Distribution and abundance of early life stages of squid (Illex argentinus) in the south-west Atlantic

A joint research cruise (Japan-Argentina-Uruguay) was carried out in the South-western Atlantic during August-September 1989 in order to study the winter-spawning and hatchery areas of Illex argentinus, and also the migration pattern of the juveniles towards the continental shelf. A few Rhynchoteuthion larvae were found in subtropical waters of the Brazil Current, next to the Brazil-Malvinas confluence, and in the frontal zone with shelf water, but never at temperatures below 14°C. Large numbers of juveniles found in subantarctic waters (6–10°C) on the shelf were probably migrating southward from their hatchery grounds following the zooplankton concentrations on which they were feeding

Uporedna analiza izoformi α-amilaze iz srednjeg creva larvi Cerambyx cerdo L. (Coleoptera: Cerambycidae) iz prirode i gajenih na veštačkoj podlozi

alpha-Amylase isoforms of Cerambyx cerdo larvae from the wild (ML and SL) and reared in the laboratory (ADL) were compared. Three amylase isoforms were presented in the SL and ML extracts while two isoforms were presented in the ADL according to zymogram after isoelectric focusing (IEF). All C. cerdo amylase isoforms were acidic proteins (pI lt 3.5). Seven amylase isoforms (ACC 1-7) from the midgut of C. cerdo larvae were found in the ML midgut extract, six in the SL extract, and four in the ADL extract according to native PAGE zymogram. The ADL amylase had the highest activity. All crude midgut extracts of C. cerdo larvae were fractionated on a Superose 12 HR column. The molecular mass of the ACC was estimated to be 34 kDa.Upoređene su izoforme α-amilaze larvi Cerambyx cerdo sakupljenih iz prirode (ML i SL) i gajenih na veštačkoj podlozi u laboratoriji (ADL). Zimogramskom detekcijom posle IEF-a po tri izoforme su detektovane u ML i SL ekstraktima, a u ADL dve izoforme. Sve amilazne izoforme iz C. cerdo su bile kisele (pI lt 3.5). Zimogramskom detekcijom posle nativne elektroforeze sedam izoformi je detektovano u ML ekstraktu, šest u SL ekstraktu i četiri u ADL ekstraktu. Najveća amilazna aktivnost je detektovana u ADL ekstraktu. Svi ekstrakti srednjih creva larvi C. cerdo su frakcionisani na koloni Superose 12 HR. Molekulska masa ACC-a je bila 34 kDa

Influenza-virus membrane fusion by cooperative fold-back of stochastically induced hemagglutinin intermediates

Influenza virus penetrates cells by fusion of viral and endosomal membranes catalyzed by the viral hemagglutinin (HA). Structures of the initial and final states of the HA trimer define the fusion endpoints, but do not specify intermediates. We have characterized these transitions by analyzing low-pH-induced fusion kinetics of individual virions and validated the analysis by computer simulation. We detect initial engagement with the target membrane of fusion peptides from independently triggered HAs within the larger virus-target contact patch; fusion then requires engagement of three or four neighboring HA trimers. Effects of mutations in HA indicate that withdrawal of the fusion peptide from a pocket in the pre-fusion trimer is rate-limiting for both events, but the requirement for cooperative action of several HAs to bring the fusing membranes together leads to a long-lived intermediate state for single, extended HA trimers. This intermediate is thus a fundamental aspect of the fusion mechanism

Geometrical approach to mutually unbiased bases

We propose a unifying phase-space approach to the construction of mutually unbiased bases for a two-qubit system. It is based on an explicit classification of the geometrical structures compatible with the notion of unbiasedness. These consist of bundles of discrete curves intersecting only at the origin and satisfying certain additional properties. We also consider the feasible transformations between different kinds of curves and show that they correspond to local rotations around the Bloch-sphere principal axes. We suggest how to generalize the method to systems in dimensions that are powers of a prime.Comment: 10 pages. Some typos in the journal version have been correcte

