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The geochemical alteration of host rocks might affect the productivity and the potential for induced seismicity of geothermal systems. In addition to natural alteration, following production and heat extraction, re‐injected fluids at lower temperatures and different pressures may be in chemical disequilibrium with the rock, impacting mineral solubility and dissolution/precipitation processes. In this study, we investigate the effect of geochemical alteration on the frictional behavior of granites, and their seismogenic potential, by conducting direct shear experiments using samples with varying degrees of alteration. The samples originate from the Carnmenellis granite in Cornwall, SW England, and represent the formation used in the United Downs Deep Geothermal Power Project for heat extraction. Experiments were conducted on granite powders (referred to as gouges) at room temperature and 180°C, at simulated in situ confining and pore pressures of 130 and 50 MPa, respectively (∼5 km depth). With increasing degree of alteration, the frictional strength of the gouges decreases while frictional stability increases. At high temperature, frictional stability is reduced for all samples while maintaining the trend with alteration stage. Microstructural investigation of the sheared gouges shows alteration delocalizes shear by reducing grain size and increasing clay fraction, which promotes the formation of pervasive shear fabrics. Our work suggests that, within the range of tested pressures, more alteration of granite initially causes more stable shearing in a fault. This behavior with alteration is sustained at high temperatures, but the overall frictional stability is reduced which increases the potential for induced seismicity at higher temperatures. Plain Language Summary: Geothermal systems are of high interest as renewable energy source. However, hot fluids in the deep subsurface can chemically react with the host rock they flow through. These reactions then affect the fluid chemistry and the rock mineral composition. With changes in mineral composition, changes in mechanical and hydraulic properties are observed. We test the effects of a specific group of reactions (argillic alteration) on the frictional properties of granite powders by using an example rock that is targeted in geothermal projects in Cornwall, SW England. The frictional properties give information about how likely it is for granitic rocks to produce an earthquake while sliding. Our tests show that the more the granite has chemically changed, the easier the powder is to slide but the more stably it will slide. This means that chemically changed powders are less likely to create seismic waves on sliding. In addition, tests at high temperature (180°C) showed the same stabilizing effect within the reacted rocks but the general sliding stability was reduced over all samples. This implies that the potential for earthquakes is higher at higher temperatures, although the analyzed chemical reactions reduce this potential in granitic geothermal systems. Key Points: Large fault systems are targeted at depth as geothermal reservoirs in high‐heat producing granites in CornwallDirect shear experiments were conducted on a series of successively more naturally altered granites from a fault in Carnmenellis graniteAlteration makes sliding more likely but also more stable, while higher temperatures destabilize shearing [ABSTRACT FROM AUTHOR]

Mature fault cores are comprised of extremely fine, low permeability, clay‐bearing gouges. Saturated granular fault materials are known to dilate in response to increases in sliding velocity, resulting in significant pore pressure drops that can suppress instability. Up to now, dilatancy has been measured predominantly in clay‐poor gouges. Clay minerals have low frictional strengths and, in previous experiments, even small proportions of clay minerals were shown to affect the frictional properties of a fault. It is important, therefore, to document in detail the impact of the proportion of clay on the frictional behavior and dilatancy of fault rocks. In this work, a suite of triaxial deformation experiments elucidated the frictional behavior of saturated, synthetic quartz‐clay (kaolinite) fault gouges at effective normal stresses of 60, 25, and 10 MPa. Upon a 10‐fold velocity increase, gouges of all clay‐quartz contents displayed measurable dilatancy with clay‐poor samples yielding comparable changes to previous studies. Peak dilation did not occur in the pure quartz gouges, but rather in gouges containing 10 to 40 wt% clay. The clay content of the simulated gouges was found to control the gouge frictional strength and the stability of slip. A transition occurred at ∼40 wt% clay from strong, unstably sliding quartz‐dominated gouges to weak but stably sliding clay‐dominated gouges. These results indicate that in a low permeability, clay‐rich fault zone, the increases in pore volume could generate pore‐fluid pressure transients, contributing to the arrest of earthquake nucleation or potentially the promotion of sustained slow slip. Plain Language Summary: The strength of faults is dependent on the fluid pressure contained within the pore space of fine‐grained fault rocks on which fault slip events such as earthquakes occur. When slip velocity increases at the start of an earthquake, the fault rocks dilate, thereby reducing the fluid pressure and consequently strengthening the fault. If this strengthening is sufficient, an earthquake may arrest. Clay minerals are commonly present within faults, but previous measurements of fault volume changes have focused on clay‐poor materials. In this study, a series of experiments simulated the conditions within a tectonic fault in the Earth's crust. The experiments focused on the effect of changing the proportion of clay on the strength, slip behavior and volume changes of the fault material. All of the experiment materials experienced measurable volume changes that would change the pressure, and therefore the strength, of the fault. Fault composition was found to control both the strength and slip behavior of the fault. Clay‐poor materials were stronger and more likely to initiate earthquake slip, whereas the clay‐rich materials were weaker and slip via steady creep. This study provides essential insight and data toward understanding the slip behavior of faults, from slow fault creep to earthquakes. Key Points: Dilatancy with increasing slip velocity is seen for fault gouges ranging from 100 wt% quartz to 100 wt% clayDilatancy is at a maximum in the quartz‐rich, clay‐poor gouges, rather than in the end member compositionsIncreasing clay content systematically decreases the gouge frictional strength and promotes velocity strengthening behavior [ABSTRACT FROM AUTHOR]

