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Because quartz veins are common in fault zones exhumed from earthquake nucleation temperatures (150°C–350°C), quartz cementation may be an important mechanism of strength recovery between earthquakes. This interpretation requires that cementation occurs within a single interseismic period. We review slip‐related processes that have been argued to allow rapid quartz precipitation in faults, including: advection of silica‐saturated fluids, coseismic pore‐fluid pressure drops, frictional heating, dissolution‐precipitation creep, precipitation of amorphous phases, and variations in fluid and mineral‐surface chemistry. We assess the rate and magnitude of quartz growth that may result from each of the examined mechanisms. We find limitations to the kinetics and mass balance of silica precipitation that emphasize two end‐member regimes. First, the mechanisms we explore, given current kinetic constraints, cannot explain mesoscale fault‐fracture vein networks developing, even incrementally, on interseismic timescales. On the other hand, some mechanisms appear capable, isolated or in combination, of cementing micrometer‐to‐millimeter thick principal slip surfaces in days to years. This does not explain extensive vein networks in fault damage zones, but allows the involvement of quartz cements in fault healing. These end‐members lead us to hypothesize that high flux scenarios, although more important for voluminous hydrothermal mineralization, may be of subsidiary importance to local, diffusive mass transport in low fluid‐flux faults when discussing the mechanical implications of quartz cements. A renewed emphasis on the controls on quartz cementation rates in fault zones will, however, be integral to developing a more complete understanding of strength recovery following earthquake rupture.Plain Language Summary: The strength of faults varies in time throughout the earthquake cycle. We know from laboratory experiments that fault strength decreases dramatically and instantaneously during earthquakes. Some, much, or all of that strength loss is recovered between earthquakes. This process, often referred to as fault “healing,” is thought to influence the timing, location, and energy of future earthquakes. The speed and mechanism of the healing process are not well known. In many fault rocks from depths of earthquake nucleation (>10 km), seen in geological exposures, slip‐related fractures and cracks are sealed with quartz cements that formed from fluids residing within, or flowing through, the fault zone. This observation has led to the common inference that quartz cementation exerts a major control on fault healing. This interpretation requires that sufficient quartz grows between successive earthquakes. We review and explore a variety of processes that have been argued to facilitate such rapid cementation. Ultimately, we find that it is difficult for quartz to grow fast enough to heal faults on the timescale of the earthquake cycle in many circumstances. Therefore, we call for more work on understanding whether quartz growth or alternative mechanisms can explain healing between earthquakes.Key Points: We critically review the potential role(s) of quartz cementation as a mechanism of fault “healing” on seismic cycle timescalesOur current understanding of silica kinetics cannot explain cementation of mesoscale fault‐fracture networks within interseismic periodsThin principal slip zones may be cemented interseismically but a complete understanding of fault‐related quartz growth requires further work [ABSTRACT FROM AUTHOR]

The seismic moments observed for low‐frequency earthquakes (LFEs) vary over multiple orders of magnitude, even where the LFEs occur within families of similar events. Although this variability is typically interpreted to record a scale‐limited process at the LFE source, neither the slip per LFE nor the rupture area can be determined from seismological constraints. Here, we examine incrementally developed slickenfibers that have been proposed to record LFEs in exhumed subduction zones. These structures form through repeated, micron‐scale slip events across dilational irregularities in the fault plane, which are punctuated by cementation and sealing in the interstitial space. By statistically analyzing the geometry of inclusion trails delineating slip‐parallel mineral‐growth increments, we constrain the variability in slip per inferred LFE and test end‐member hypotheses regarding the controls on LFE moments. We find that that the slickenfibers exhibit characteristic slip increments, favoring a "slip‐limited" model that requires large variability in LFE rupture areas. Plain Language Summary: Low‐frequency earthquakes (LFEs) are a category of seismic phenomena only perceptible by geophysical instruments. Understanding what causes these events, however, may help us understand larger magnitude earthquakes occurring along plate boundaries. Unfortunately, the physical processes that generate LFEs at their source depth are poorly understood. Seismological studies have shown that energy release varies substantially from one LFE to another, for example, but the causes of this variability are unclear. Given that energy release is proportional to the area of LFE rupture and the slip during the LFE, a common conceptual model argues that the variability in LFE energy release results from a wide variation in slip amount occurring over a relatively constant area between events. We utilize a unique record of slip events extracted from geological structures (inferred to record ancient LFEs) to test competing models governing energy release at the LFE source. Using a statistical test that quantifies the variability of slip increment recorded in rock samples, we find that the amount of slip during individual inferred LFEs has a strong preferred value with little variation between events. This result indicates variations in LFE energy release are determined primarily by variations in the area over which the slip occurs. Key Points: We examine slip increments associated with LFE structures in geological exposuresStatistical analysis shows that the slicken fibers record characteristic slip incrementsResults indicate slip‐limited seismic moments during low frequency earthquakes [ABSTRACT FROM AUTHOR]

