Algebraic Results on Quantum Automata

We use tools from the algebraic theory of automata to investigate the class of languages recognized by two models of Quantum Finite Automata (QFA): Brodsky and Pippenger's end-decisive model (which we call BPQFA) and a new QFA model (which we call LQFA) whose definition is motivated by implementations of quantum computers using nucleo-magnetic resonance (NMR). In particular, we are interested in LQFA since NMR was used to construct the most powerful physical quantum machine to date. We give a complete characterization of the languages recognized by LQFA and by Boolean combinations of BPQFA. It is a surprising consequence of our results that LQFA and Boolean combinations of BPQFA are equivalent in language recognition power.     

Protective Effects of Meldonium in Experimental Models of Cardiovascular Complications with a Potential Application in COVID-19

Right ventricular (RV) and left ventricular (LV) dysfunction is common in a significant number of hospitalized coronavirus disease 2019 (COVID-19) patients. This study was conducted to assess whether the improved mitochondrial bioenergetics by cardiometabolic drug meldonium can attenuate the development of ventricular dysfunction in experimental RV and LV dysfunction models, which resemble ventricular dysfunction in COVID-19 patients. Effects of meldonium were assessed in rats with pulmonary hypertension-induced RV failure and in mice with inflammation-induced LV dysfunction. Rats with RV failure showed decreased RV fractional area change (RVFAC) and hypertrophy. Treatment with meldonium attenuated the development of RV hypertrophy and increased RVFAC by 50%. Mice with inflammation-induced LV dysfunction had decreased LV ejection fraction (LVEF) by 30%. Treatment with meldonium prevented the decrease in LVEF. A decrease in the mitochondrial fatty acid oxidation with a concomitant increase in pyruvate metabolism was noted in the cardiac fibers of the rats and mice with RV and LV failure, respectively. Meldonium treatment in both models restored mitochondrial bioenergetics. The results show that meldonium treatment prevents the development of RV and LV systolic dysfunction by enhancing mitochondrial function in experimental models of ventricular dysfunction that resembles cardiovascular complications in COVID-19 patients.     

How Low can Approximate Degree and Quantum Query Complexity be for Total Boolean Functions?

It has long been known that any Boolean function that depends on n input variables has both degree and exact quantum query complexity of Ω(log n), and that this bound is achieved for some functions. In this paper, we study the case of approximate degree and bounded-error quantum query complexity. We show that for these measures, the correct lower bound is Ω(log n/ log  log n), and we exhibit quantum algorithms for two functions where this bound is achieved.     

Thermo-Electric Motions and Structures Generated by Static Magnetic Fields During the Solidification of Metallic Alloys

Thermo-electric currents in the presence of static magnetic fields generate significant electromagnetic forces(TEM forces).The thermo-electric currents are due to the Seebeck effect when temperature gradients exist in the material.Those forces may produce various phenomena like pumping,stirring in liquid metals as well as solid motions,stresses in the solid metal.Those effects may be encountered especially during the solidification of metallic materials because of the existence of significant temperature gradients.In liquid metals the application of a static magnetic field enhances TEM convection at moderate intensity but also damps it when it is strong enough.This means that there exists a maximum of the convection which occurs when the Hartmann layers are comparable to the considered length scale.However,the smaller the length scales are(for example when primary or secondary dendrite arm spacings are considered),the higher the magnetic field strength which is needed to damp the TEM convection.So far,many solidification experiments on various types of alloys(e.g.,Sn-Pb,Al-Cu,Al-Si,Al-Ni etc.)have been carried out.The experiments have shown that TEM convection occurs both in the liquid bulk but also in the deep mushy zone.TEM convection may strongly influence the meso-macrosegregation patterns,the solidification structures and the grain boundaries leading to the striking grain boundary structure of the mushy zone.The flow pattern and accordingly the segregations may be controlled by changing the orientation of the applied magnetic field,i.e.,axial or transverse.We have shown that very high magnetic field strengths,up to 16 T,are needed to damp the TEM convection.Heuristic numerical and analytical investigations show that the TEM force density is very important in the liquid,but can be even more important in the solid.Indeed,for high Hartmann number,the electric currents are confined in a small skin layer near the solid boundaries leading to a decay of the flow.However,the situation is different in the solid,since     

