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Biomedical subjects

A A Petrov

Publications and source records attributed to A A Petrov.

At least 19 recordsLinked to original sources
PubMed2003

B0-B(-)0 mixing beyond factorization in QCD sum rules.

We present a calculation of the B0-B(-)0 mixing matrix element in the framework of QCD sum rules for three-point functions. We compute alpha(s) corrections to a three-point function at the three-loop level in QCD perturbation theory, which allows one to extract the matrix element with next-to-leading order (NLO) accuracy. This calculation is imperative for a consistent evaluation of experimentally measured mixing parameters since the coefficient functions of the effective Hamiltonian for B0-B(-)0 mixing are known at NLO. We find that radiative corrections violate factorization at NLO; this violation is under full control and amounts to 10%. The resulting value of the B parameter is found to be B(B)(m(b))=1+0.1(PT)-0.05(non-PT).

Journal Article↗
PubMed1997

[The characteristics of the anesthesiological support for surgical interventions in patients earlier operated on the heart].

The article presents an analysis of the authors' experiences with anesthesiological maintenance of operations on patients after revascularization of the myocardium, implantation of permanent cardiostimulant and heart value prosthesis. Main risk factors responsible for severe complications were found to be congestive heart failure, myocardial infarction which took place 6 months before the operation, certain forms of arrhythmias, unstable stenocardia, pronounced stenosis of the aortic valve, age older than 70 years, diabetes mellitus. The comprehensive preoperative preparing, choice of the adequate methods of anesthesia and maintenance of the up-to-date intraoperative monitoring create the conditions for a less risk of the surgical treatment.

Anesthesia↗
PubMed1979

Short-term immobilization of healthy men: right ventricular function and metabolism during graded exercise.

Five healthy male volunteers were subjected to graded exercise tests on a bicycle ergometer (600 kpm/min for 8 minutes) with simultaneous catheterization of the right cardiac ventricle and radial artery, first before immobilization and them after five-day bed rest in the head-down posture (the foot bed end was elevated 4.5 degrees). After immobilization, during exercise the stroke index did not increase, the tachycardia was more marked, the indicators of right ventricular contractility increased [+ max dp/dt, mas (dp/dt) /P, --mas dp/dt], the arterial pressure decreased, and the lactic acid level in mixed venous blood rose. Possible causes of haemodynamic and metabolic alterations, occurring in healthy volunteers during graded exercise following short-term hypokinesis, are discussed.

Adult↗
PubMedDate not supplied

Experience with the Nidek MK-2000 microkeratome in 1,220 cases.

PURPOSE: To evaluate the performance of the Nidek MK-2000 microkeratome. METHODS: The Nidek MK-2000 microkeratome was used in 1,220 cases of LASIK with the Nidek EC-5000 excimer laser. Patients had a wide range of myopia (-0.75 to -25.00 D), hyperopia (+0.75 to +9.00 D) and/or astigmatism (-7.00 to +6.50 D). The flap was created with the 130-microm microkeratome plate for 859 eyes, and the 160-microm plate for 361 eyes. In 632 eyes, the 8.5-mm ring was used, and the 9.5-mm ring was used in 588 eyes. The flap hinge was placed nasally, superiorly, or inferiorly depending on the needs of the case. An easy external modification allowed us to gently increase and decrease the vacuum level and to perform the procedure using a low vacuum regimen, if necessary. RESULTS: The edges of the flaps and the corneal surface were of good quality in all eyes. No free flaps were noted. One case was aborted because of inappropriate flap formation in a patient with a large difference (6.50 D) in corneal curvature in two main meridians. This patient successfully underwent LASIK 1 month later, placing the flap hinge in the opposite direction. Small epithelial shrinkage was noted in 38 eyes. No other flap complications were noted. In all patients the flap diameter and thickness were close to that estimated by the manufacturer. The vacuum level was adequate and stable in all cases. CONCLUSION: The Nidek MK-2000 microkeratome was easy to use, predictable, and safe. However, we suggest a modification, adding an adjustable head movement to create wider hinge-to-center-of-pupil distance and an additional 9.0-mm suction ring.

Anthropometry↗