We document the mechanical and geochemical processes of fault rock development in the shallow San Andreas fault (Mojave segment), and quantify their importance in shaping the mineralogy, grain size, fabric, and frictional characteristics of gouge. Through a combination of field and laboratory analysis of an extensive suite of shallow (<150 m) drill cores, we show that fault rocks evolved from a granodiorite protolith via three main processes: distributed microfracturing/pulverization; cataclastic flow and incipient fabric development; and production of authigenic illite/smectite during fluid-rock interaction. The interdependence of these mechanical and geochemical processes results in a diverse suite of fault rocks, and causes significant changes in frictional strength. Spatial variations in the effects of these mechanisms, as manifested in fault-rock mineralogy and geochemistry, indicate marked variations in their relative contribution to fault-rock evolution. These data reveal a complex San Andreas fault with multiple principal slip zones and damaged and altered rock hosting numerous interconnected secondary slip surfaces. The resulting picture of the San Andreas Fault zone suggests a substantial departure from the simple structures envisioned for near-surface seismogenenic faults in numerical models is required, and may inform future efforts to forecast peak ground accelerations during southern California earthquakes. [ABSTRACT FROM AUTHOR]

We argue that the kind of political information voters should possess varies contextually in response to relevant political processes. Focusing on the partisan organization of legislatures, we derive hypotheses for what the typical American should know about politics at the national and state level and test these hypotheses in two studies. The first documents a dramatic change in American political knowledge at the national level in response to polarization—the replacement of individually oriented information with partisan information. While voters' ability to identify the candidates running to represent them in Congress has been cut in half, their ability to rank order the parties ideologically has nearly doubled. The second study provides evidence that voters are better able to identify the majority party in their state legislature where partisan control of the legislative agenda and roll‐call voting is stronger. We conclude by discussing the implications of our findings. [ABSTRACT FROM AUTHOR]

Fracture cementation is an important control on the recovery of prefailure levels of permeability and strength in faults. The timescales of this process, however, are almost entirely unknown from direct analysis of the rock record. We report U‐Th dating results that quantify rates of fracture cementation in syntectonic calcite veins from the Loma Blanca fault, New Mexico, USA. Measured rates vary from ~0.05 to 0.80 mm/ka and exhibit a power function correlation with minimum fracture apertures. We argue that this correlation is the result of crystal growth in a transport‐limited system, where cementation rates were proportional to rates of postseismic fluid flow in individual fractures. We further argue that such transport‐limited, flux‐dependent cementation necessarily leads to a heterogeneous distribution of permeability and strength recovery as fluids migrate through fault‐zone fracture networks. These heterogeneities may influence rupture propagations pathways and the continual development of fault‐zone architecture/complexity. Plain Language Summary: Fractures formed during earthquakes greatly increase the permeability of fault zones while decreasing their strength, thereby exerting a significant influence on the cycle of earthquakes in the crust. Permeability and strength, however, experience partial recovery during interseismic times, a process referred to as fault or fracture "healing." Precipitation of minerals within fractures is commonly cited as an important control on healing, but rates of this process are largely unknown. We present the results of a novel sampling approach which allowed us to estimate the rates of fracture cementation in a seismogenic fault in New Mexico, USA. Our results show that cementation rates are highly variable among individual fractures. Rates of fracture cementation are strongly correlated with the aperture (or width) of the original fracture during healing. We conclude that cementation rates that are dependent on rates of fluid flow through individual fractures following earthquakes, with the widest fractures accommodating more fluid flow and rapid healing. This suggests healing of faults during interseismic periods is spatially heterogeneous and continuously migrates as fracture networks evolve. Key Points: U‐Th dating was used to estimate the timescales of calcite cementation and healing/sealing in fault‐localized fracturesResults suggest that cementation rates are "flux dependent" and proportional to rates of postseismic fluid flow through fracturesThis dependency likely leads to heterogeneous distributions of postseismic recovery of permeability and strength in fault damage zones [ABSTRACT FROM AUTHOR]