Laboratory measurements of constitutive frictional parameters are commonly inferred to explain the wide variety of slip behavior seen on natural faults. The extent to which these small‐scale measurements directly relate to fault slip behavior remains obscure. In this work, we compare laboratory‐determined frictional parameters on surface‐derived samples from along the length of the Longitudinal Valley Fault (LVF) in Taiwan with the observed slip behavior and with frictional parameters obtained geodetically. The LVF displays partially locked and creeping sections and a Mw 6.8 event in 2003 produced transient acceleration of slip in the adjacent creeping sections that can be used to determine the frictional parameters for direct comparison with the laboratory‐measured ones. We find that the laboratory‐measured friction parameters are markedly different for samples collected from the creeping and partially locked sections of the fault, the former showing lower friction coefficients and more positive values of the fault stability parameter (a−b). Moreover, values for the product of (a−b) and the effective normal stress, determined geodetically, relate very closely to those measured in the laboratory. Mineralogical and microstructural analyses of the fault gouges show that some mineralogically similar gouges produce distinctly different frictional behavior, and that this may be related to the presence and distribution of kaolinite. We conclude overall that upscaling of laboratory measurements of fault frictional properties appears to reflect well the large‐scale slip behavior of faults. Plain Language Summary: Tectonic faults contained within the Earth's crust can sometimes slip in continuous slow steady motion, known as "creep." They can also sometimes slip in a more episodic fashion, during earthquakes, and stay locked the rest of the time. Both behaviors result in different surface movement, quantifiable via geodetic methods. Models of fault slip behavior typically rely on data derived from laboratory friction measurements on rocks from fault zones. However, it is unclear whether the small‐scale laboratory measurements directly relate to observed large‐scale fault behavior. Here, we used fault rock samples from the Longitudinal Valley Fault (LVF) in Taiwan to compare the results from laboratory measurements with the slip behavior and inferred frictional properties from geodetic observations. Samples were taken both from the partially locked and creeping parts of the fault. We performed laboratory measurements on these samples that yield results that correctly predict either earthquake slip or creep. We also used the geodetic measurements of the LVF to derive the same parameters that are measured in the laboratory and find they compare well. We conclude that small‐scale laboratory measurements indeed reflect the intrinsic frictional properties of the LVF that result in the observed large‐scale behavior of this major tectonic fault. Key Points: Laboratory‐determined frictional parameters are compared with those obtained geodetically and with observed fault slip behaviorDerived friction parameters correspond well with each other and are distinctive for creeping and partially locked sections of the faultUpscaling of laboratory measurements of fault frictional properties reflects the large‐scale slip behavior of faults well [ABSTRACT FROM AUTHOR]

