Exporting by Latvian companies: Vitality, drivers of success, and challenges

This paper sheds light on Latvian exporters - how active they are, what challenges they face, what makes them succeed or fail. Our study draws on a survey of 503 medium-sized Latvian companies. We find that most medium-sized Latvian companies are exporters (either directly or indirectly) and for a typical exporting company, export turnover constitutes more than half of its total turnover. Exporting companies tend to be larger, younger and faster growing than their non-exporting counterparts. They pay higher average wages, consistent with the no-tion that they have higher labour productivity or utilise more skilled labour on average. For a typical company, export activity has been stable over the past five years, with zero growth in export turnover and an average increase of one additional export destination; however, there is wide dispersion in export growth and success among exporting companies. Success-ful exporters tend to be larger, with higher productivity growth and greater innovativeness, proactiveness and risk taking, i.e., stronger entrepreneurial orientation. The main obstacle preventing non-exporters from commencing exporting is lack of international competitive-ness. This is also the main reason why companies discontinue exporting, and should be the focus of policy aimed at promoting exporting

Volumes and Integer Points of Multi-Index Transportation Polytopes.

Counting the integer points of transportation polytopes has important applications in statistics for tests of statistical significance, as well as in several applications in combinatorics. In this dissertation, we derive asymptotic formulas for the number of integer and binary integer points in a wide class of multi-index transportation polytopes. A simple closed form approximation is given as the size of the corresponding arrays goes to infinity. A formula for the volume of $4$-index transportation polytopes is also given. We follow the approach of Barvinok and Hartigan to estimate the quantities through a type of local Central Limit Theorem. By carefully estimating eigenvalues and eigenvectors of certain quadratic forms, we are able to prove strong concentration results for the corresponding multivariate Gaussian random variables. We also estimate correlations between linear functions of Gaussian random variables to produce concentration results for the distribution of certain exponential functions. Combined, these techniques allow us to give a complete accounting of the integrals of several functions that are key to estimating the number of integer or binary integer points in multi-index transportation polytopes. As an additional result, we transform a standard concentration of measure on the sphere argument to a concentration result for Gaussian measures whose quadratic forms contain several small eigenvalues, allowing a similar calculation for the volume of multi-index transportation polytopes.PHDMathematicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111456/1/dputnins_1.pd

Sex, drugs, and bitcoin:How much illegal activity Is financed through cryptocurrencies?

© The Author(s) 2019. Cryptocurrencies are among the largest unregulated markets in the world. We find that approximately one-quarter of bitcoin users are involved in illegal activity.We estimate that around 76 billion of illegal activity per year involve bitcoin (46% of bitcoin transactions), which is close to the scale of the U.S. and European markets for illegal drugs. The illegal share of bitcoin activity declines with mainstream interest in bitcoin and with the emergence of more opaque cryptocurrencies. The techniques developed in this paper have applications in cryptocurrency surveillance. Our findings suggest that cryptocurrencies are transforming the black markets by enabling black e-commerce. (JEL G18, O31, O32, O33)

Successful Bacteriophage-Antibiotic Combination Therapy against Multidrug-Resistant Pseudomonas aeruginosa Left Ventricular Assist Device Driveline Infection

Publisher Copyright: © 2023 by the authors.There is considerable interest in the use of bacteriophages (phages) to treat Pseudomonas aeruginosa infections associated with left ventricular assist devices (LVADs). These infections are often challenging to manage due to high rates of multidrug resistance and biofilm formation, which could potentially be overcome with the use of phages. We report a case of a 54-year-old man with relapsing multidrug-resistant P. aeruginosa LVAD driveline infection, who was treated with a combination of two lytic antipseudomonal phages administered intravenously and locally. Treatment was combined with LVAD driveline repositioning and systemic antibiotic administration, resulting in a successful outcome with clinical cure and eradication of the targeted bacteria. However, laboratory in vitro models showed that phages alone could not eradicate biofilms but could prevent biofilm formation. Phage-resistant bacterial strains evolved in biofilm models and showed decreased susceptibility to the phages used. Further studies are needed to understand the complexity of phage resistance and the interaction of phages and antibiotics. Our results indicate that the combination of phages, antibiotics, and surgical intervention can have great potential in treating LVAD-associated infections. More than 21 months post-treatment, our patient remains cured of the infection.publishersversionPeer reviewe