We analyzed a catalog of 31 published earthquake chronologies to assess the commonality of quasiperiodic earthquake recurrence across a range of fault types and tectonic settings. The statistical approach we employ differs from previous methods in that it explicitly incorporates numeric uncertainties in the earthquake chronologies while recognizing that random sequences of events (against which the chronologies are tested) may appear to be less disordered over the short time scales typical of most published records. Our results show that 58% of the chronologies support an interpretation of quasiperiodic recurrence (probability of random recurrence < 10%). These include strike‐slip, normal, and reverse faults in both plate‐boundary and intraplate environments, which exhibit evidence for quasiperiodic recurrence with comparable frequency. We conclude that quasiperiodic failure is likely the norm for faults in the seismogenic crust and that stress renewal is a first‐order control on fault rupture across a wide range of tectonic settings. Plain Language Summary: Do large earthquakes occur at regular intervals through time? For over 100 years, this question has been at the center of efforts to determine earthquake hazards in seismically active regions that are home to millions of people around the world. Answering it requires extended observation of recurrent earthquakes on individual faults. These faults, however, produce relatively few large earthquakes over human time scales. Geologists have solved this problem by using radiometric dating to determine the age of "fossil" earthquakes recorded in the geologic record, leading to records containing as many as 30 events recorded over tens or hundreds of thousands of years. Few of these records, however, have been tested statistically to determine whether they record periodic (versus random) earthquake recurrence. Here we employ a statistical analysis which answers a simple question, "what is the probability that a given series of earthquakes was produced by random behavior?" By applying this analysis to a catalog of 31 previously published large‐earthquake records, we find that the majority (58%) of the cases have less than a 10% chance of having been produced through random action. Our results suggest that quasiperiodic earthquake recurrence is likely normal behavior for seismogenic faults in the Earth's crust. Key Points: We statistically assess the commonality of quasiperiodic earthquake recurrence in 31 previously published large‐earthquake chronologiesMost of the chronologies support an interpretation of quasiperiodic recurrence (probability of random recurrence < 10%)Results suggest that stress renewal is a first‐order control on fault rupture across a wide range of tectonic settings [ABSTRACT FROM AUTHOR]

CD4 counts and viral loads are dynamic quantities that change with time in HIV-infected persons. Commonly used single summary measures, such as viral load set point or early CD4 count, do not explicitly account for changes in viral load or CD4 counts or other features of the overall time course of these measures. However, the efficient use of all repeated measurements within each subject is often a challenge made more difficult by sparse and irregular sampling over time. Here, we illustrate how functional principal component (FPC) analysis provides an effective statistical approach for exploiting the patterns in CD4 count and viral load data over time. We demonstrate the method by using data from Kenyan women who acquired HIV-1 during follow-up in a cohort that practices high-risk activities and were subsequently followed up prospectively from early infection. The FPC scores for each woman obtained using this method served as informative summary statistics for the CD4 count and viral load trajectories. Similar to baseline CD4 count or viral set point, the first FPC score can be interpreted as a single-value summary measure of an individual's overall CD4 count or viral load. However, unlike most single-value summaries of CD4 count or viral load trajectories, the first FPC score summarizes the dynamics of these quantities and is seen to reveal specific features of the trajectories associated with mortality in this cohort. Moreover, the FPC scores are shown to be a more powerful prognostic factor than other common summaries when used in survival analysis. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The article talks about the product design process at Johnson & Johnson. The Design for the Environment (DfE) process at Johnson & Johnson (J&J) allows product development teams to identify and address potential environment-related issues in the early development process, without removing the company's maximum flexibility to make changes. DfE at Johnson & Johnson has three main motivations, which include maximizing efficiency and minimizing impact throughout the product's life cycle. More information is given in the article.