Ordinal mind change complexity of language identification

The approach of ordinal mind change complexity, introduced by Freivalds and Smith, uses (notations for) constructive ordinals to bound the number of mind changes made by a learning machine. This approach provides a measure of the extent to which a learning machine has to keep revising its estimate of the number of mind changes it will make before converging to a correct hypothesis for languages in the class being learned. Recently, this notion, which also yields a measure for the difficulty of learning a class of languages, has been used to analyze the learnability of rich concept classes.

The present paper further investigates the utility of ordinal mind change complexity. It is shown that for identification from both positive and negative data and n 1, the ordinal mind change complexity of the class of languages formed by unions of up to n + 1 pattern languages is only ω ×₀ notn(n) (where notn(n) is a notation for n, ω is a notation for the least limit ordinal and ×₀ represents ordinal multiplication). This result nicely extends an observation of Lange and Zeugmann that pattern languages can be identified from both positive and negative data with 0 mind changes.

Existence of an ordinal mind change bound for a class of learnable languages can be seen as an indication of its learning “tractability”. Conditions are investigated under which a class has an ordinal mind change bound for identification from positive data. It is shown that an indexed family of languages has an ordinal mind change bound if it has finite elasticity and can be identified by a conservative machine. It is also shown that the requirement of conservative identification can be sacrificed for the purely topological requirement ofM-finite thickness. Interaction between identification by monotonic strategies and existence of ordinal mind change bound is also investigated.     

Syntheses of Coumarins in Environmentally Friendly Ionics Liquids

Syntheses of 3-substituted coumarins by the condensation reaction of salicylaldehyde with activated methylene compounds （ethyl cyanoacetate, malonic acid） are discussed in media of ionic liquids--（2-hydroxyethyl）ammonium carboxylates （formates, acetates, lactates） without utilization of any other catalysts. The dependence of yields of the reaction product is investigated on the structure of ionic liquids （their cations, anions, total polarity and pseudo-pH values）. 3-Substituted coumarins are prepared in high yields in media of these environmentally friendly ionic liquids which serve simultaneously as reaction media and as catalysts. The mentioned ionic liquids are prepared by reactions of corresponding hydroxyethyl-amines with carboxylic acids, and their quantitative analyses being made by potentiometric titration of ionic liquids with perchloric acid in 100% acetic acid.     

Wrist and tendon dynamics as contributory risk factors in work‐related musculoskeletal disorders

Many studies have shown that repetitive wrist motion is a major risk factor for work‐related musculoskeletal disorders (WMSDs). Specific contributory factors include wrist and tendon dynamics. The authors present recent methodological advances, epidemiological studies, and biomechanical models estimating the effects of wrist dynamics on internal tendon force as a theoretical basis for the risk of incurring a WMSD. These biomechanical models utilize either the reduction method or the optimization method to solve the indeterminate problem resulting from too many internal variables. Generally, the optimization methods show the best agreement with direct in vivo tendon force studies. For the models of pinch grips, the average ratio of tendon forces to external forces ranges from 1.8 to 3.5, while for direct tendon measurements, the ratio ranges from 1.73 to 7.92. Similarly, high contributions of flexor tendons for pinches and grasps are found in both the models and direct tendon measurements. These high tendon forces combined with wrist dynamics may be a significant factor in the development of WMSDs. © 2006 Wiley Periodicals, Inc. Hum Factors Man 16: 83–105, 2006.     

Electrochemical and optical properties of sputter deposited Ir–Ta and Ir oxide thin films

Addition of tantalum oxide has been investigated in order to improve the electrochromic properties of iridium oxide. Films of iridium–tantalum oxide and iridium oxide have been prepared and studied with regard to their optical and electrochemical properties. It can be seen that the addition of tantalum decreases the optical absorption coefficient and increases the ion diffusion coefficient. The change of properties is thought to be a result of the dilution of colouring iridium oxide with the better ion conducting tantalum oxide.