Tectonic pseudotachylytes are thought to be unique to certain water‐deficient seismogenic environments and their presence is considered to be rare in the geological record. Here, we present field and experimental evidence that frictional melting can occur in hydrothermal fluid‐rich faults hosted in the continental crust. Pseudotachylytes were found in the >40 km‐long Bolfín Fault Zone of the Atacama Fault System, within two ca. 1 m‐thick (ultra)cataclastic strands hosted in a damage‐zone made of chlorite‐epidote‐rich hydrothermally altered tonalite. This alteration state indicates that hydrothermal fluids were active during the fault development. Pseudotachylytes, characterized by presenting amygdales, cut and are cut by chlorite‐, epidote‐ and calcite‐bearing veins. In turn, crosscutting relationship with the hydrothermal veins indicates pseudotachylytes were formed during this period of fluid activity. Rotary shear experiments conducted on bare surfaces of hydrothermally altered rocks at seismic slip velocities (3 m s−1) resulted in the production of vesiculated pseudotachylytes both at dry and water‐pressurized conditions, with melt lubrication as the primary mechanism for fault dynamic weakening. The presented evidence challenges the common hypothesis that pseudotachylytes are limited to fluid‐deficient environments, and gives insights into the ancient seismic activity of the system. Both field observations and experimental evidence, indicate that pseudotachylytes may easily be produced in hydrothermal environments, and could be a common co‐seismic fault product. Consequently, melt lubrication could be considered one of the most efficient seismic dynamic weakening mechanisms in crystalline basement rocks of the continental crust. Key Points: The Bolfín Fault Zone shows the first pseudotachylytes described in the Atacama Fault System giving insights of past seismic activityRotary shear experiments at seismic slip velocities resulted in formation of vesiculated pseudotachylytes in all tested conditionsNatural pseudotachylytes formed in a hydrothermal fluid‐rich environment where vesiculation is related to CO2 degassing from calcite veins [ABSTRACT FROM AUTHOR]

Concepts like the 100‐year flood event can be misleading if they are not updated to reflect significant changes over time. Here, we model observed annual maximum daily streamflow using a nonstationary approach to provide the first global picture of changes in: (a) the magnitudes of the 20‐, 50‐, and 100‐year floods (i.e., flows of a given exceedance probability in each year); (b) the return periods of the 20‐, 50‐, and 100‐year floods, as assessed in 1970 (i.e., flows of a fixed magnitude); and (c) corresponding flood probabilities. Empirically, we find the 20‐/50‐year floods have mostly increased in temperate climate zones, but decreased in arid, tropical, polar, and cold zones. In contrast, 100‐year floods have mostly decreased in arid/temperate zones and exhibit mixed trends in cold zones, but results are influenced by the small number of stations with long records, and highlight the need for continued updating of hazard assessments. Plain Language Summary: Here, we provide the first global examination of recent changes in the size, frequency, and probability of extreme river floods using historical river records. Since the 1970s, the 20‐year and 50‐year extreme river floods have mostly increased in temperate zones but decreased in arid, tropical, polar, and cold zones. In contrast, the 100‐year floods have decreased in arid and temperate zones, and show mixed results in cold zones, but at a smaller sample of sites with long records. Descriptions of changes in extreme flooding depend largely on site selection, and are constrained by availability of long‐term data. Overall, our findings highlight the importance of regularly updating flood hazard assessments under nonstationarity. Key Points: We provide the first global nonstationary assessment of changes in the magnitude, return period, and probability of observed extreme floodsWe find increasing 20‐year and 50‐year floods in temperate climate zones but mostly decreases in arid, tropical, polar, and cold zonesFor the 100‐year floods, at a smaller sample of sites, we find decreases in arid and temperate zones and mixed results elsewhere [ABSTRACT FROM AUTHOR]

Fault slip is often localized in phyllosilicate‐rich fault gouges in a manner consistent with the relatively low friction coefficients measured for dry and especially wet phyllosilicates in laboratory experiments. However, the microphysics controlling these low friction coefficients remains unclear. Here, we propose a microphysical model, inspired by microstructural observations, for the prediction of the absolute value of the friction coefficient of pure dry and wet phyllosilicates. Experimentally produced phyllosilicate gouges suggest that shearing is controlled by sliding along (001) grain/platelet interfaces operating in series with removal of overlapping grain edge barriers by basal cleavage. We derive a model incorporating a subcritical crack propagation equation for the latter, constrained by subcritical crack growth data for muscovite. Model predictions for muscovite show similar trends regarding the effects of humidity and slip velocity on friction coefficient as do experiments at room temperature. The absolute value predicted for the friction coefficient is difficult to compare with experimental values, as it critically depends on atomic scale (001) sliding resistance, which is poorly constrained by available experimental data. Further discrepancies with experimental data can be explained by effects of varying grain size, grain aspect ratio, and porosity on the friction coefficient. While numerous qualitative explanations have been proposed previously for the low friction coefficient exhibited by phyllosilicates, especially in the presence of water, our study provides a new step toward a quantitative, physically based model. Key Points: We develop a cleavage‐based model for 2:1 phyllosilicate (muscovite) frictionThe model predicts realistic trends in friction coefficient with humidity and velocityAbsolute friction coefficient depends on poorly constrained atomic scale shear resistance highlighting the need for additional experiments [ABSTRACT FROM AUTHOR]

