Biomedical subjects
Publications and source records attributed to V Engel.
We calculate the harmonic spectrum generated by a model HD molecule in a strong laser pulse. The unequal nuclear masses lead to the emission of even harmonics, i.e., photon frequencies which are even multiples of the laser frequency. The effect does not occur within the Born-Oppenheimer approximation. In the high-frequency region, the even harmonics are almost of the same order of magnitude as the odd ones.
We present quantum mechanical calculations of the electron and ion momentum distributions following double ionization of a one-dimensional helium atom by ultrashort laser pulses (780 nm) at various intensities. The two-electron momentum distributions exhibit a clear transition from nonsequential to sequential double ionization. We provide strong evidence that rescattering is responsible for nonsequential ionization by calculating the momentum spectrum of the He2+ recoil ions-which we find in excellent agreement with recent experiments-and by analyzing the electronic center-of-mass motion via Wigner transforms.
Many elementary chemical and physical processes such as the breaking of a chemical bond or the vibrational motion of atoms within a molecule take place on a femtosecond (fs = 10(-15)s) or picosecond (ps = 10(-12)s) time scale. It is now possible to monitor these events as a function of time with temporal resolution well below 100 fs. This capability is based on the pump-probe technique where one optical pulse triggers a reaction and a second delayed optical pulse probes the changes that ensue. To illustrate this capability, the dynamics of ligand motion within a protein are presented. Moving beyond casual observation of a reaction to active control of its outcome requires additional experimental and theoretical effort. To illustrate the concept of control, the effect of optical pulse duration on the vibrational dynamics of a tri-atomic molecule are discussed. The experimental and theoretical resources currently available are poised to make the dream of reaction control a reality for certain molecular systems.
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Between 1970 and 1993 29 fractures of the intercondylar eminence were seen in children with almost the same number of cases showing no or minor displacement as those requiring open reduction for major dislocation. Combined knee injury must be suspected the higher the patient's age and the more pronounced the displacement of the fragment. Magnetic resonance imaging (MRI) has gained diagnostic predominance. Arthroscopy remains important for surgical management, especially of associated meniscus and cartilage damage. Early puncture of hemarthrosis is essential. Closed management is the therapy for nondisplaced fragments or those with bone contact or only tuberculum fractures--while displaced fragments require operative reduction. Arthroscopy-aided wire fixation is the preferred technique, followed by open reduction using absorbable suture material (wire in special cases). Traction screws should be used only in older children with large fragments. Our series show good late results because occasional function impairment with knee instability tends to normalize with growth. Corrective orthopedic procedures--if at all--are required only for juveniles or adults.
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It is reported on the experiment to describe group-dynamic processes in the macrogroup, taking into particular consideration the comparison of open and closed microgroups. The examination of 76 sessions of macrogroups in a psychotherapeutic inpatient institution with 2 open and 2 closed microgroups has the following results: 1. The prevalence of the open groups in activity; 2. a correlative dependence of the alpha- and beta-position as group function 3. a two-phase development of the closed groups in the macrogroup.
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A 3-year-old boy developed several subcutaneous nodular lesions on his right arm. Based on the histological examination of one of these nodules furunculosis was suspected and cefuroxime was tentatively given. However, acid-fast bacilli were then detected in the tissue specimen and a few colonies of acid fast, gram-positive rods grew on blood agar. Definitive species diagnosis (Mycobacterium marinum) was rapidly achieved by automated sequencing of amplified 16S-rDNA and antimicrobial therapy was adjusted according to the available literature. After 3 weeks of treatment with clarithromycin, rifampicin and protionamid regression of the nodular lesions was evident.