Nonlinear methods of vehicle velocity determination based on inverse systems and tensor products of Legendre polynomials in compact car class.

The article presents research on the methods of crash velocity determination based on the Compact car class. The database used in the research is provided by the NHTSA (National Highway Traffic Safety Administration) and includes numerous frontal crash tests, which allowed the determination of the mathematical model parameters. Two methods are presented that enable the determination of vehicle velocity before the collision. The first researched method is the so-called inversed system method and is based on the assumption that the relationship between bk coefficient Cs is an inverse function. The second line of research focuses on the tensor product method, which is grounded in the Legendre polynomials, orthogonal on the interval [-1, 1] (Axler, 1997; Cheney and Kincaid, 2002). The article presents the calculation algorithm for both cases and the results with reference to the NHTSA database (Sharma et al., 2007; Siddall and Day, 1996). The application of the least square method provides more precise results in both cases than in previously researched solutions, with a slight advantage of the tensor product method. The obtained mean relative error of the velocity determination using the inverse system method is approximately 16,22% for the linear model and 10,58% for the nonlinear model. In the case of the tensor product method the errors for linear and nonlinear models are respectively 6,74% and 6,3%.

Inactivation of Lactobacillus rhamnosus GG by fixation modifies its probiotic properties.

Probiotics are microorganisms that have beneficial effects on the host and are safe for oral intake in a suitable dose. However, there are situations in which the administration of living microorganisms poses a risk for immunocompromised host. The objective of this study was to evaluate the influence of several fixation methods on selected biological properties of Lactobacillus rhamnosus GG that are relevant to its probiotic action. Fixation of the bacterial cells with ethanol, 2-propanol, glutaraldehyde, paraformaldehyde, and heat treatment resulted in a significant decrease of alkaline phosphatase, peroxidase, and ß-galactosidase activities. Most of the fixation procedures reduced bacterial cell hydrophobicity and increased adhesion capacity. The fixation procedures resulted in a different perception of the bacterial cells by enterocytes, which was shown as changes in gene expression in enterocytes. The results show that some procedures of inactivation allow a fraction of the enzymatic activity to be maintained. The adhesion properties of the bacterial cells were enhanced, but the response of enterocytes to fixed cells was different than to live bacteria. Inactivation allows maintenance and modification of some of the properties of the bacterial cells.

Yarrowia lipolytica: the novel and promising 2-phenylethanol producer.

This is the first report on the ability of Yarrowia lipolytica strains to produce 2-phenylethanol (2-PE), which has not been identified for this species to date. 2-PE is a valuable aroma compound of rose-like odor. Its isolation from the other than microbial source-rose petals, is limited by the substrate availability. Thus, this chemical compound constitutes an attractive product for biotechnological conversions. To date, the ability to produce 2-PE has been described for such genera as Saccharomyces sp., Kluyveromyces sp., Geotrichum sp., and Pichia sp. This report provides evidence that Y. lipolytica is a novel 2-PE producer. Moreover, the titers of 2-PE obtained in Y. lipolytica NCYC3825 non-optimized cultures, nearly 2 g/l, are competitive to titers obtained by the other species.

High surface area crystalline titanium dioxide: potential and limits in electrochemical energy storage and catalysis.

Titanium dioxide is one of the most intensely studied oxides due to its interesting electrochemical and photocatalytic properties and it is widely applied, for example in photocatalysis, electrochemical energy storage, in white pigments, as support in catalysis, etc. Common synthesis methods of titanium dioxide typically require a high temperature step to crystallize the amorphous material into one of the polymorphs of titania, e.g. anatase, brookite and rutile, thus resulting in larger particles and mostly non-porous materials. Only recently, low temperature solution-based protocols gave access to crystalline titania with higher degree of control over the formed polymorph and its intra- or interparticle porosity. The present work critically reviews the formation of crystalline nanoscale titania particles via solution-based approaches without thermal treatment, with special focus on the resulting polymorphs, crystal morphology, surface area, and particle dimensions. Special emphasis is given to sol-gel processes via glycolated precursor molecules as well as the miniemulsion technique. The functional properties of these materials and the differences to chemically identical, non-porous materials are illustrated using heterogeneous catalysis and electrochemical energy storage (battery materials) as example.