Abstract: The strength of fault zones is strongly dependent on pore fluid pressures within them. Moreover, transient changes in pore fluid pressure can lead to a variety of slip behavior from creep to unstable slip manifested as earthquakes or slow slip events. The frictional properties of low‐permeability fault gouge in nature and experiment can be affected by pore fluid pressure development through compaction within the gouge layer, even when the boundaries are drained. Here the conditions under which significant pore fluid pressures develop are analyzed analytically, numerically, and experimentally. Friction experiments on low‐permeability fault gouge at different sliding velocities show progressive weakening as slip rate is increased, indicating that faster experiments are incapable of draining the pore fluid pressure produced by compaction. Experiments are used to constrain the evolution of the permeability and pore volume needed for numerical modeling of pore fluid pressure build up. The numerical results are in good agreement with the experiments, indicating that the principal physical processes have been considered. The model is used to analyze the effect of pore fluid pressure transients on the determination of the frictional properties, illustrating that intrinsic velocity‐strengthening behavior can appear velocity weakening if pore fluid pressure is not given sufficient time to equilibrate. The results illustrate that care must be taken when measuring experimentally the frictional characteristics of low‐permeability fault gouge. The contribution of compaction‐induced pore fluid pressurization leading to weakening of natural faults is considered. Cyclic pressurization of pore fluid within fault gouge during successive earthquakes on larger faults may reset porosity and hence the capacity for compaction weakening. [ABSTRACT FROM AUTHOR]

Phyllosilicate-rich rocks which commonly occur within fault zones cause seismic velocity anisotropy. However, anisotropy is not always taken into account in seismic imaging and the extent of the anisotropy is often unknown. Laboratory measurements of the velocity anisotropy of fault zone rocks and gouge from the Carboneras fault zone in SE Spain indicate 10-15% velocity anisotropy in the gouge and 35-50% anisotropy in the mica-schist protolith. Greater differences in velocity are observed between the fast and slow directions in the mica-schist rock than between the gouge and the slow direction of the rock. This implies that the orientation of the anisotropy with respect to the fault is key in imaging the fault seismically. For example, for fault-parallel anisotropy, a significantly greater velocity contrast between fault gouge and rock will occur along the fault than across it, highlighting the importance of considering the foliation orientation in design of seismic experiments. [ABSTRACT FROM AUTHOR]

The Alpine Fault, a transpressional plate boundary between the Australian and Pacific plates, is known to rupture quasiperiodically with large magnitude earthquakes ( M w ~8). The hydraulic and elastic properties of fault zones are thought to vary over the seismic cycle, influencing the nature and style of earthquake rupture and associated processes. We present a suite of laboratory permeability and P ( V p) and S ( V s) wave velocity measurements performed on fault lithologies recovered during the first phase of the Deep Fault Drilling Project (DFDP-1), which sampled principal slip zone (PSZ) gouges, cataclasites, and fractured ultramylonites, with all recovered lithologies overprinted by abundant secondary mineralization, recording enhanced fluid-rock interaction. Core material was tested in three orthogonal directions, orientated relative to the down-core axis and, when present, foliation. Measurements were conducted with pore pressure (H2O) held at 5 MPa over an effective pressure ( Peff) range of 5-105 MPa. Permeabilities and seismic velocities decrease with proximity to the PSZ with permeabilities ranging from 10−17 to 10−21 m2 and V p and V s ranging from 4400 to 5900 m/s in the ultramylonites/cataclasites and 3900 to 4200 m/s at the PSZ. In comparison with intact country rock protoliths, the highly variable cataclastic structures and secondary phyllosilicates and carbonates have resulted in an overall reduction in permeability and seismic wave velocity, as well as a reduction in anisotropy within the fault core. These results concur with other similar studies on other mature, tectonic faults in their interseismic period. [ABSTRACT FROM AUTHOR]

