1,271 research outputs found
Unoriented topological quantum field theory and link homology
We investigate link homology theories for stable equivalence classes of link
diagrams on orientable surfaces. We apply (1+1)-dimensional unoriented
topological quantum field theories to Bar-Natan's geometric formalism to define
new theories for stable equivalence classes.Comment: This is the version published by Algebraic & Geometric Topology on 24
August 200
A spectroscopic search for White Dwarf companions to 101 nearby M dwarfs
Recent studies of the stellar population in the solar neighborhood (<20 pc)
suggest that there are undetected white dwarfs (WDs) in multiple systems with
main sequence companions. Detecting these hidden stars and obtaining a more
complete census of nearby WDs is important for our understanding of binary and
galactic evolution, as well as the study of explosive phenomena. In an attempt
to uncover these hidden WDs, we present intermediate resolution spectroscopy
over the wavelength range 3000-25000 \AA\ of 101 nearby M dwarfs (dMs),
observed with the Very Large Telescope X-Shooter spectrograph. For each star we
search for a hot component superimposed on the dM spectrum. X-Shooter has
excellent blue sensitivity and thus can reveal a faint hot WD despite the
brightness of its red companion. Visual examination shows no clear evidence of
a WD in any of the spectra. We place upper limits on the effective temperatures
of WDs that may still be hiding by fitting dM templates to the spectra, and
modeling WD spectra. On average our survey is sensitive to WDs hotter than
about 5300 K. This suggests that the frequency of WD companions of T<5300 K
with separation of order <50 AU among the local dM population is <3% at the 95%
confidence level. The reduced spectra are made available on via WISeREP
repository.Comment: 41 pages, 105 figures, 2 tables. Submitted to AAS journal
Multifunction automated crawling system
The present invention is an automated crawling robot system including a platform, a first leg assembly, a second leg assembly, first and second rails attached to the platform, and an onboard electronic computer controller. The first leg assembly has an intermittent coupling device and the second leg assembly has an intermittent coupling device for intermittently coupling the respective first and second leg assemblies to a particular object. The first and second leg assemblies are slidably coupled to the rail assembly and are slidably driven by motors to thereby allow linear movement. In addition, the first leg assembly is rotary driven by a rotary motor to thereby provide rotary motion relative to the platform. To effectuate motion, the intermittent coupling devices of the first and second leg assemblies alternately couple the respective first and second leg assemblies to an object. This motion is done while simultaneously moving one of the leg assemblies linearly in the desired direction and preparing the next step. This arrangement allows the crawler of the present invention to traverse an object in a range of motion covering 360 degrees
Tumor bed brachytherapy for locally advanced laryngeal cancer: a feasibility assessment of combination with ferromagnetic hyperthermia
Purpose. To assess the feasibility of adding hyperthermia to an original method of organ-preserving brachytherapy treatment for locally advanced head and neck tumors. Methods and materials. The method involves organ-preserving tumor resection and adjunctive high-dose-rate (HDR) brachytherapy delivered via afterloading catheters. These catheters are embedded in a polymeric implant prepared intraoperatively to fill the resection cavity, allowing precise computer planning of dose distribution in the surrounding at-risk tumor bed tissue. Theoretical and experimental analyzes address the feasibility of heating the tumor bed implant by coupling energy from a 100 kHz magnetic field applied externally into ferromagnetic particles, which are uniformly distributed within the implant. The goal is to combine adjuvant hyperthermia (40 °C–45 °C) to at-risk tissue within 5 mm of the resection cavity for thermal enhancement of radiation and chemotherapy response. Results. A five-year relapse free survival rate of 95.8% was obtained for a select group of 48 male patients with T3N0M0 larynx tumors, when combining organ-preserving surgery with HDR brachytherapy from a tumor bed implant. Anticipating the need for additional treatment in patients with more advanced disease, a theoretical analysis demonstrates the ability to heat at-risk tissue up to 10 mm from the surface of an implant filled with magnetically coupled ferromagnetic balls. Using a laboratory induction heating system, it takes just over 2 min to increase the target tissue temperature by 10 °C using a 19% volume fraction of ferromagnetic spheres in a 2 cm diameter silicone implant. Conclusion. The promising clinical results of a 48 patient pilot study demonstrate the feasibility of a new organ sparing treatment for laryngeal cancer. Anticipating the need for additional therapy, theoretical estimations of potential implant heating are confirmed with laboratory experiments, preparing the way for future implementation of a thermobrachytherapy implant approach for organ-sparing treatment of locally advanced laryngeal cancer
Big flip graphs and their automorphism groups
In this paper, we study the relationship between the mapping class
group of an infinite-type surface and the simultaneous flip graph,
a variant of the flip graph for infinite-type surfaces defined by
Fossas and Parlier [6]. We show that the extended
mapping class group is isomorphic to a proper subgroup of the
automorphism group of the flip graph, unlike in the finite-type
case. This shows that Ivanov\u27s metaconjecture, which states that
any “sufficiently rich" object associated to a finite-type surface
has the extended mapping class group as its automorphism group, does
not extend to simultaneous flip graphs of infinite-type surfaces
Scoring Dawg Core Breakoff and Retention Mechanism