Examines whether changes in the aggregate policy preferences of voters in United States democracies relate symmetrically to national economic performance. Effect of change in economy size on direction of aggregate policy preference; Change in policy mood; Analogy between consumer choice and the individual's demand for different public policies; Measurement of aggregate policy preferences across countries and overtime.

Applies an empirical framework that is appropriate for modeling coalition choice to evaluate several leading explanations of government formations. Role of approach in making conclusions about the relative importance of traditional variables relating to size and ideology; Assessment of the impact of contemporary institutionalist theories on the ability to explain and predict government formation.

The concentration of certain metabolic intermediates in the spadix of Arum has been determined over the complete period of floral development from the point at which the spathes are first visible in the leaf base to thermogenesis in the spadix. These intermediates include sucrose, glucose, fructose, pyruvate, alanine, citrate, α-ketoglutarate, glutamate, glutamine, malate, aspartate and asparagine. Assays for these intermediates were supplemented by measurements of mitochondrial respiratory activity, soluble and protein-bound flavins, thiamine and ethanol-insoluble materials. These constituents and processes reveal four broad patterns of change indicating a complex system controlling floral development and thermogenesis. The clearest indication of a specific control seen is the correlation of low mitochondrial respiratory activity with low levels of soluble flavins, suggesting that lack of these cofactors limits the respiratory activity of young spadices. [ABSTRACT FROM AUTHOR]

Eight enzymes concerned with carbohydrate metabolism, extracted and partially purified from mycorrhizal roots of beech, were studied to determine the possible role of a number of sugar alcohols (polyols) as effectors for the carbohydrate metabolism of the roots. Various patterns of inhibition of these enzymes by different polyols were found, Mannitol and threitol were the most effective of the polyols studied in terms of the number of enzymes affected and the apparent inhibition constants for the affected reactions. None produced an activation of the enzyme reactions. The possible significance of these enzyme inhibitions as indicating ways in which the presence of the sheath of fungal mycelium may alter the utilization of carbohydrate in the tree and result in translocation to the symbiotic fungus, and the relation of these findings to the known characteristics of mycorrhizas are discussed, [ABSTRACT FROM AUTHOR]

Malate oxidation by mitochondria prepared from stage γ Arum spadices is inhibited by ADP. When oxaloacetate is also present, the effect of ADP is to increase the rate of oxygen uptake to one well in excess of the rate with malate alone. Arum mitochondria cannot oxidize oxaloacetate alone, but when increments of ADP or other nucleotides are added with oxaloacetate, oxygen uptake begins and continues for an extended period at a constant rate. The rate is proportional to the amount of nucleotide added. The stimulation of oxaloacetate oxidation by nucleotides increases in the order AMP

Over a flowering season of 7 weeks, mitochondria from the spadices of Arum maculatum showed a progressive increase in the rate at which added malate was oxidized from less than 20 nmoles mic[sup-1] mg protein[sup-1] to more than 700 nmoles min[sup-1] mg protein[sup-1]. In the oxidation of succinate, α-ketoglutarate and other substrates, much smaller differences in rate were found. Mitochondria oxidizing malate responded to the addition of high (3.8 mM) concentrations of cyanide by stimulation when their initial rate of malate oxidation was low and by inhibition when it was high. Stimulation by KCN even with high concentrations did not increase the O[sub2] uptake rate of young spadices to the level of mature ones. Associated with this alteration in response to cyanide was a reverse response to ADP. The early, slowly respiring mitochondria which were stimulated by KCN were often inhibited by ADP while the mitochondria from later spadices which were inhibited by KCN were usually stimulated by ADP. Similar variations in the relative rate of malate oxidation, response to cyanide and to ADP were observed in mitochondria prepared on the same day from spadices at different stages of development from the same location. In this case the change from young (β) to fully matured (∊) spadices approximately paralleled those from the early season to the end of the flowering period. The changes in malate metabolism of the spadix mitochondria were not solely related to stage of spadix development, however, since those from spadices at the same apparent developmental stage gathered over a 5-week period also showed an increase in the rate of malate oxidation and a change in response to cyanide and ADP. [ABSTRACT FROM AUTHOR]

