Ka For Activation Research Articles

Human communities living in the central Campania Plain during eruptions of Vesuvius and Campi Flegrei

Archaeological and volcanological studies have revealed that eruptions of Neapolitan volcanoes have conditioned human settlement patterns since prehistoric times. The occurrence of high intensity explosive eruptions, interspersed with long periods of quiescence, has characterized the last 10 ka of activity of these volcanoes. Geoarchaeological studies, carried out in advance of investigations for the construction of the Rome-Naples and the new Naples-Bari railway lines, have made possible a detailed reconstruction of human presence in the central part of the Campania Plain up to the coastal strip, between the late Neolithic and the late Bronze Age. The examined chronological interval includes sequences of pyroclastic deposits erupted by both Campi Flegrei and Somma-Vesuvius, and paleosols with evidence of anthropic frequentation. Altogether, the geoarchaeological data have provided a detailed picture of human settlement and activities through time with a particular focus on a long period of quiescence of the two volcanoes and also during their intense activity.

Establishing the effect of a simultaneous reduction in the filling load inside a chamber and in the content of the crushed material on the energy intensity of self-oscillatory grinding in a tumbling mill

The effect of a simultaneous change in the degree of filling a chamber with load κbr and in the content of the crushed material κmbgr on the efficiency of the self-oscillatory grinding process has been estimated.
 Using a method of numerical modeling based on the results of experimental visualization of the flow has helped establish an emergent dynamic effect of the sharp increase in the self-oscillatory action of two-faction loading at a joint reduction in κbr and κmbgr. A significant decrease in the passive quasi-solid loading motion zone has been detected, as well as an increase in the active pulsation zone and a growth of dilatancy. The manifestation of the effect is enhanced by the simultaneous interaction of increasing the scope of self-oscillations and weakening the coherent properties of particles in a loose large fraction under the influence of the particles of fine fraction. A significant decrease in the values of the inertial loading parameters has been established: maximum dilatancy υmax, the relative scale of self-oscillations ψRυ, the maximum share of the active part of κfammax, and the generalized complex degree of dynamic activation Ka. A 2.65-time growth of υmax was detected, ψRυ increased by 5 times, κfammax ‒ by 4.36 times, Ka ‒ by 18.4 times, at a joint decrease in κbr from 0.45 to 0.25, in κmbgr ‒ from 1 to 0.
 The synergistic technological effect of a sharp decrease in the specific energy intensity Еo/Еs has been established, as well as an increase in the relative performance Co/Cs in the self-oscillatory grinding, due to a significant increase in the dynamic action of loading, which is exacerbated by the joint interaction of reduced κbr and κmbgr.
 The process of the self-oscillatory grinding of cement clinker has been investigated. A 62 % reduction in Еo/Еs and a 125 % increase in Co/Cs were detected at a joint decrease in κbr from 0.45 to 0.25, in κmbgr ‒ from 1 to 0.125.
 The established effects make it possible to substantiate the parameters for the energy-efficient self-oscillatory process of grinding in tumbling mills with a conventional structure

A large refined catalog of earthquake relocations and focal mechanisms for the Island of Hawai'i and its seismotectonic implications

AbstractWe present high‐quality focal mechanisms based on a refined earthquake location catalog for the Island of Hawai'i, focusing on Mauna Loa and Kīlauea volcanoes. The relocation catalog is based on first‐arrival times and waveform data of both compressional and shear waves for about 180,000 events on and near the Island of Hawai'i between 1986 and 2009 recorded by the seismic stations at the Hawaiian Volcano Observatory. We relocate all the earthquakes by applying ray tracing through an existing three‐dimensional velocity model, similar event cluster analysis, and a differential‐time relocation method. The resulting location catalog represents an expansion of previous relocation studies, covering a longer time period and consisting of more events with well‐constrained absolute locations. The focal mechanisms are obtained based on the compressional‐wave first‐motion polarities and compressional‐to‐shear wave amplitude ratios by applying the HASH program to the waveform cross correlation relocated earthquakes. Overall, the good‐quality (defined by the HASH parameters) focal solutions are dominated by normal faulting in our study area, especially in the active Ka'ōiki and Hīlea seismic zones. Kīlauea caldera is characterized by a mixture of approximately equal numbers of normal, strike‐slip, and reverse faults, whereas its south flank has slightly fewer strike‐slip events. Our relocation and focal mechanism results will be useful for mapping the seismic stress and strain fields and for understanding the seismic‐volcanic‐tectonic relationships within the magmatic systems.