The Upper Triassic Mercia Mudstone is the caprock to potential carbon capture and storage ( CCS) sites in porous and permeable Lower Triassic Sherwood Sandstone reservoirs and aquifers in the UK (primarily offshore). This study presents direct measurements of vertical ( kv) and horizontal ( kh) permeability of core samples from the Mercia Mudstone across a range of effective stress conditions to test their caprock quality and to assess how they will respond to changing effective stress conditions that may occur during CO2 injection and storage. The Mercia samples analysed were either clay-rich (muddy) siltstones or relatively clean siltstones cemented by carbonate and gypsum. Porosity is fairly uniform (between 7.4 and 10.7%). Porosity is low either due to abundant depositional illite or abundant diagenetic carbonate and gypsum cements. Permeability values are as low as 10−20 m2 (10nD), and therefore, the Mercia has high sealing capacity. These rocks have similar horizontal and vertical permeabilities with the highest kh/ kv ratio of 2.03 but an upscaled kh/ kv ratio is 39, using the arithmetic mean of kh and the harmonic mean of kv. Permeability is inversely related to the illite clay content; the most clay-rich (illite-rich) samples represent very good caprock quality; the cleaner Mercia Mudstone samples, with pore-filling carbonate and gypsum cements, represent fair to good caprock quality. Pressure sensitivity of permeability increases with increasing clay mineral content. As pore pressure increases during CO2 injection, the permeability of the most clay-rich rocks will increase more than carbonate- and gypsum-rich rocks, thus decreasing permeability heterogeneity. The best quality Mercia Mudstone caprock is probably not geochemically sensitive to CO2 injection as illite, the cause of the lowest permeability, is relatively stable in the presence of CO2-water mixtures. [ABSTRACT FROM AUTHOR]

The Revitalised Flood Hydrograph (ReFH) method is used for estimation of design flood hydrographs in the United Kingdom. This paper comments on aspects of the method, discussing its strengths and weaknesses and comparing its results with those of other methods. Design flood peaks estimated using the ReFH method and the statistical method presented in the Flood Estimation Handbook are compared at a sample of locations across Great Britain. The ReFH method gives higher flows at two-thirds of the sites; on average 16% higher for a flood return period of 100 years. Differences between the results of the two methods are greatest on catchments with significant reservoirs and lakes and catchments with high average rainfall. Recommendations for users of the ReFH method and suggestions for further research are offered, the most urgent of which is to improve the performance of the method on heavily urbanised catchments. [ABSTRACT FROM AUTHOR]

An investigation by electron backscatter diffraction on gypsum shows that this technique can be used to study the microstructures and crystallographic preferred orientation of gypsum. Presented here are the methods, verification tests and data obtained from a naturally deformed sample of gypsum-rich rock. The electron backscatter diffraction data show the sample has a strong crystallographic preferred orientation. [ABSTRACT FROM AUTHOR]

Recently, in the Northern Apennines, geophysical data have identified the Triassic Evaporites (TE, anhydrites and dolomites) as the source region of the major extensional earthquakes of the area (M ∼ 6). In order to characterize fault zone architecture and deformation processes within the TE, we have studied exhumed evaporite-bearing normal faults within the upper crust. The structure of large displacement (>100 m) normal faults is given by 1) a zoned fault core with a wider portion of fault-parallel foliated Ca-sulphates (ductile deformation), overprinted by an inner fault core (IFC) of localized brittle deformation, and 2) wide (dolostones) to absent (Ca-sulphates) damage zones of fault fracture patterns. Fault rock assemblage within the IFC is characterized by fault breccia, gouge, and cataclasites of different grain size. Most of the deformation within the IFC is localized along thin and fault parallel principal slip surfaces (PSS) made of dolomite-rich fine-grained cataclasite. SEM analyses show an evolution from Ca- to St- to gypsum-rich mineralization, due to episodic fluid flow events channeled along the fault zones during different stages of fault exhumation. The development of the observed fault geometry can be explained by a mechanical fault evolution model where initial faulting occurs along broad and ductile shear zones within the anhydrites and causes fracturing within the dolostones. Progressive deformation within the fault core leads to the development of fault parallel dolomite-rich cataclastic layers. Their reactivation coupled with transient fluid overpressures can produce embrittlement and localization of brittle deformation within the IFC. [ABSTRACT FROM AUTHOR]

