Influence of M-phase chromatin on the anisotropy of microtubule asters

In many eukaryotic cells going through M-phase, a bipolar spindle is formed by microtubules nucleated from centrosomes. These microtubules, in addition to being "captured" by kinetochores, may be stabilized by chromatin in two different ways: short-range stabilization effects may affect microtubules in close contact with the chromatin, while long-range stabilization effects may "guide" microtubule growth towards the chromatin (e.g., by introducing a diffusive gradient of an enzymatic activity that affects microtubule assembly). Here, we use both meiotic and mitotic extracts from Xenopus laevis eggs to study microtubule aster formation and microtubule dynamics in the presence of chromatin. In "low-speed" meiotic extracts, in the presence of salmon sperm chromatin, we find that short-range stabilization effects lead to a strong anisotropy of the microtubule asters. Analysis of the dynamic parameters of microtubule growth show that this anisotropy arises from a decrease in the catastrophe frequency, an increase in the rescue frequency and a decrease in the growth velocity. In this system we also find evidence for long-range "guidance" effects, which lead to a weak anisotropy of the asters. Statistically relevant results on these long-range effects are obtained in "high-speed" mitotic extracts in the presence of artificially constructed chromatin stripes. We find that aster anisotropy is biased in the direction of the chromatin and that the catastrophe frequency is reduced in its vicinity. In this system we also find a surprising dependence of the catastrophe and the rescue frequencies on the length of microtubules nucleated from centrosomes: the catastrophe frequency increase and the rescue frequency decreases with microtubule length

Equivariant Poincar\'e series of filtrations and topology

Earlier, for an action of a finite group $G$ on a germ of an analytic variety, an equivariant $G$-Poincar\'e series of a multi-index filtration in the ring of germs of functions on the variety was defined as an element of the Grothendieck ring of $G$-sets with an additional structure. We discuss to which extend the $G$-Poincar\'e series of a filtration defined by a set of curve or divisorial valuations on the ring of germs of analytic functions in two variables determines the (equivariant) topology of the curve or of the set of divisors

Lipoleiomyoma of the peritoneum

Lipoleiomyomas are rare, mixed mesenchymal tumors composed of adipose and smooth muscle cells. They usually arise from the uterus, with extrauterine tumors being extremely rare. The imaging and gross appearance is similar to other tumors with these constituents. Recognition of this rare and benign tumor is of great importance, in order to avoid erroneous diagnosis. We present a case of an extrauterine lipoleiomyoma with minimal amounts of fat, only identified by MRI. The extrauterine location was highlighted by multiplanar MRI, and the presence of a capsule suggested a benign tumor

Gold dimer in neon: an absorption and fluorescence study

We report for the first time the absorption and fluorescence spectra of gold dimers in a neon matrix. The dimer absorption spectra show the A ← X transition predicted from measurements in the gas phase and not observed so far in a matrix, as well as the so-called B ← X and C ← X transitions. Fluorescence measurements on the atom reveal new emission lines at 1.97, 3.59 and 4.09eV that can be assigned to the 2P1/2 → 2D3/2, 2P1/2 → 2D5/2 and the 2P3/2 → 2D5/2 transitions. For the dimer, excitation of both A and B state results in distinct emission spectra with vibrational structur

Mucinous cystadenoma of the appendix

A cystic mass in the right iliac fossa of an asymptomatic patient

Fair Loss-Tolerant Quantum Coin Flipping

Coin flipping is a cryptographic primitive in which two spatially separated players, who in principle do not trust each other, wish to establish a common random bit. If we limit ourselves to classical communication, this task requires either assumptions on the computational power of the players or it requires them to send messages to each other with sufficient simultaneity to force their complete independence. Without such assumptions, all classical protocols are so that one dishonest player has complete control over the outcome. If we use quantum communication, on the other hand, protocols have been introduced that limit the maximal bias that dishonest players can produce. However, those protocols would be very difficult to implement in practice because they are susceptible to realistic losses on the quantum channel between the players or in their quantum memory and measurement apparatus. In this paper, we introduce a novel quantum protocol and we prove that it is completely impervious to loss. The protocol is fair in the sense that either player has the same probability of success in cheating attempts at biasing the outcome of the coin flip. We also give explicit and optimal cheating strategies for both players.Comment: 12 pages, 1 figure; various minor typos corrected in version

Intercept-resend attacks in the Bennett-Brassard 1984 quantum key distribution protocol with weak coherent pulses

Unconditional security proofs of the Bennett-Brassard protocol of quantum key distribution have been obtained recently. These proofs cover also practical implementations that utilize weak coherent pulses in the four signal polarizations. Proven secure rates leave open the possibility that new proofs or new public discussion protocols obtain larger rates over increased distance. In this paper we investigate limits to error rate and signal losses that can be tolerated by future protocols and proofs.Comment: 11 pages, 3 figures. Version accepted for publication in Phys. Rev.

(Contravariant) Koszul duality for DG algebras

A DG algebras $A$ over a field $k$ with $H(A)$ connected and $H_{<0}(A)=0$ has a unique up to isomorphism DG module $K$ with $H(K)\cong k$. It is proved that if $H(A)$ is degreewise finite, then RHom_A(?,K): D^{df}_{+}(A)^{op} \equiv D_{df}^{+}}(RHom_A(K,K)) is an exact equivalence of derived categories of DG modules with degreewise finite-dimensional homology. It induces an equivalences of $D^{df}_{b}(A)^{op}$ and the category of perfect DG $RHom_A(K,K)$-modules, and vice-versa. Corresponding statements are proved also when $H(A)$ is simply connected and $H^{<0}(A)=0$.Comment: 33 page

Effect of extrusion on the trypsin inhibitors activity and digestibility of the raw soybean in dogs determined by the regression, substitution, and difference methods.

The lack of standardized methodologies to evaluate an ingredient?s digestibility in dogs contributes to the poor information about it. This is particularly important in protein sources, such as soybean, because dogs are carnivorous. There has been little investigation on the effect of pet food extrusion on the inactivation of trypsin inhibitors present in raw soybeans (RSB). Because of this, we aimed to evaluate the effect of extrusion on trypsin inhibitors and on the digestibility of RSB by the regression (REG), substitution (SUB), and difference (DIF) methods in dogs. Animals, material and methods: Six adult Beagle dogs were distributed in a Latin square design (6 x 6). The dogs were fed six extruded diets (single screw extruder) with increasing levels of RSB (0, 6, 12, 18, 24, and 30%) for a 5-day adaptation period followed by 5 days of total faecal collection per period (AAFCO, 2004). Trypsin inhibitors activity was determined in the diets before and after extrusion. The coefficients of total tract apparent digestibility (CTTAD) of nutrients and the metabolizable energy (ME) of the RSB were determined by the SUB (Matterson et al., 1965), REG, and DIF methods (Fan and Sauer, 1995). Data were submitted to regression and to analysis of variance and the means were compared by Tukey's test (P0.05). The ether extract CTTAD (0.891 to 0.910) and the ME (18.4 to 19.0 MJ/kg) of the diets increased linearly (P0.05) in the CTTAD and ME predicted by the three methods, nor between the variances of the methods. Conclusion: The single screw extrusion process of diets containing high levels of RSB does not completely inactivate the trypsin inhibitors. However, up to 12% of RSB can be used in extruded diets without compromising protein digestibility and faecal consistency of dogs. Greater inclusion levels of RSB reduce estimative errors of this ingredient digestibility. Although the three methods can be used to predict ingredients digestibility in dogs, the DIF and the SUB methods are more practical than the REG method, considering the utilization of only two diets (reference and test), while the REG method requires at least four diets