Chapter 12 Eruptive frequency and volcanic hazards zonation in São Miguel Island, Azores

Abstract São Miguel Island comprises five active volcanic systems, including three central volcanoes with calderas and two basaltic fissure systems. Volcanic eruptions in São Miguel are of basaltic and trachytic nature ( s.l. ), including Hawaiian, Strombolian, sub-Plinian, Plinian and Vulcanian events, the more explosive ones frequently including hydromagmatic phases. Large Plinian eruptions are related to caldera-forming events that occurred in the past. With reference to the Fogo A stratigraphic marker, a total of 73 individual volcanic eruptions have been identified in the last 5 ka, giving a recurrence interval of 68.5 years. Taking into account that only six events have occurred in historical times, the recurrence interval increases to 95 years and, clearly, a future event is overdue because the most recent eruption occurred in 1652. It should be noted, however, that some volcanic eruptions in the past have occurred in clusters. The eruptive frequencies of the last 5 ka of activity have been determined for all types of eruptions and related hazards, including lava flows, pyroclastic falls, pyroclastic density currents (PDCs) and lahars. The areas susceptible to volcanic products have been mapped and modelled under different eruptive conditions.

The Acute Effects of Static Stretching on Human Hopping Performance

Static stretching is related to increases in joint range of motion (ROM), however, the relationship between stretching and movement performance is unclear. Some suggest an acute bout of stretching enhances neuromuscular performance, whereas other evidence points to a detrimental effect. PURPOSE: To determine the acute effects of static stretching on performance measurements of a bouncing gait represented by bipedal hopping. METHODS: Participants were randomly assigned to either a control (C) or static stretching (EXP) group (n=12 each group). Plantar-flexor muscle activity, active ankle joint stiffness (kA), and leg stiffness (kL) were measured during preferred-height hopping. These variables were calculated for the lowering phase of ground contact, from initial contact to the lowest vertical position of the center of mass (COM). Muscle activity was measured with surface electromyographic (EMG) electrodes over the gastrocnemius (lateral and medial) and soleus muscles. Active kA was calculated as the ratio of net muscle torque to ankle angular displacement and kL was calculated as the ratio of change in vertical GRF to vertical displacement of the COM. Hopping frequency was maintained at 2.2 Hz with the aid of a metronome. In addition, measurements of active ankle dorsiflexion ROM were recorded before each trial of hopping. Participants performed two trials of 60-s hopping. Between trials the EXP group participated in static stretching of the plantar-flexor muscles and C group rested. Comparison of the change in hopping variables from one trial to the next was made between groups using a one-way MANO VA and comparison of change in active ROM between groups was made with a one-way ANOVA. RESULTS: Univariate examination of changes in active dorsiflexion ROM between the C and EXP groups demonstrated a difference (AROM: 0.0(1.1) vs. 1.6(2.0) degrees, p=0.02). Multivariate examination of the changes in hopping variables from one trial to the next showed no difference between groups (muscle activity ratio: 0.9(0.2) vs. 1.0(0.2) IEMG post/pre, δkA: 8(50) vs. 20(32) Nm rad−1, δkL 0.3(1.9) vs. 0.1(1.2) kN m−1, p=0.46). All data are presented as mean (SD), C and EXP respectively. CONCLUSIONS: The observed increase in ankle dorsiflexion ROM after static stretching is in agreement with previous findings. There is, however, no support for either an enhancing or detrimental effect of static stretching on performance measures during bipedal hopping.

CFTR activation: additive effects of stimulatory and inhibitory phosphorylation sites in the R domain.

To investigate the functional significance of individual consensus phosphorylation sites within the R domain of cystic fibrosis transmembrane conductance regulator (CFTR), serines were eliminated by substituting them with alanine. Included in this analysis were serine-660, -670, -686, -700, -712, -737, -768, -795, and -813, which lie within protein kinase A consensus sequences, and serine-641, which does not. Elimination of single potential phosphorylation sites altered the sensitivity of CFTR (expressed in Xenopus oocytes) to activating conditions in a manner that was highly site dependent. Substitution at serine-660, -670, -700, -795, or -813 significantly increased the half-maximal activation constant (KA) for activation by 3-isobutyl-1-methylxanthine, which is consistent with the hypothesis that phosphorylation at any of these sites promotes CFTR activation. The effect of substitution at serine-813 was significantly greater than at the other sites. In contrast, alanine substitution at serine-737 or -768 actually decreased the KA for activation, suggesting that phosphorylation at either of these sites is inhibitory. Substitution at serine-641, -686, and -712 had no significant effect on activation sensitivity. The effects of multiple serine to alanine substitutions were consistent with the notion that phosphorylation at individual sites produced roughly additive effects, suggesting that the effect produced by phosphorylation of any one serine was not dependent on the phosphorylation state of other serines. These results are consistent with the notion that, although none of the phosphorylation sites studied here are absolutely necessary for activation of CFTR, individual sites contribute differently to the gating of the channel.

