell subtype).</p> <p>Case presentation</p> <p>A 75-year-old Japanese woman with a right sided abdominal swelling was referred to our hospital. Computed tomography (CT) showed a hypervascular bulky tumor in her right kidney, suggesting right renal cell carcinoma in clinical T4N0M0. Although sunitinib therapy was started as neoadjuvant chemotherapy, during the fourth week of the first cycle, she developed acute acalculous cholecystitis and disseminated intravascular coagulation associated with sunitinib. Sunitinib therapy was discontinued immediately and she recovered after subsequent treatment with antibiotics and gabexate mesilate followed by percutaneous cholecystostomy. Cholecystectomy and right radical nephrectomy were performed and pathological examination showed that her renal tumor was a chromophobe renal cell carcinoma (pT2) with necrosis. Inflammation and ischemia were observed in the gallbladder wall, which was compatible with acute acalculous cholecystitis. There has been no evidence of disease recurrence for more than six months.</p> <p>Conclusion</p> <p>We described the third case of sunitinib-related acute cholecystitis in a patient with chromophobe renal cell carcinoma. Attention is required to sunitinib-related acute cholecystitis which, while uncommon, could be life-threatening.</p
Flux and Instanton Effects in Local F-theory Models and Hierarchical Fermion Masses
We study the deformation induced by fluxes and instanton effects on Yukawa
couplings involving 7-brane intersections in local F-theory constructions. In
the absence of non-perturbative effects, holomorphic Yukawa couplings do not
depend on open string fluxes. On the other hand instanton effects (or gaugino
condensation on distant 7-branes) do induce corrections to the Yukawas. The
leading order effect may also be captured by the presence of closed string
(1,2) IASD fluxes, which give rise to a non-commutative structure. We check
that even in the presence of these non-perturbative effects the holomorphic
Yukawas remain independent of magnetic fluxes. Although fermion mass
hierarchies may be obtained from these non-perturbative effects, they would
give identical Yukawa couplings for D-quark and Lepton masses in SU(5) F-theory
GUT's, in contradiction with experiment. We point out that this problem may be
solved by appropriately normalizing the wavefunctions. We show in a simple toy
model how the presence of hypercharge flux may then be responsible for the
difference between D-quarks and Lepton masses in local SU(5) GUT's.Comment: 84 pages, 1 figure. v2: minor corrections and references adde
Quasi-coherent fluctuations limiting the pedestal growth on Alcator C-Mod: experiment and modelling
Performance predictions for future fusion devices rely on an accurate model of the pedestal structure. The candidate for predictive pedestal structure is EPED, and it is imperative to test the underlying hypotheses to further gain confidence for ITER projections. Here, we present experimental work testing one of the EPED hypotheses, namely the existence of a soft limit set by microinstabilities such as the kinetic ballooning mode. This work extends recent work on Alactor C-Mod (Diallo et al 2014 Phys. Rev. Lett. 112 115001), to include detailed measurements of the edge fluctuations and comparisons of edge simulation codes and experimental observations
Non-local heat transport in Alcator C-Mod ohmic L-mode plasmas
Non-local heat transport experiments were performed in Alcator C-Mod ohmic L-mode plasmas by inducing edge cooling with laser blow-off impurity (CaF2) injection. The non-local effect, a cooling of the edge electron temperature with a rapid rise of the central electron temperature, which contradicts the assumption of 'local' transport, was observed in low collisionality linear ohmic confinement (LOC) regime plasmas. Transport analysis shows this phenomenon can be explained either by a fast drop of the core diffusivity, or the sudden appearance of a heat pinch. In high collisionality saturated ohmic confinement (SOC) regime plasmas, the thermal transport becomes 'local': the central electron temperature drops on the energy confinement time scale in response to the edge cooling. Measurements from a high resolution imaging x-ray spectrometer show that the ion temperature has a similar behaviour as the electron temperature in response to edge cooling, and that the transition density of non-locality correlates with the rotation reversal critical density. This connection may indicate the possible connection between thermal and momentum transport, which is also linked to a transition in turbulence dominance between trapped electron modes (TEMs) and ion temperature gradient (ITG) modes. Experiments with repetitive cold pulses in one discharge were also performed to allow Fourier analysis and to provide details of cold front propagation. These modulation experiments showed in LOC plasmas that the electron thermal transport is not purely diffusive, while in SOC the electron thermal transport is more diffusive like. Linear gyrokinetic simulations suggest the turbulence outside r/a = 0.75 changes from TEM dominance in LOC plasmas to ITG mode dominance in SOC plasmas.United States. Dept. of Energy (DoE Contract No DE-FC02-99ER54512)Oak Ridge Institute for Science and Education (DOE Fusion Energy Postdoctoral Research Program
Higgs decay to dark matter in low energy SUSY: is it detectable at the LHC ?
Due to the limited statistics so far accumulated in the Higgs boson search at
the LHC, the Higgs boson property has not yet been tightly constrained and it
is still allowed for the Higgs boson to decay invisibly to dark matter with a
sizable branching ratio. In this work, we examine the Higgs decay to neutralino
dark matter in low energy SUSY by considering three different models: the
minimal supersymmetric standard model (MSSM), the next-to-minimal
supersymmetric standard models (NMSSM) and the nearly minimal supersymmetric
standard model (nMSSM). Under current experimental constraints at 2-sigma level
(including the muon g-2 and the dark matter relic density), we scan over the
parameter space of each model. Then in the allowed parameter space we calculate
the branching ratio of the SM-like Higgs decay to neutralino dark matter and
examine its observability at the LHC by considering three production channels:
the weak boson fusion VV->h, the associated production with a Z-boson pp->hZ+X
or a pair of top quarks pp->htt_bar+X. We find that in the MSSM such a decay is
far below the detectable level; while in both the NMSSM and nMSSM the decay
branching ratio can be large enough to be observable at the LHC.Comment: Version in JHE
J-PAS: Forecasts for dark matter - dark energy elastic couplings
We consider a cosmological model where dark matter and dark energy feature a
coupling that only affects their momentum transfer in the corresponding Euler
equations. We perform a fit to cosmological observables and confirm previous
findings within these scenarios that favour the presence of a coupling at more
than . This improvement is driven by the Sunyaev-Zeldovich data. We
subsequently perform a forecast for future J-PAS data and find that clustering
measurements will permit to clearly discern the presence of an interaction
within a few percent level with the uncoupled case at more than when
the complete survey, covering sq. deg., is considered. We found that the
inclusion of weak lensing measurements will not help to further constrain the
coupling parameter. For completeness, we compare to forecasts for DESI and
Euclid, which provide similar discriminating power.Comment: 34 pages, 17 figures, added some clarifications and discussions,
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