780 research outputs found
The Impatient May Use Limited Optimism to Minimize Regret
Discounted-sum games provide a formal model for the study of reinforcement
learning, where the agent is enticed to get rewards early since later rewards
are discounted. When the agent interacts with the environment, she may regret
her actions, realizing that a previous choice was suboptimal given the behavior
of the environment. The main contribution of this paper is a PSPACE algorithm
for computing the minimum possible regret of a given game. To this end, several
results of independent interest are shown. (1) We identify a class of
regret-minimizing and admissible strategies that first assume that the
environment is collaborating, then assume it is adversarial---the precise
timing of the switch is key here. (2) Disregarding the computational cost of
numerical analysis, we provide an NP algorithm that checks that the regret
entailed by a given time-switching strategy exceeds a given value. (3) We show
that determining whether a strategy minimizes regret is decidable in PSPACE
How universal is the one-particle Green's function of a Luttinger liquid?
The one-particle Green's function of the Tomonaga-Luttinger model for
one-dimensional interacting Fermions is discussed. Far away from the origin of
the plane of space-time coordinates the function falls off like a power law.
The exponent depends on the direction within the plane. For a certain form of
the interaction potential or within an approximated cut-off procedure the
different exponents only depend on the strength of the interaction at zero
momentum and can be expressed in terms of the Luttinger liquid parameters
and of the model at hand. For a more general
interaction and directions which are determined by the charge velocity
and spin velocity the exponents also depend on the
smoothness of the interaction at zero momentum and the asymptotic behavior of
the Green's function is not given by the Luttinger liquid parameters alone.
This shows that the physics of large space-time distances in Luttinger liquids
is less universal than is widely believed.Comment: 5 pages with 2 figure
Response modes and coordination in a traffic context, an experimental comparison of Chinese and German participants
This paper reports results of laboratory experiments about traffic behavior of participants with different cultural backgrounds. We conducted the minority game as an elementary traffic scenario in which human participants of a German and Chinese subject pool had to choose over 100 periods between a road A and a road B. In each period, the road which was chosen by the minority of players won, these participants got a payoff. The payoff in the majority group was 0. An important observation is that the number of road changes of a participant is negatively correlated with her cumulative payoff. The Chinese participants reacted differently to the payoffs of preceding periods than the German participants
Effects of Spin Fluctuations in Quasi-One-Dimensional Organic Superconductors
We study the electronic states of quasi-one-dimensional organic conductors
using the single band Hubbard model at half-filling. We treat the effects of
the on-site Coulomb interaction by the fluctuation-exchange (FLEX) method, and
calculate the phase diagram and physical properties. The calculated pressure
dependence of the Neel temperature coincides well with the experimental one. We
also show that a pseudogap is formed in the density of states near the chemical
potential and that d-wave superconductivity appears next to the
antiferromagnetic state. Moreover the NMR relaxation rate increases on cooling
in the low-temperature region.Comment: 4 pages, 5 figures, to apprear in J. Phys. Soc. Jp
Reassessing the Impact of High Performance Workplaces
High performance workplace practices were extolled as an efficient means to increase firm productivity. The empirical evidence is disputed, however. To assess the productivity effects of a broad variety of measures, we simultaneously account for both unobserved heterogeneity and endogeneity using establishment panel data for Germany. We show that increasing employee participation enhances firm productivity in Germany, whereas incentive systems do not foster productivity. Our results further indicate that firms with structural productivity problems tend to introduce organisational changes that increase employee participation whereas well performing firms are more likely to offer incentives
Non-Zero Sum Games for Reactive Synthesis
In this invited contribution, we summarize new solution concepts useful for
the synthesis of reactive systems that we have introduced in several recent
publications. These solution concepts are developed in the context of non-zero
sum games played on graphs. They are part of the contributions obtained in the
inVEST project funded by the European Research Council.Comment: LATA'16 invited pape
Genotyping of Bacillus cereus Strains by Microarray-Based Resequencing