The study addresses the relational reasoning of different-aged children and how addition reasoning is related to problem-solving skills within addition and to reasoning skills outside addition. Ninety-two 5- to 8-year-olds were asked to solve a series of conceptually related and unrelated addition problems, and the speed and accuracy of all self-reported strategies were used to monitor their addition performance. Children were also given a series of general relational reasoning tasks to assess their ability to solve problems based on thematic, causal and visual relations. The results revealed that, while children were able to reason about commutativity relations, recognition of relations based on additive composition was rare. Furthermore, children's ability to reason about addition concepts increased with age and problem-solving proficiency. Reasoning about addition concepts was related to performance on the thematic, causal and visual reasoning tasks for older children but not for younger children. Overall, the findings suggest that while children's early knowledge of addition relations is domain specific, as children develop in their broader reasoning abilities these developments enhance their addition reasoning. [ABSTRACT FROM AUTHOR]

An innovative technique has been used for flood estimation in a catchment study which was carried out for the Environment Agency. The River Don drains a large part of South Yorkshire. On its major tributaries (the Rivers Rather and Dearne), flow regulators and artificial washlands are used during extreme floods to delay and attenuate peak flows, allowing the peak on the Don to pass by first. The flood hydrology of the Don catchment is therefore unusual and cannot be adequately represented by conventional methods such as those in the Flood Estimation Handbook. Instead, a 1000 year series of hourly rainfall was generated using a stochastic rainfall model. This was converted to flow data using a set of probability distributed moisture rainfall-runoff models; therefore, inflows for a hydraulic model were created. This eliminated the need to make assumptions about a design flood event, leading to more robust flood estimates throughout the Don catchment. This approach could prove to be applicable to other UK or overseas studies, particularly on large or complex catchments, or in solving joint probability problems. [ABSTRACT FROM AUTHOR]

In chamber experiments, we investigated the ventilation effectiveness and thermal comfort of a task ventilation system with an air supply nozzle located underneath the front edge of a desk and directing air towards a heated mannequin or a human volunteer seated at the desk. The task ventilation system provided outside air, while another ventilation system provided additional space cooling but no outside air. Test variables included the vertical angle of air supply (−15° to 45° from horizontal), and the supply flow rate of (3.5–6.5 l/s). Using the tracer gas step-up and step-down procedures, the measured air change effectiveness (i.e., exhaust air age divided by age of air in the breathing zone) in experiments with the mannequin ranged from 1.4 to 2.7 (median, 1.8), whereas with human subjects the air change effectiveness ranged from 1.3 to 2.3 (median, 1.6). The majority of the air change effectiveness values with the human subjects were less than values with the mannequin using comparable tests. Similarly, the tests run with supply air temperature equal to the room air temperature had lower air change effectiveness values than comparable tests with the supply air temperature lower (∼5°C) than the room air temperature. The air change effectiveness values are higher than typically reported for commercially-available task ventilation or displacement ventilation systems. Based on surveys completed by the subjects, operation of the task ventilation system did not cause thermal discomfort. With a desk-edge-mounted task ventilation system it is possible to obtain an increase in the effective ventilation rate of 50%. This could lead to reduced energy use. Also, this improvement can be gained while maintaining thermal comfort for occupants. Thus occupants can be thermally comfortable and save energy at the same time. [ABSTRACT FROM AUTHOR]