Phosphoenolpyruvate carboxylase (PEPC) from higher plants is usually assayed by using malate dehydrogenase (MDH) as a coupling enzyme. To avoid erroneous readings caused by metal ions, which convert oxaloacetate (OAA) to pyruvate, lactic dehydrogenase can be included. Reporting the total NADH used by both coupling enzymes gives the total OAA production. Microbial PEPC has been assayed by employing citrate synthase (CS) as a coupling enzyme which detects the reaction of CoA with Ellman's reagent. Comparable Km values for MgPEP are found with the two assays. When MDH alone is used as the coupling system, the Vmax value is about 60% larger than the one found with the CS assay. However, when MDH is added to the CS assay without the NADH cofactor, Vmax is brought back to the same level as that with the NADH-coupled enzyme. Malate inhibition of PEPC assayed with the CS coupling system is blocked by low concentrations of citrate in the range produced in the assay. High concentrations of citrate inhibit PEPC. Glucose-6-phosphate in concentrations higher than 1 mM blocks the response of PEPC to added MDH in the CS assay. [ABSTRACT FROM AUTHOR]

Malate dehydrogenase isoenzymes from the blades of different leaves of the cotton plant have been investigated. The total extractable malate dehydrogenase activity varied widely between leaves of different ages and different locations on the plant. Malate dehydrogenase zymograms developed from the extracts which contained significantly different from the enzyme activity appear to indicate the presence of different groups of malate dehydrogenase isoenzymes in leaves of different ages. However, under appropriate conditions of polyacrylamide gel electrophoresis , the same number of malate dehydrogenase isoenzymes with the same relative mobilities were detected in all the leaves studied. These findings are discussed in relation to reports that malate dehydrogenase isoenzymes change with plant development or that they have different roles in the plant. [ABSTRACT FROM AUTHOR]

Brain-derived neurotrophic factor (BDNF) influences dopamine and serotonin neurotransmission in the brain, both of which are involved in the reward system of addiction. The BDNF gene is located in a genomic region on chromosome 11p where we and others have found 'significant' linkage to nicotine dependence (ND). We tested the potential role of variants within BDNF in vulnerability to ND, which was assessed by Smoking Quantity (SQ), the Heaviness of Smoking Index (HSI), and the Fagerström Test for ND (FTND). Six single nucleotide polymorphisms (SNPs) in BDNF were analyzed in an extensively phenotyped cohort of 602 nuclear families with smokers and non-smokers of African-American (AA) or European-American (EA) ancestry. Individual SNP analysis revealed that two SNPs in the pooled male and three SNPs in the EA male samples were significantly associated with at least one adjusted ND measure. However, none of these associations remained significant after correction for multiple testing. Haplotype analysis of rs6484320-rs988748-rs2030324-rs7934165 revealed that a major T-C-T-G haplotype was significantly associated, even after Bonferroni correction, with the three ND measures in the pooled and EA male samples (maximum Z = 3.00, P = 0.002 and maximum Z = 3.13, P = 0.0009 for SQ, respectively). No significant association of a major haplotype with ND was found in the AA or EA female smokers. The significant association of BDNF variants with ND implies that this gene plays a role in the etiology of ND in EAs and that its involvement is gender specific. BDNF may warrant further investigation in ND., ((c) 2005 Wiley-Liss, Inc.)

