813 research outputs found
Duodenal Carcinoma from a Duodenal Diverticulum Mimicking Pancreatic Carcinoma
An 81-year-old man was found to have a pancreatic head tumor on abdominal computed tomography (CT) performed during a follow-up visit for sigmoid colon cancer. The tumor had a diameter of 35mm on the CT scan and was diagnosed as pancreatic head carcinoma T3N0M0. The patient was treated with pylorus-preserving pancreaticoduodenectomy. Histopathological examination showed that the tumor had grown within a hollow structure, was contiguous with a duodenal diverticulum, and had partially invaded the pancreas. Immunohistochemistry results were as follows:CK7 negative, CK20 positive, CD10 negative, CDX2 positive, MUC1 negative, MUC2 positive, MUC5AC negative, and MUC6 negative. The tumor was diagnosed as duodenal carcinoma from the duodenal diverticulum. Preoperative imaging showed that the tumor was located in the head of the pancreas and was compressing the common bile duct, thus making it appear like pancreatic cancer. To the best of our knowledge, this is the second report of a case of duodenal carcinoma from a duodenal diverticulum mimicking pancreatic carcinoma
Antiferromagnetic spin correlations and pseudogap-like behavior in Ca(Fe1-xCox)2As2 studied by 75As nuclear magnetic resonance and anisotropic resistivity
We report As nuclear magnetic resonance (NMR) measurements of
single-crystalline Ca(FeCo)As ( = 0.023, 0.028, 0.033,
and 0.059) annealed at 350~C for 7 days. From the observation of a
characteristic shape of As NMR spectra in the stripe-type
antiferromagnetic (AFM) state, as in the case of = 0 ( = 170 K),
clear evidence for the commensurate AFM phase transition with the concomitant
structural phase transition is observed in = 0.023 ( = 106 K)
and = 0.028 ( = 53 K). Through the temperature dependence of the
Knight shifts and the nuclear spin lattice relaxation rates (1/), although
stripe-type AFM spin fluctuations are realized in the paramagnetic state as in
the case of other iron pnictide superconductors, we found a gradual decrease of
the AFM spin fluctuations below a crossover temperature which was nearly
independent of Co-substitution concentration, and is attributed to a
pseudogap-like behavior in the spin excitation spectra of these systems. The
feature finds correlation with features in the temperature-dependent
inter-plane resistivity, , but not with the in-plane resistivity
. The temperature evolution of anisotropic stripe-type AFM spin
fluctuations are tracked in the paramagnetic and pseudogap phases by the
1/ data measured under magnetic fields parallel and perpendicular to the
axis. Based on our NMR data, we have added a pseudogap-like phase to the
magnetic and electronic phase diagram of Ca(FeCo)As.Comment: 14 pages, 12 figures, accepted for publication in Phys. Rev.
Universally Composable Undeniable Signature
How to define the security of undeniable signature schemes is a challenging task. This paper presents two security definitions of undeniable signature schemes which are more useful or natural than the existing definition. It then proves their equivalence.
We first define the UC-security, where UC means universal composability. We next show that there exists a UC-secure undeniable signature scheme which does not satisfy the standard definition of security that has been believed to be adequate so far. More precisely, it does not satisfy the invisibility defined by \cite{DP96}. We then show a more adequate definition of invisibility which captures a wider class of (naturally secure) undeniable signature schemes.
We finally prove that the UC-security against non-adaptive adversaries is equivalent to this definition of invisibility and the strong unforgeability in \cF_{ZK}-hybrid model, where \cF_{ZK} is the ideal ZK functionality. Our result of equivalence implies that all the known proven secure undeniable signature schemes (including Chaum\u27s scheme) are UC-secure if the confirmation/disavowal protocols are both UC zero-knowledge
Characterization of TRPA channels in the starfish Patiria pectinifera: involvement of thermally activated TRPA1 in thermotaxis in marine planktonic larvae.
The vast majority of marine invertebrates spend their larval period as pelagic plankton and are exposed to various environmental cues. Here we investigated the thermotaxis behaviors of the bipinnaria larvae of the starfish, Patiria pectinifera, in association with TRPA ion channels that serve as thermal receptors in various animal species. Using a newly developed thermotaxis assay system, we observed that P. pectinifera larvae displayed positive thermotaxis toward high temperatures, including toward temperatures high enough to cause death. In parallel, we identified two TRPA genes, termed PpTRPA1 and PpTRPA basal, from this species. We examined the phylogenetic position, spatial expression, and channel properties of each PpTRPA. Our results revealed the following: (1) The two genes diverged early in animal evolution; (2) PpTRPA1 and PpTRPA basal are expressed in the ciliary band and posterior digestive tract of the larval body, respectively; and (3) PpTRPA1 is activated by heat stimulation as well as by known TRPA1 agonists. Moreover, knockdown and rescue experiments demonstrated that PpTRPA1 is involved in positive thermotaxis in P. pectinifera larvae. This is the first report to reveal that TRPA1 channels regulate the behavioral response of a marine invertebrate to temperature changes during its planktonic larval period
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