Conditioned responses of monkey locus coeruleus neurons anticipate acquisition of discriminative behavior in a vigilance task.

Impulse activity was recorded extracellularly from noradrenergic neurons in the nucleus locus coeruleus of three cynomolgus monkeys performing a visual discrimination (vigilance) task. For juice reward, the subjects were required to release a lever rapidly in response to an improbable target stimulus (20% of trials) that was randomly intermixed with non-target stimuli presented on a video display. All locus coeruleus neurons examined were phasically and selectively activated by target stimuli in this task. Other task events elicited no consistent response from these neurons (juice reward, lever release, fix spot stimuli, non-target stimuli). With reversal of the task contingency, locus coeruleus neurons ceased responding to the former target stimuli, and began responding instead to the new target (old non-target) stimuli. In addition, the latency of locus coeruleus response to target stimuli increased after reversal (by about 140 ms) in parallel with a similar increase in the latency of the behavioral response. These results indicate that the conditioned locus coeruleus responses reflect stimulus meaning and cognitive processing, and are not driven by physical sensors attributes. Notably, the reversal in locus coeruleus response to stimuli after task reversal occurred rapidly, hundreds of trials before reversal was expressed in behavioral responses. These findings indicate that conditioned responses of locus coeruleus neurons are plastic and easily altered by changes in stimulus meaning, and that the locus coeruleus may play an active role in learning the significance of behaviorally important stimuli.

Locus coeruleus neurons in monkey are selectively activated by attended cues in a vigilance task.

Impulse activity was recorded extracellularly from noradrenergic neurons in the nucleus locus coeruleus (LC; 47 single-cell and 126 multicell recordings) of four cynomolgus monkeys performing an oddball visual discrimination task. For juice reward, the subjects were required to release a lever rapidly in response to an infrequent (10-20% of trials) target cue (CS+) that was randomly intermixed with nontarget (CS-) stimuli presented on a video display. All LC neurons examined were phasically and selectively activated by target cues in this task. Other task events elicited no consistent response from these neurons (juice reward, lever release, fix-spot stimuli, nontarget stimuli). In one animal, nontarget cues phasically inhibited LC neurons. Phasic LC excitatory responses to target cues in this task occurred at a relatively short latency (mean = 90.7 msec), approximately 200 msec prior to the behavioral response (lever release). In addition, LC response magnitudes varied with behavioral performance, being substantially attenuated during epochs of poor performance (high false alarm rate). There was a positive correlation (r = 0.30, p < 0.0001) between the latency of LC responses and the latency of behavioral responses to same target cues, consistent with the possibility that LC responses may have a role in selective attention by facilitating responses to the CS+ stimulus. Analyses of behavioral response latencies to pairs of stimuli indicated that LC responses may facilitate behavioral responses to subsequent sensory cues, consistent with a role of this system in sustained attention/vigilance. Moreover, responses became reduced in magnitude over time during prolonged task performance (> 90 min), in parallel with a behavioral performance decrement. These results show that LC neurons are activated selectively by attended stimuli that demand a rapid response in this task, and that such LC responses may contribute to conditioned behavioral responses.

Locus coeruleus activity in monkey: phasic and tonic changes are associated with altered vigilance.