Equations for calculating the constants of enzyme inhibition/activation by n inhibitors/activators

Based on the method of vector representation of enzyme reactions in three-dimensional K'mV' coordinates, equations for calculating the constants of enzyme inhibition Ki(n) and activation Ka(n) by two or more inhibitors/activators were deduced. Inhibition of calf alkaline phosphatase by anions of molybdic (MoO42-) and tungstic (WO42-) acid was studied. The constants of enzyme inhibition by each of these anions and by their mixture in the same concentration were determined. The value of the phosphatase inhibition constant obtained experimentally was compared with that calculated using the appropriate equation. The prospects of using the equations obtained to analyze the kinetics of enzyme inhibition/activation by two or more simultaneous inhibitors/activators and to assess the contribution of each of these compounds are discussed.

On linear concentration dependences of K'm, V' and 1/νi enzyme kinetic parameters

The most frequently occurring incorrect uses of the plots of intercepts, slopes and other coordinates for the determination of constants of enzyme activation Ka and of nontrivial inhibition K(IIi), K(Vi), K(Ii), were analyzed. The correct plots are shown. Calculations of the K(Ii) and K(IIi) constants of nontrivial types of enzyme inhibition using the corrected plots of the intercepts are given.

Persistence of elevated levels of galactosyl-alpha(1-3)galactose antibodies in sera from patients cured of visceral leishmaniasis

Using rabbit erythrocyte-derived neutral glycosphingolipids enriched for a ceramide pentasaccharide as the antigen, we detected elevated anti-galactosyl-alpha(1-3)galactose (anti-G alpha G) antibody levels in 76% of children with active visceral leishmaniasis (kala-azar [KA]) and in 42% of clinically cured patients with KA who had been treated about 5 years previously with meglumine antimonate (30 mg/kg in a series of 15 daily injections). The long-term persistence of elevated G alpha G antibodies was also found in 56% of children living in the same geographic zone who, at the time of the initial clinical examination, had fever and evident splenomegaly with hyperglobulinemia but a negative bone marrow aspirate for leishmanial bodies. Five years after antimonate treatment, these clinically cured children with presumptive KA were studied serologically. Their mean G alpha G antibody values were slightly lower than those in patients with active KA but were still abnormal. Using different biochemical and immunological approaches, we found that elevated G alpha G antibodies present in patients with KA bound specifically to glycoconjugates with an alpha(1-3)-terminal galactose residue. G alpha G antibodies were mainly distributed between immunoglobulin classes G and M in patients with active KA and in antimonate-treated patients with clinically cured KA. The possibility of the existence of remnant living parasites or the persistence of inserted G alpha G epitopes in parasitized macrophages was proposed as a mechanism to explain the long-term persistence of abnormal G alpha G antibodies in patients apparently cured of KA.

Protein kinase C from small intestine epithelial cells

Protein kinase C activity has been identified in cytosolic and membrane fractions from rat and rabbit small intestine epithelial cells. The cytosolic fraction comprised about the 75% of total activity. Protein kinase C activity was resolved from other protein kinase activities by ion exchange chromatography. Phosphatidylserine or phosphatidylinositol were required for protein kinase C to be active. In addition, the activity was enhanced by the presence of a diacylglycerol. Diolein and dimyristin were the most effective (13-14 fold activation). In the presence of phosphatidylserine and diolein, the Ka for activation by Ca2+ was 10(-7)M. The phorbol ester TPA substituted for diacylglycerol in activating protein kinase C. Brush border and basolateral membranes contained protein kinase C activity, although the specific activity of the basal lateral membranes was four-fold higher than the specific activity of the brush border membranes. The presence of PKC in small intestine epithelial cells might have important implications in the Ca2+ mediated control of ionic transport in this tissue.

Protein kinase C activity in renal microvillus membranes

Protein kinase C activity was found in rabbit renal microvillus membrane vesicles. C-kinase activity was assayed by examining H 1 histone phosphorylation using microvillus membrane vesicles dispersed with Triton X. Calcium-activated protein kinase activity was only demonstrable in the presence of phosphatidylserine (PS). With PS (15 μg/ml) the Ka for activation by calcium was 1.04 μM. This was reduced to 0.38 μM by addition of diolein (3.75 μg/ml). These activations were dose-dependent and their combined synergistic activation could be reproduced by the combination of PS (15 μg/ml) and the phorbol ester, TPA (1.17 ng/ml). During microvillus membrane purification, protein kinase C activity enriched 5-fold relative to its activity in the homogenates. The activity was not due to trapped cytosol or adventitious association with microvillus membranes during homogenization. During further purification on sucrose gradients, the C-kinase activity coenriched with brush border and not with basolateral enzyme markers. We conclude that protein kinase C is a normal component of the renal microvillus membrane.