Contention Resolution with Heterogeneous Job Sizes

Abstract. We study the problem of contention resolution for differentsized jobs on a simple channel. When a job makes a run attempt, it learns only whether the attempt succeeded or failed. We first analyze binary exponential backoff, and show that it achieves a makespan of V2 Θ( logn) with high probability, where V is the total work of all n contending jobs. This bound is significantly larger than when jobs are constant sized. A variant of exponential backoff, however, achieves makespan O(V logV) with high probability. Finally, we introduce a new protocol, size-hashed backoff, specifically designed for jobs of multiple sizes that achieves makespan O(V log 3 logV). The error probability of the first two bounds is polynomially small in n and the latter is polynomially small in logV.

Computation with narrow CTCs

We examine some variants of computation with closed timelike curves (CTCs), where various restrictions are imposed on the memory of the computer, and the information carrying capacity and range of the CTC. We give full characterizations of the classes of languages recognized by polynomial time probabilistic and quantum computers that can send a single classical bit to their own past. Such narrow CTCs are demonstrated to add the power of limited nondeterminism to deterministic computers, and lead to exponential speedup in constant-space probabilistic and quantum computation. We show that, given a time machine with constant negative delay, one can implement CTC-based computations without the need to know about the runtime beforehand.Comment: 16 pages. A few typo was correcte

Implications of quantum automata for contextuality

We construct zero-error quantum finite automata (QFAs) for promise problems which cannot be solved by bounded-error probabilistic finite automata (PFAs). Here is a summary of our results: - There is a promise problem solvable by an exact two-way QFA in exponential expected time, but not by any bounded-error sublogarithmic space probabilistic Turing machine (PTM). - There is a promise problem solvable by an exact two-way QFA in quadratic expected time, but not by any bounded-error $o(\log \log n)$-space PTMs in polynomial expected time. The same problem can be solvable by a one-way Las Vegas (or exact two-way) QFA with quantum head in linear (expected) time. - There is a promise problem solvable by a Las Vegas realtime QFA, but not by any bounded-error realtime PFA. The same problem can be solvable by an exact two-way QFA in linear expected time but not by any exact two-way PFA. - There is a family of promise problems such that each promise problem can be solvable by a two-state exact realtime QFAs, but, there is no such bound on the number of states of realtime bounded-error PFAs solving the members this family. Our results imply that there exist zero-error quantum computational devices with a \emph{single qubit} of memory that cannot be simulated by any finite memory classical computational model. This provides a computational perspective on results regarding ontological theories of quantum mechanics \cite{Hardy04}, \cite{Montina08}. As a consequence we find that classical automata based simulation models \cite{Kleinmann11}, \cite{Blasiak13} are not sufficiently powerful to simulate quantum contextuality. We conclude by highlighting the interplay between results from automata models and their application to developing a general framework for quantum contextuality.Comment: 22 page

Nip1p associates with 40 S ribosomes and the Prt1p subunit of eukaryotic initiation factor 3 and is required for efficient translation initiation

Nip1p is an essential Saccharomyces cerevisiae protein that was identified in a screen for temperature conditional (ts) mutants exhibiting defects in nuclear transport. New results indicate that Nip1p has a primary role in translation initiation. Polysome profiles indicate that cells depleted of Nip1p and nip1-1 cells are defective in translation initiation, a conclusion that is supported by a reduced rate of protein synthesis in Nip1p- depleted cells. Nip1p cosediments with free 40 S ribosomal subunits and polysomal preinitiation complexes, but not with free or elongating 80 S ribosomes or 60 S subunits. Nip1p can be isolated in an about 670-kDa complex containing polyhistidine-tagged Prt1p, a subunit of translation initiation factor 3, by binding to Ni2+NTA-agarose beads in a manner completely dependent on the tagged form of Prt1p. The nip1-1 ts growth defect was suppressed by the deletion of the ribosomal protein, RPL46. Also, nip1-1 mutant cells are hypersensitive to paromomycin. These results suggest that Nip1p is a subunit of eukaryotic initiation factor 3 required for efficient translation initiation

Implications of Space-Time foam for Entanglement Correlations of Neutral Kaons

The role of $CPT$ invariance and consequences for bipartite entanglement of neutral (K) mesons are discussed. A relaxation of $CPT$ leads to a modification of the entanglement which is known as the $\omega$ effect. The relaxation of assumptions required to prove the $CPT$ theorem are examined within the context of models of space-time foam. It is shown that the evasion of the EPR type entanglement implied by $CPT$ (which is connected with spin statistics) is rather elusive. Relaxation of locality (through non-commutative geometry) or the introduction of decoherence by themselves do not lead to a destruction of the entanglement. So far we find only one model which is based on non-critical strings and D-particle capture and recoil that leads to a stochastic contribution to the space-time metric and consequent change in the neutral meson bipartite entanglement. The lack of an omega effect is demonstrated for a class of models based on thermal like baths which are generally considered as generic models of decoherence

Early magnetic resonance imaging and cognitive markers of hereditary cerebral amyloid angiopathy

FSW - Self-regulation models for health behavior and psychopathology - ou

Linking Distributive and Procedural Justice to Employee Engagement Through Social Exchange: A Field Study in India

Research linking justice perceptions to employee outcomes has referred to social exchange as its central theoretical premise. We tested a conceptual model linking distributive and procedural justice to employee engagement through social exchange mediators, namely, perceived organizational support and psychological contract, among 238 managers and executives from manufacturing and service sector firms in India. Findings suggest that perceived organizational support mediated the relationship between distributive justice and employee engagement, and both perceived organizational support and psychological contract mediated the relationship between procedural justice and employee engagement. Theoretical and practical implications with respect to organizational functions are discussed