Kinetics of proton transport into influenza virions by the viral M2 channel

M2 protein of influenza A viruses is a tetrameric transmembrane proton channel, which has essential functions both early and late in the virus infectious cycle. Previous studies of proton transport by M2 have been limited to measurements outside the context of the virus particle. We have developed an in vitro fluorescence-based assay to monitor internal acidification of individual virions triggered to undergo membrane fusion. We show that rimantadine, an inhibitor of M2 proton conductance, blocks the acidification-dependent dissipation of fluorescence from a pH-sensitive virus-content probe. Fusion-pore formation usually follows internal acidification but does not require it. The rate of internal virion acidification increases with external proton concentration and saturates with a pKm of ~4.7. The rate of proton transport through a single, fully protonated M2 channel is approximately 100 to 400 protons per second. The saturating proton-concentration dependence and the low rate of internal virion acidification derived from authentic virions support a transporter model for the mechanism of proton transfer

Maximal Entanglement, Collective Coordinates and Tracking the King

Maximal entangled states (MES) provide a basis to two d-dimensional particles Hilbert space, d=prime $\ne 2$. The MES forming this basis are product states in the collective, center of mass and relative, coordinates. These states are associated (underpinned) with lines of finite geometry whose constituent points are associated with product states carrying Mutual Unbiased Bases (MUB) labels. This representation is shown to be convenient for the study of the Mean King Problem and a variant thereof, termed Tracking the King which proves to be a novel quantum communication channel. The main topics, notions used are reviewed in an attempt to have the paper self contained.Comment: 8. arXiv admin note: substantial text overlap with arXiv:1206.3884, arXiv:1206.035

An expectation value expansion of Hermitian operators in a discrete Hilbert space

We discuss a real-valued expansion of any Hermitian operator defined in a Hilbert space of finite dimension N, where N is a prime number, or an integer power of a prime. The expansion has a direct interpretation in terms of the operator expectation values for a set of complementary bases. The expansion can be said to be the complement of the discrete Wigner function. We expect the expansion to be of use in quantum information applications since qubits typically are represented by a discrete, and finite-dimensional physical system of dimension N=2^p, where p is the number of qubits involved. As a particular example we use the expansion to prove that an intermediate measurement basis (a Breidbart basis) cannot be found if the Hilbert space dimension is 3 or 4.Comment: A mild update. In particular, I. D. Ivanovic's earlier derivation of the expansion is properly acknowledged. 16 pages, one PS figure, 1 table, written in RevTe

Nonlocality without inequalities has not been proved for maximally entangled states

Two approaches to extend Hardy's proof of nonlocality without inequalities to maximally entangled states of bipartite two-level systems are shown to fail. On one hand, it is shown that Wu and co-workers' proof [Phys. Rev. A 53, R1927 (1996)] uses an effective state which is not maximally entangled. On the other hand, it is demonstrated that Hardy's proof cannot be generalized by the replacement of one of the four von Neumann measurements involved in the original proof by a generalized measurement to unambiguously discriminate between non-orthogonal states.Comment: 7 pages, 2 figures. To appear in Phys. Rev.

Exploring Apprenticeship Learning for Player Modelling in Interactive Narratives

In this paper we present an early Apprenticeship Learning approach to mimic the behaviour of different players in a short adaption of the interactive fiction Anchorhead. Our motivation is the need to understand and simulate player behaviour to create systems to aid the design and personalisation of Interactive Narratives (INs). INs are partially observable for the players and their goals are dynamic as a result. We used Receding Horizon IRL (RHIRL) to learn players' goals in the form of reward functions, and derive policies to imitate their behaviour. Our preliminary results suggest that RHIRL is able to learn action sequences to complete a game, and provided insights towards generating behaviour more similar to specific players.Comment: Extended Abstracts of the 2019 Annual Symposium on Computer-Human Interaction in Play (CHI Play

The Frobenius formalism in Galois quantum systems

Quantum systems in which the position and momentum take values in the ring ${\cal Z}_d$ and which are described with $d$-dimensional Hilbert space, are considered. When $d$ is the power of a prime, the position and momentum take values in the Galois field $GF(p^ \ell)$, the position-momentum phase space is a finite geometry and the corresponding `Galois quantum systems' have stronger properties. The study of these systems uses ideas from the subject of field extension in the context of quantum mechanics. The Frobenius automorphism in Galois fields leads to Frobenius subspaces and Frobenius transformations in Galois quantum systems. Links between the Frobenius formalism and Riemann surfaces, are discussed