The stabilities of subtilisin and lysozyme under hydrostatic pressures up to 200 MPa were investigated for up to 7 days at 25 degrees C. Methods were chosen to assess changes in tertiary and secondary protein structure as well as aggregation state. Tertiary structure was monitored in situ with second derivative UV spectroscopy and after pressure treatment by dynamic light scattering and second derivative UV spectroscopy. Secondary structure and potential secondary structural changes were characterized by second derivative FTIR spectroscopy. Changes in aggregation state were assessed using dynamic light scattering. Additionally, protein concentration balances were carried out to detect any loss of protein as a function of pressure. For the conditions tested, neither protein shows measurable changes in tertiary or secondary structure or signs of aggregation. Lysozyme concentration balances show no dependence on pressure. Subtilisin concentration balances at high protein concentration (4 mg/mL and higher) do not show pressure dependence. However, the concentration balances carried out at 0.4 mg/mL show a clear sign of pressure dependence. These results may be explained by protein interaction with the vial surface and appear to be rate limited by the equilibrium between active and inactive protein on the surface. Pressure increases protein loss, and the estimated partial molar volume change between the two states is estimated to be -20 +/- 10 mL/mol.

Lyophilization, or freeze-drying, of pharmaceutical proteins is often the only processing method that provides requisite long-term product stability. Freezing and drying, however, can cause acute damage to proteins. To alleviate damage, formulations frequently include protein stabilizers (often polymers and/or sugars), as well as buffering salts and "inert" bulking agents. While great efforts are placed on developing a formulation and suitable lyophilization cycle, incompatibilities among components through freezing and drying have been almost completely ignored. We demonstrate that solutions of poly(ethylene glycol) (PEG) and dextran, initially below critical concentrations for phase separation, do indeed experience a liquid-liquid phase separation induced by freeze concentration during the lyophilization cycle. The separation is shown to evolve with annealing at -7 degrees C and can be effectively inhibited simply by replacing NaCl with KCl in the formulation buffer. In addition, we show that phase separation causes unfolding of a model protein, recombinant hemoglobin, when freeze-dried in the PEG/dextran system. When the phase separation is averted by switching to KCl, the protein structural damage is also avoided. Measurements of pH in the frozen solutions show that the structural damage is not a result of pH changes. We suggest that KCl forms a glass with rapid cooling which kinetically prevents the phase separation and thus the protein structural damage.

We demonstrate that a surfactant-stabilized molten globule intermediate exists for recombinant human growth hormone (rhGH), is very hydrophobic, and tends to form aggregates. Characterization of this intermediate included equilibrium denaturation measured by electron paramagnetic resonance (EPR) and CD spectroscopy, assessment of aggregation during refolding, and fluorescence studies of its binding to the hydrophobic probe, 1-anilinonapthalene-8-sulfonate (1,8-ANS). We have found that at 4.5 M guanidinium hydrochloride (GuHCl), a molten globule intermediate of rhGH is stabilized and results in significant aggregation upon refolding. This intermediate is populated by the addition of the nonionic surfactant, Tween. This surfactant also reduces the extent of aggregation during refolding of rhGH from 4.5 M GuHCl. Overall, our studies reveal that rhGH forms a molten globule-like intermediate during folding and this intermediate self-associates. This self-association is reduced upon formation of a Tween-rhGH complex. Tween also binds to the native protein. Thus, nonionic surfactants such as Tween may act like molecular chaperones in facilitating protein folding while not altering the native conformation.

Sub-micrometer-sized particles of poly(L-lactic acid) may be formed by using near-critical or supercritical carbon dioxide as an antisolvent to precipitate poly(L-lactic acid) from droplets of methylene chloride solution sprayed into a carbon dioxide continuous phase. Particle sizes may be controlled by varying the density of the carbon dioxide; at constant temperature in the supercritical region, higher carbon dioxide densities yield larger particles. Two methods (one batch and one continuous) for introducing the poly(L-lactic acid) solutions into carbon dioxide are demonstrated. Although the two methods use very different mechanisms for forming the droplets, similar particle sizes are observed as a function of carbon dioxide density. We suggest that mass transport, rather than jet breakup and hydrodynamics, controls particle sizes in the near-critical and supercritical regions.