This novel core break-off and retention mechanism consists of a scoring dawg controlled by a set of two tubes (a drill tube and an inner tube). The drill tube and the inner tube have longitudinal concentric holes. The solution can be implemented in an eccentric tube configuration as well where the tubes have eccentric longitudinal holes. The inner tube presents at the bottom two control surfaces for controlling the orientation of the scoring dawg. The drill tube presents a sunk-in profile on the inside of the wall for housing the scoring dawg. The inner tube rotation relative to the drill tube actively controls the orientation of the scoring dawg and hence its penetration and retrieval from the core. The scoring dawg presents a shaft, two axially spaced arms, and a tooth. The two arms slide on the control surfaces of the inner tube. The tooth, when rotated, can penetrate or be extracted from the core. During drilling, the two tubes move together maintaining the scoring dawg completely outside the core. After the desired drilling depth has been reached the inner tube is rotated relative to the drill tube such that the tooth of the scoring dawg moves toward the central axis. By rotating the drill tube, the scoring dawg can score the core and so reduce its cross sectional area. The scoring dawg can also act as a stress concentrator for breaking the core in torsion or tension. After breaking the core, the scoring dawg can act as a core retention mechanism. For scoring, it requires the core to be attached to the rock. If the core is broken, the dawg can be used as a retention mechanism. The scoring dawg requires a hard-tip insert like tungsten carbide for scoring hard rocks. The relative rotation of the two tubes can be controlled manually or by an additional actuator. In the implemented design solution the bit rotation for scoring was in the same direction as the drilling. The device was tested for limestone cores and basalt cores. The torque required for breaking the 10-mm diameter limestone cores was 5 to 5.8 lb-in. (0.56 to 0.66 N-m)
Accelerating Bayesian hierarchical clustering of time series data with a randomised algorithm
We live in an era of abundant data. This has necessitated the development of new and innovative statistical algorithms to get the most from experimental data. For example, faster algorithms make practical the analysis of larger genomic data sets, allowing us to extend the utility of cutting-edge statistical methods. We present a randomised algorithm that accelerates the clustering of time series data using the Bayesian Hierarchical Clustering (BHC) statistical method. BHC is a general method for clustering any discretely sampled time series data. In this paper we focus on a particular application to microarray gene expression data. We define and analyse the randomised algorithm, before presenting results on both synthetic and real biological data sets. We show that the randomised algorithm leads to substantial gains in speed with minimal loss in clustering quality. The randomised time series BHC algorithm is available as part of the R package BHC, which is available for download from Bioconductor (version 2.10 and above) via http://bioconductor.org/packages/2.10/bioc/html/BHC.html. We have also made available a set of R scripts which can be used to reproduce the analyses carried out in this paper. These are available from the following URL. https://sites.google.com/site/randomisedbhc/
System for Packaging Planetary Samples for Return to Earth
A system is proposed for packaging material samples on a remote planet (especially Mars) in sealed sample tubes in preparation for later return to Earth. The sample tubes (Figure 1) would comprise (1) tubes initially having open tops and closed bottoms; (2) small, bellows-like collapsible bodies inside the tubes at their bottoms; and (3) plugs to be eventually used to close the tops of the tubes. The top inner surface of each tube would be coated with solder. The side of each plug, which would fit snugly into a tube, would feature a solder-filled ring groove. The system would include equipment for storing, manipulating, filling, and sealing the tubes. The containerization system (see Figure 2) will be organized in stations and will include: the storage station, the loading station, and the heating station. These stations can be structured in circular or linear pattern to minimize the manipulator complexity, allowing for compact design and mass efficiency. The manipulation of the sample tube between stations is done by a simple manipulator arm. The storage station contains the unloaded sample tubes and the plugs before sealing as well as the sealed sample tubes with samples after loading and sealing. The chambers at the storage station also allow for plug insertion into the sample tube. At the loading station the sample is poured or inserted into the sample tube and then the tube is topped off. At the heating station the plug is heated so the solder ring melts and seals the plug to the sample tube. The process is performed as follows: Each tube is filled or slightly overfilled with sample material and the excess sample material is wiped off the top. Then, the plug is inserted into the top section of the tube packing the sample material against the collapsible bellowslike body allowing the accommodation of the sample volume. The plug and the top of the tube are heated momentarily to melt the solder in order to seal the tube
Direct and cytokine-mediated effects of albumin-fused growth hormone, TV-1106, on CYP enzyme expression in human hepatocytes in vitro
Some biologics can modulate cytokines that may lead to changes in expression of drugmetabolizing
enzymes and cause drug-drug interactions (DDI). DDI potential of TV-
1106—an albumin-fused growth hormone (GH)—was investigated. In this study, human
blood was exposed to recombinant human growth hormone (rhGH) or TV-1106, followed
by isolation of the plasma and its application to human hepatocytes. While the
treatment of blood with rhGH increased multiple cytokines, treatment of blood with
TV-1106 had no effect on any of the nine cytokines tested. The interleukin (IL)-6 concentration
was higher in the rhGH then in the TV-1106-treated plasma (P < .05). While
rhGH had little or no effect on CYP1A2 or CYP2C19 mRNA but increased CYP3A4
mRNA twofold, TV-1106 had little or no effect on cytochrome P450 (CYP) mRNAs in
hepatocytes. Although the plasma from rhGH-treated blood lowered CYP1A2 activity,
the TV-1106 plasma had no effect on CYP activities. The CYP1A2 activity was lower in
the rhGH- then in the TV-1106-plasma treated hepatocytes (P < .05). The results indicated
that fusing GH with albumin made TV-1106 an unlikely participant of CYP1A2,
CYP2C19 or CYP3A4-facilitated, direct or cytokine-driven DDI.The authors would like to thank scientists in the Scientific Operations
at Sekisui XenoTech for their technical assistance
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