The ability to distinguish microbial pathogens from closely related but nonpathogenic strains is key to understanding the population biology of these organisms. In this regard, Bacillus anthracis, the bacterium that causes inhalational anthrax, is of interest because it is closely related and often difficult to distinguish from other members of the B. cereus group that can cause diverse diseases. We employed custom-designed resequencing arrays (RAs) based on the genome sequence of Bacillus anthracis to generate 422 kb of genomic sequence from a panel of 41 Bacillus cereus sensu lato strains. Here we show that RAs represent a âone reactionâ genotyping technology with the ability to discriminate between highly similar B. anthracis isolates and more divergent strains of the B. cereus s.l. Clade 1. Our data show that RAs can be an efficient genotyping technology for pre-screening the genetic diversity of large strain collections to selected the best candidates for whole genome sequencing
Non-fermi-liquid single particle lineshape of the quasi-one-dimensional non-CDW metal Li_{0.9}Mo_{6}O_{17} : comparison to the Luttinger liquid
We report the detailed non-Fermi liquid (NFL) lineshape of the dispersing
excitation which defines the Fermi surface (FS) for quasi-one-dimensional
Li_{0.9}Mo_{6}O_{17}. The properties of Li_{0.9}Mo_{6}O_{17} strongly suggest
that the NFL behavior has a purely electronic origin. Relative to the
theoretical Luttinger liquid lineshape, we identify significant similarities,
but also important differences.Comment: 5 pages, 3 eps figure
Rapid Identification of Genetic Modifications in Bacillus anthracis Using Whole Genome Draft Sequences Generated by 454 Pyrosequencing
Background The anthrax letter attacks of 2001 highlighted the need for rapid identification of biothreat agents not only for epidemiological surveillance of the intentional outbreak but also for implementing appropriate countermeasures, such as antibiotic treatment, in a timely manner to prevent further casualties. It is clear from the 2001 cases that survival may be markedly improved by administration of antimicrobial therapy during the early symptomatic phase of the illness; i.e., within 3 days of appearance of symptoms. Microbiological detection methods are feasible only for organisms that can be cultured in vitro and cannot detect all genetic modifications with the exception of antibiotic resistance. Currently available immuno or nucleic acid-based rapid detection assays utilize known, organism-specific proteins or genomic DNA signatures respectively. Hence, these assays lack the ability to detect novel natural variations or intentional genetic modifications that circumvent the targets of the detection assays or in the case of a biological attack using an antibiotic resistant or virulence enhanced Bacillus anthracis, to advise on therapeutic treatments. Methodology/Principal Findings We show here that the Roche 454-based pyrosequencing can generate whole genome draft sequences of deep and broad enough coverage of a bacterial genome in less than 24 hours. Furthermore, using the unfinished draft sequences, we demonstrate that unbiased identification of known as well as heretofore-unreported genetic modifications that include indels and single nucleotide polymorphisms conferring antibiotic and phage resistances is feasible within the next 12 hours. Conclusions/Significance Second generation sequencing technologies have paved the way for sequence-based rapid identification of both known and previously undocumented genetic modifications in cultured, conventional and newly emerging biothreat agents. Our findings have significant implications in the context of whole genome sequencing-based routine clinical diagnostics as well as epidemiological surveillance of natural disease outbreaks caused by bacterial and viral agents
Apprenticeship Training in Germany â Investment or Productivity Driven?
The German dual apprenticeship system came under pressure in recent years because enterprises were not willing to offer a sufficient number of apprenticeship positions. A frequently made argument is that the gap could be closed if more firms would be willing to incur net costs during the training period. This paper investigates for the first time whether German enterprises on average indeed incur net costs during the apprenticeship period, i.e. if the impact of an increase in the share of apprentices on contemporary profits is negative. The paper uses the representative linked employer-employee panel data of the IAB (LIAB) and takes into account possible endogeneity of training intensity and unobserved heterogeneity in the profit estimation by employing panel system GMM methods. An increase in the share of apprentices has no effect on profits. This can be interpreted as a first indication that most establishments in Germany do not invest more in apprentices than their productivity effects during the apprenticeship period
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