We investigated the relationship between ventilation rates and individual work performance in a call center, and controlled for other factors of the indoor environment. We randomized the position of the outdoor air control dampers, and measured ventilation rate, differential (indoor minus outdoor) carbon dioxide (ΔCO2) concentration, supply air velocity, temperature, humidity, occupant density, degree of under-staffing, shift length, time of day, and time required to complete two different work performance tasks (talking with clients and post-talk wrap-up to process information).ΔCO2 concentrations ranged from 13 to 611 p.p.m. We used multivariable regression to model the association between the predictors and the responses. We found that agents performed talk tasks fastest when the ventilation rate was highest, but that the relationship between talk performance and ventilation was not strong or monotonic. We did not find a statistically significant association between wrap-up performance and ventilation rate. Agents were slower at the wrap-up task when the temperature was high (> 25.4°C). Agents were slower at wrap-up during long shifts and when the call center was under-staffed. The productivity benefits of ventilation rates that exceed common standards such as ASHRAE Standard 62 may be small (0–2%), and other factors may have a larger impact on productivity. Understaffing and long shifts should be avoided because both showed a negative impact on performance. In this study, high temperature had the largest statistically significant impact on productivity and was caused by occupants fighting over the thermostat setpoint. Care should be taken to avoid high temperatures in call centers. If occupants are allowed to adjust temperature setpoints, then the size and/or duration of the setpoint change should be restricted. [ABSTRACT FROM AUTHOR]

Student attendance in American public schools is a critical factor in securing limited operational funding. Student and teacher attendance influence academic performance. Limited data exist on indoor air and environmental quality (IEQ) in schools, and how IEQ affects attendance, health, or performance. This study explored the association of student absence with measures of indoor minus outdoor carbon dioxide concentration (dCO2). Absence and dCO2 data were collected from 409 traditional and 25 portable classrooms from 22 schools located in six school districts in the states of Washington and Idaho. Study classrooms had individual heating, ventilation, and air conditioning (HVAC) systems, except two classrooms without mechanical ventilation. Classroom attributes, student attendance and school-level ethnicity, gender, and socioeconomic status (SES) were included in multivariate modeling. Forty-five percent of classrooms studied had short-term indoor CO2 concentrations above 1000 p.p.m. A 1000 p.p.m. increase in dCO2 was associated ( P < 0.05) with a 0.5–0.9% decrease in annual average daily attendance (ADA), corresponding to a relative 10–20% increase in student absence. Annual ADA was 2% higher ( P < 0.0001) in traditional than in portable classrooms. This study provides motivation for larger school studies to investigate associations of student attendance, and occupant health and student performance, with longer term indoor minus outdoor CO2 concentrations and more accurately measured ventilation rates. If our findings are confirmed, improving classroom ventilation should be considered a practical means of reducing student absence. Adequate or enhanced ventilation may be achieved, for example, with educational training programs for teachers and facilities staff on ventilation system operation and maintenance. Also, technological interventions such as improved automated control systems could provide continuous ventilation during occupied times, regardless of occupant thermal comfort demands. [ABSTRACT FROM AUTHOR]

Presents a study which predicted the reductions in the indoor mass concentrations of particles attainable from use of filters in building supply airstreams and from use of stand-alone fan-filter units. Methods; Results and discussion.

Energy dispersive X-ray microanalysis was used to localize the two brominated natural products (aerothinonin and homoaerothionin) in the tissues of a marine demosponge, Aplysina fistularis. Virtually all of these compounds were localized within the spherules of the spherulous cells in the mesohyl. This is the first localization of any secondary metabolite at the cellular or sub-cellular level in any marine invertebrate. In Aplysina fistularis, as in other species of the same genus studied by Vacelet, the spherulous cells are concentrated just beneath the exopinacoderm and just beneath the endopinacoderm of the excurrent canals. Moreover, there is electron microscopic evidence for degeneration of some spherulous cells throughout the mesohyl. Presumably, this degeneration can release some aerothionin and homoaerothionin, which are known to have antibiotic properties. After release from the spherulous cells, these brominated natural products could function (1) within the mesohyl to exclude some types of bacteria or to aggregate ingested bacteria and/or (2) within the boundary layer of the surrounding seawater for defense or offense, as considered in the discussion section. [ABSTRACT FROM AUTHOR]

