75 research outputs found
Superconducting properties of the In-substituted topological crystalline insulator, SnTe
We report detailed investigations of the properties of a superconductor obtained by substituting In at the Sn site in the topological crystalline insulator (TCI), SnTe. Transport, magnetization and heat capacity measurements have been performed on crystals of SnInTe, which is shown to be a bulk superconductor with at ~K and at ~K. The upper and lower critical fields are estimated to be ~T and ~mT respectively, while indicates this material is a strongly type II superconductor
Isotropic-nematic phase equilibria in the Onsager theory of hard rods with length polydispersity
We analyse the effect of a continuous spread of particle lengths on the phase
behavior of rodlike particles, using the Onsager theory of hard rods. Our aim
is to establish whether ``unusual'' effects such as isotropic-nematic-nematic
(I-N-N) phase separation can occur even for length distributions with a single
peak. We focus on the onset of I-N coexistence. For a log-normal distribution
we find that a finite upper cutoff on rod lengths is required to make this
problem well-posed. The cloud curve, which tracks the density at the onset of
I-N coexistence as a function of the width of the length distribution, exhibits
a kink; this demonstrates that the phase diagram must contain a three-phase
I-N-N region.
Theoretical analysis shows that in the limit of large cutoff the cloud point
density actually converges to zero, so that phase separation results at any
nonzero density; this conclusion applies to all length distributions with
fatter-than-exponentail tails. Finally we consider the case of a Schulz
distribution, with its exponential tail. Surprisingly, even here the long rods
(and hence the cutoff) can dominate the phase behaviour, and a kink in the
cloud curve and I-N-N coexistence again result. Theory establishes that there
is a nonzero threshold for the width of the length distribution above which
these long rod effects occur, and shows that the cloud and shadow curves
approach nonzero limits for large cutoff, both in good agreement with the
numerical results.Comment: 20 pages, 13 figure
Non-conventional cement-based composites reinforced with vegetable fibers: A review of strategies to improve durability
Prime Focus Spectrograph - Subaru's future -
The Prime Focus Spectrograph (PFS) of the Subaru Measurement of Images and
Redshifts (SuMIRe) project has been endorsed by Japanese community as one of
the main future instruments of the Subaru 8.2-meter telescope at Mauna Kea,
Hawaii. This optical/near-infrared multi-fiber spectrograph targets cosmology
with galaxy surveys, Galactic archaeology, and studies of galaxy/AGN evolution.
Taking advantage of Subaru's wide field of view, which is further extended with
the recently completed Wide Field Corrector, PFS will enable us to carry out
multi-fiber spectroscopy of 2400 targets within 1.3 degree diameter. A
microlens is attached at each fiber entrance for F-ratio transformation into a
larger one so that difficulties of spectrograph design are eased. Fibers are
accurately placed onto target positions by positioners, each of which consists
of two stages of piezo-electric rotary motors, through iterations by using
back-illuminated fiber position measurements with a wide-field metrology
camera. Fibers then carry light to a set of four identical fast-Schmidt
spectrographs with three color arms each: the wavelength ranges from 0.38
{\mu}m to 1.3 {\mu}m will be simultaneously observed with an average resolving
power of 3000. Before and during the era of extremely large telescopes, PFS
will provide the unique capability of obtaining spectra of 2400
cosmological/astrophysical targets simultaneously with an 8-10 meter class
telescope. The PFS collaboration, led by IPMU, consists of USP/LNA in Brazil,
Caltech/JPL, Princeton, & JHU in USA, LAM in France, ASIAA in Taiwan, and
NAOJ/Subaru.Comment: 13 pages, 11 figures, submitted to "Ground-based and Airborne
Instrumentation for Astronomy IV, Ian S. McLean, Suzanne K. Ramsay, Hideki
Takami, Editors, Proc. SPIE 8446 (2012)
Inhibition of tumour growth by marimastat in a human xenograft model of gastric cancer: relationship with levels of circulating CEA
Inhibition of matrix metalloproteinases (MMPs) is an attractive approach to adjuvant therapy in the treatment of cancer. Marimastat is the first orally administered, synthetic MMP inhibitor to be evaluated, in this capacity, in the clinic. Measurement of the rate of change of circulating tumour antigens was used for evaluating biological activity and defining optimum dosage in the early clinical trials of marimastat. Although tumour antigen levels have been used in the clinical management of cancer for many years, they have not been validated as markers of disease progression. In order to investigate the relationship between the effects of marimastat on tumour growth and circulating tumour antigen levels, mice bearing the human gastric tumour, MGLVA1, were treated with marimastat. The MMP inhibitor exerted a significant therapeutic effect, reducing tumour growth rate by 48% (P = 0.0005), and increasing median survival from 19 to 30 days (P = 0.0001). In addition, carcinoembryonic antigen (CEA) levels were measured in serum samples from animals sacrificed at regular intervals, and correlated with excised tumour weight. It was shown that the natural log of the CEA concentration was linearly related to the natural log of the tumour weight and that treatment was not a significant factor in this relationship (P = 0.7). In conclusion, circulating CEA levels were not directly affected by marimastat, but did reflect tumour size. These results support the use of cancer antigens as markers of biological activity in early phase trials of non-cytotoxic anticancer agents. © 1999 Cancer Research Campaig
