نتایج جستجو برای: escape frequency
تعداد نتایج: 513175 فیلتر نتایج به سال:
Introduction: Several mechanisms have been identified to result in escape of the Martian atmosphere. These mechanisms can be divided in two groups [1]: • Thermal escape or Jeans escape, which corresponds to the loss of atoms in the high energy tail of the energy distribution at the exobase. This mechanism is important only for the light species such as hydrogen or deuterium. • Non-thermal escap...
Intrahost simian immunodeficiency virus (SIV) evolution is marked by repeated viral escape from cytotoxic T-lymphocyte (CTLs) response. Typically, the first such CTL escape occurs in a matter of days, starting around the time of peak viral load. Many authors have developed methods to quantify the strength of CTL response by measuring the rate at which CTL escape occurs, but such methods usually...
Reviewing and integrating key concepts learning goals at the end of a biology course can be overwhelming to students instructors alike. Often end-of-term review sessions in preparation for final exams are heavily based on memorization, content coverage may favored over students’ deeper understanding fewer ideas. We developed exam virtual introductory evolution using an “escape room&...
The channel assignment problem is important in mobile telephone communication. Since the usable range of the frequency spectrum is limited, the optimal channel assignment problem has become increasingly important. In this paper, a new channel assignment algorithm using a modiied Hoppeld neural network is proposed. The channel assignment problem is formulated as an energy minimization problem th...
Hummingbirds are nature's masters of aerobatic manoeuvres. Previous research shows that hummingbirds and insects converged evolutionarily upon similar aerodynamic mechanisms and kinematics in hovering. Herein, we use three-dimensional kinematic data to begin to test for similar convergence of kinematics used for escape flight and to explore the effects of body size upon manoeuvring. We studied ...
The hippocampus, being sensitive to stress and glucocorticoids, plays significant roles in certain types of learning and memory. Therefore, the hippocampus is probably involved in the increasing drug use, drug seeking, and relapse caused by stress. We have studied the effect of stress with morphine on synaptic plasticity in the CA1 region of the hippocampus in vivo and on a delayed-escape parad...
The escape response to electrical or chemical stimulation of the dorsal periaqueductal gray matter (DPAG) has been associated with panic attacks. In order to explore the validity of the DPAG stimulation model for the study of panic disorder, we determined if the aversive consequences of the electrical or chemical stimulation of this midbrain area can be detected subsequently in the elevated T-m...
Bacteria adapt to environmental changes through high-frequency switches in expression of specific phenotypes. Localized hypermutation mediated by simple sequence repeats is an important mechanism of such phase variation (PV) in Neisseria meningitidis. Loss or gain of nucleotides in a poly(C) tract located in the reading frame results in switches in expression of lgtG and determines whether a gl...
The large diversity in MHC class I molecules in a population lowers the chance that a virus infects a host to which it is pre-adapted to escape the MHC binding of CTL epitopes. However, viruses can also lose CTL epitopes by escaping the monomorphic antigen processing components of the pathway (proteasome and TAP) that create the epitope precursors. If viruses were to accumulate escape mutations...
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