The predominant low-molecular-mass thiol produced by streptomycetes is a cysteine derivative previously designated as U17 [Newton, G. L., Fahey, R. C., Cohen, G. & Aharonowitz, Y. (1993) J. Bacteriol. 175, 2734–2742]. In this study we report the elucidation of the structure of the monobromobimane derivative of U17, which establishes the structure of U17 as 2-(N-acetylcysteinyl)amido-2-deoxy-α-D-glucopyranosyl-myo-inositol. The presence of the N-acetylcysteine moiety was indicated by formation of N-acetylcysteine-monobromobimane during acid hydrolysis of the monobromobimane derivative of U17. Complete hydrolysis released 1 mol glucosamine/mol cysteine as determined by carbohydrate and amino acid analysis. High-resolution mass spectral analysis gave a precise mass consistent with the molecular formula C27H40N4O14S. Analysis of 13C-NMR, one-dimensional ¹H-NMR and two-dimensional NMR experiments identified the remaining C6H12O6 moiety as .myo-inositol, confirmed the presence of N-acetylcysteine and glucosamine, and established the connectivity of the components. Two chemical properties of this novel thiol make it suitable as an intracellular storage form of cysteine and as an antioxidant thiol. First, it undergoes heavy-metal-ion catalyzed autoxidation at a rate dramatically lower than that for cysteine and markedly lower than that for glutathione or N-acetylcysteine. Secondly, the α-(l→1) glycosidic link between glucosamine and myo-inositol is resistant to acid hydrolysis, hydrolysing at a rate comparable to that of the two amide bonds in the molecule. [ABSTRACT FROM AUTHOR]

The Family Relationship Index (FRI) is a self-report measure that provides an overall index of the quality of the family environment, as well as subscores that reflect family cohesion, expressiveness, and conflict. The current study is based on 53 families who had approached a family service agency for counseling and who had completed an FRI measure prior to intake. The construct validity of the FRI scores was evaluated by comparing them to measures of family functioning provided by experienced family therapists as part of the intake process. Support for the construct validity of the composite index and two of the subscores, Family Cohesion and Family Conflict, was obtained. [ABSTRACT FROM AUTHOR]

This study presents a new analytical framework for combining historical flood data derived from sedimentological records with instrumental river flow data to increase the reliability of flood risk assessments. Historical flood records were established for two catchments through re‐analysis of sedimentological records; the Nant Cwm‐du, a small, steep upland catchment in the Cambrian Mountains of Wales, and a piedmont reach of the River Severn in mid Wales. The proposed framework is based on maximum likelihood and least‐square estimation methods in combination with a Generalised Logistic distribution; this enables the sedimentological data to be combined effectively with existing instrumental river flow data. The results from this study are compared to results obtained using existing industry standard methods based solely on instrumental data. The comparison shows that inclusion of sedimentological data can have an important impact on flood risk estimates, and that the methods are sensitive to assumptions made in the conversion of the sedimentological records into flood flow data. As current industry standard methods for flood risk analysis are known to be highly uncertain, the ability to include additional evidence of past flood events derived from sedimentological records as demonstrated in this study can have a significant impact on flood risk assessments. [ABSTRACT FROM AUTHOR]

This field study of 37 small and medium commercial buildings throughout California obtained information on ventilation rate, temperature, and heating, ventilating, and air-conditioning (HVAC) system characteristics. The study included seven retail establishments; five restaurants; eight offices; two each of gas stations, hair salons, healthcare facilities, grocery stores, dental offices, and fitness centers; and five other buildings. Fourteen (38%) of the buildings either could not or did not provide outdoor air through the HVAC system. The air exchange rate averaged 1.6 (s.d. = 1.7) exchanges per hour and was similar between buildings with and without outdoor air supplied through the HVAC system, indicating that some buildings have significant leakage or ventilation through open windows and doors. Not all buildings had sufficient air exchange to meet ASHRAE 62.1 Standards, including buildings used for fitness centers, hair salons, offices, and retail establishments. The majority of the time, buildings were within the ASHRAE temperature comfort range. Offices were frequently overcooled in the summer. All of the buildings had filters, but over half the buildings had a filter with a minimum efficiency reporting value rating of 4 or lower, which are not very effective for removing fine particles. Practical Implications Most U.S. commercial buildings (96%) are small- to medium-sized, using nearly 18% of the country's energy, and sheltering a large population daily. Little is known about the ventilation systems in these buildings. This study found a wide variety of ventilation conditions, with many buildings failing to meet relevant ventilation standards. Regulators may want to consider implementing more complete building inspections at commissioning and point of sale. [ABSTRACT FROM AUTHOR]