Emended description of Actinomyces naeslundii and descriptions of Actinomyces oris sp. nov. and Actinomyces johnsonii sp. nov., previously identified as Actinomyces naeslundii genospecies 1, 2 and WVA 963

Actinomyces naeslundii is an important early colonizer in the oral biofilm and consists of three genospecies (1, 2 and WVA 963) which cannot be readily differentiated using conventional phenotypic testing or on the basis of 16S rRNA gene sequencing. We have investigated a representative collection of type and reference strains and clinical and oral isolates (n=115) and determined the partial gene sequences of six housekeeping genes (atpA, rpoB, pgi, metG, gltA and gyrA). These sequences identified the three genospecies and differentiated them from Actinomyces viscosus isolated from rodents. The partial sequences of atpA and metG gave best separation of the three genospecies. A. naeslundii genospecies 1 and 2 formed two distinct clusters, well separated from both genospecies WVA 963 and A. viscosus. Analysis of the same genes in other oral Actinomyces species (Actinomyces gerencseriae, A. israelii, A. meyeri, A. odontolyticus and A. georgiae) indicated that, when sequence data were obtained, these species each exhibited <90 % similarity with the A. naeslundii genospecies. Based on these data, we propose the name Actinomyces oris sp. nov. (type strain ATCC 27044T =CCUG 34288T) for A. naeslundii genospecies 2 and Actinomyces johnsonii sp. nov. (type strain ATCC 49338T =CCUG 34287T) for A. naeslundii genospecies WVA 963. A. naeslundii genospecies 1 should remain as A. naeslundii sensu stricto, with the type strain ATCC 12104T =NCTC 10301T =CCUG 2238T

A new chemical formulation for control of dental unit water line contamination: An 'in vitro' and clinical 'study'

BACKGROUND: Water delivered by dental units during routine dental practice is highly contaminated. The aim of this study is to evaluate the efficacy of a new chemical solution flushed through Dental Unit Water Lines (DUWL) for the control of contamination inside dental units. MATERIALS AND METHODS: Six old dental units equipped with a device designed to automatically flush disinfecting solutions through the water system (Castellini Autosteril) were selected. Water samples from DUWL effluents were collected in each dental unit for 10 randomly selected days, before and after a 5 minute DUWL disinfecting cycle with TetraAcetylEthileneDiamine (TAED) and persalt (Ster4spray produced by Farmec spa, and distributed by Castellini spa). Water samples were plated in R2A Agar and cultured at room temperature for 7 days, and the total number of heterotrophic microorganisms counted and expressed in Log(10) CFU/mL A general linear model was fitted and multiple regression ANOVA for repeated measures was used for the statistical analysis. RESULTS: The mean contamination in DUWL effluent at baseline was 5.45 ± 0.35 CFU/mL (range 4.79 to 5.93 CFU/mL). When water samples were tested "in vitro" against the chemical, no growth of heterotrophic bacteria was detected after a 5 minute contact in any of the water samples tested. After undergoing a 5 minute disinfecting cycle with the chemical, DUWL mean contamination in water effluents was 2.01 ± 0.32 CFU/mL (range 1.30 to 2.74 CFU/mL) (significant difference with respect to baseline). CONCLUSIONS: An inbetween patient disinfecting procedure consisting of flushing DUWL with TAED and persalt equivalent to 0.26% peracetic acid could be useful in routine dental practice for cross-contamination control

To pay or not to pay? Business owners’ tax morale:testing a neo-institutional framework in a transition environment

In order to understand how the environment influences business owner/managers’ attitudes towards tax morale, we build a theoretical model based on a neo-institutionalist framework. Our model combines three complementary perspectives on institutions—normative, cultural–cognitive and regulatory–instrumental. This enables a broader understanding of factors that influence business owner–managers’ attitudes towards tax evasion. We test the resulting hypotheses using regression analysis on survey data on business owner/managers in Latvia—a transition country, which has undergone massive institutional changes since it was part of the Soviet Union over 25 years ago. We find that legitimacy of the tax authorities and the government (normative dimension), feeling of belonging to the nation (cultural–cognitive dimension) and perceptions of the risk and severity of punishment (regulatory–instrumental dimension) are all associated with higher tax morale for business owners and managers