Impulse activity of individual neurons in the nucleus locus coeruleus (LC) was recorded from chair-restrained, unanesthetized cynomolgus monkeys. LC activity was closely related to the behavioral state of the animal. In alert waking, LC neurons displayed continuous, moderately irregular activity. In contrast, prolonged pauses in activity accompanied drowsiness. These pauses preceded eye closure and occurred 1-3 s before the onset of slow-wave EEG. At awakening, LC activation preceded by up to 3 s desynchronized EEG and eye opening. LC activity during alertness varied tonically. During behavioral agitation LC activity was higher than during goal-directed task behavior (described below). In addition to these changes in tonic activity, LC neurons were also phasically responsive to certain sensory stimuli. These cells responded selectively to unexpected, meaningful sounds. LC neurons were also recorded during a visual oddball discrimination task in which the monkey was required to selectively release a lever in response to an infrequent visual cue (target cue; CS+) to receive juice reward. LC neurons were selectively activated by CS+ cues in this task; no other task events evoked LC activity. The mean latency of CS+ response was 108 ms (90 ms for multicell recordings), more than 150 ms prior to the behavioral response (lever release). These responses became smaller in later epochs during the session, along with deteriorating task performance. It is proposed that these short-lasting stimulus-evoked LC responses may help optimize behavioral responses and increase vigilance to subsequent sensory stimuli. Together, LC may contribute both to maintaining tonic levels of vigilance and to phasically modulating the current vigilance level in a stimulus-dependent mode.

DSP-4 lesion of locus coeruleus does not affect spontaneous predatory behaviour in cats.

The effect of the destruction of locus coeruleus noradrenergic (LC NA) projection on spontaneous predatory attack, predatory competition and food intake was studied in cats. Selective noradrenergic neurotoxin DSP-4 injected into LC caused 71% decrease of noradrenaline content in amygdala and 41% decrease in hypothalamus. Predatory behaviour, predatory competition as well as food intake remained unchanged. It is concluded that LC NA projection is specifically involved neither in predation nor in food intake, which is in agreement with recent electrophysiological data.

Acute morphine induces oscillatory discharge of noradrenergic locus coeruleus neurons in the waking monkey.

Neurons were recorded extracellularly from the locus coeruleus (LC) of a waking, chair-restrained cynomolgus monkey before and for 0.5-4 h after intramuscular injections of morphine sulfate (0.3-10 mg/kg). Tonic discharge of each LC neuron tested (n = 11) decreased after morphine injection; this effect appeared to be dose-dependent for the range of 0.3-3.0 mg/kg. Unexpectedly, these same doses of morphine also induced a pronounced burst-pause discharge pattern in all LC neurons recorded. Thus, whereas in the naive animal pauses in discharge longer than 3 s were rare during waking, after morphine injection LC neurons frequently exhibited pauses in impulse activity of 10 s or longer during non-drowsy waking. The bursts in activity following morphine corresponded to orienting behaviors or apparent alertness, whereas pauses were associated with eye closure or slowly drifting gaze. Closer analysis revealed that this burst-pause activity pattern was somewhat regular, with a period of about 15-35 s. This observation was confirmed by autocorrelogram analysis. In view of previous findings in rodent LC, we suggest that acute morphine elicits a dual effect on primate LC neurons: inhibition of discharge by direct effects on opiate receptors located on LC cells, and periodic phasic activation mediated by excitatory afferents to the LC.

Scopolamine-induced alterations in predatory behaviour pattern in cats.

Predatory behaviour in its full pattern (i.e., following the mouse, killing it and consuming the carcass) was tested in semi-natural conditions in cats. Consumption of minced horse meat was tested as well. Centrally acting scopolamine hydrobromide injected i.p. did not suppress predatory motivation, since following the prey and killing it were preserved. The executory phase of predation (i.e., the killing grip) was severely disturbed and the consumption of the mouse as well as meat was totally inhibited. Peripherally acting scopolamine methylnitrate administered into another group of cats under the same conditions generally did not affect predatory pattern, though meat and mouse consumption was disturbed to some extent. It is concluded that central muscarinic involvement in predatory behaviour in cats is limited to sensorimotor control of jaw movements.

The effect of imipramine on predatory behavior and locomotor activity in cats.

The behavior toward mouse was studied under and after chronic imipramine treatment in two groups of cats - non-killers and killers. Imiprarnine facilitated predatory behavior in the non-killers but not in the killers, which is in contrast to results obtained on rats. Imipramine produced a marked decrease of locomotor activity of non-killers tested in open field. The inhibition of locomotion did not interfere with the occurrence of killing behavior. It was concluded that imipramine selectively facilitates the neurophysiological mechanism of predatory behavior, which in cats might be connected with the reward system.