Fractionation of cellulose nanocrystals : enhancing liquid crystal ordering without promoting gelation
Colloids of electrically charged nanorods can spontaneously develop a fluid yet ordered liquid crystal phase, but this ordering competes with a tendency to form a gel of percolating rods. The threshold for ordering is reduced by increasing the rod aspect ratio, but the percolation threshold is also reduced with this change; hence, prediction of the outcome is nontrivial. Here, we show that by establishing the phase behavior of suspensions of cellulose nanocrystals (CNCs) fractionated according to length, an increased aspect ratio can strongly favor liquid crystallinity without necessarily influencing gelation. Gelation is instead triggered by increasing the counterion concentration until the CNCs lose colloidal stability, triggering linear aggregation, which promotes percolation regardless of the original rod aspect ratio. Our results shine new light on the competition between liquid crystal formation and gelation in nanoparticle suspensions and provide a path for enhanced control of CNC self-organization for applications in photonic crystal paper or advanced composites
Tales of migration from the global south. The civilized and uncivilized migrant in the narratives of La Tercera and El Mercurio
Migration is not a new phenomenon in Chile as the country has long seen migrants coming from Europe, the Middle East and Asia. Colonial views about race and ethnicity adopted by Latin Americans as part of their class structure (Quijano 2000) established an early differentiation between the “civilized migrant” and the “uncivilized migrant” among groups that arrived on Latin America shores. Chilean news media has echoes of this binary vision between the “civilized = good” migrant and the “uncivilized = bad” migrant. The chapter aims to uncover the narratives of the civilized and uncivilized migrant within the printed news media, particularly in the two major newspapers El Mercurio and La Tercera, by focusing on how these ideas frame the way in which they cover migration.Published versio
Complex Reorganization and Predominant Non-Homologous Repair Following Chromosomal Breakage in Karyotypically Balanced Germline Rearrangements and Transgenic Integration
We defined the genetic landscape of balanced chromosomal rearrangements at nucleotide resolution by sequencing 141 breakpoints from cytogenetically-interpreted translocations and inversions. We confirm that the recently described phenomenon of “chromothripsis” (massive chromosomal shattering and reorganization) is not unique to cancer cells but also occurs in the germline where it can resolve to a karyotypically balanced state with frequent inversions. We detected a high incidence of complex rearrangements (19.2%) and substantially less reliance on microhomology (31%) than previously observed in benign CNVs. We compared these results to experimentally-generated DNA breakage-repair by sequencing seven transgenic animals, and revealed extensive rearrangement of the transgene and host genome with similar complexity to human germline alterations. Inversion is the most common rearrangement, suggesting that a combined mechanism involving template switching and non-homologous repair mediates the formation of balanced complex rearrangements that are viable, stably replicated and transmitted unaltered to subsequent generations
Regulation of pH During Amelogenesis
During amelogenesis, extracellular matrix proteins interact with growing hydroxyapatite crystals to create one of the most architecturally complex biological tissues. The process of enamel formation is a unique biomineralizing system characterized first by an increase in crystallite length during the secretory phase of amelogenesis, followed by a vast increase in crystallite width and thickness in the later maturation phase when organic complexes are enzymatically removed. Crystal growth is modulated by changes in the pH of the enamel microenvironment that is critical for proper enamel biomineralization. Whereas the genetic bases for most abnormal enamel phenotypes (amelogenesis imperfecta) are generally associated with mutations to enamel matrix specific genes, mutations to genes involved in pH regulation may result in severely affected enamel structure, highlighting the importance of pH regulation for normal enamel development. This review summarizes the intra- and extracellular mechanisms employed by the enamel-forming cells, ameloblasts, to maintain pH homeostasis and, also, discusses the enamel phenotypes associated with disruptions to genes involved in pH regulation
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