This study characterizes the instrumental record of California climate for the last 170 years.Our goal is to look for hydrologic variability at decadal and longer time scales that would be consistent with paleoclimate...This study characterizes the instrumental record of California climate for the last 170 years.Our goal is to look for hydrologic variability at decadal and longer time scales that would be consistent with paleoclimate estimates of hydrologic variability in California for the last 3000 years.Our study focuses on meteorological summaries of annual precipitation and temperature.The precipitation records go back as far as 1850;the temperature records go back as far as 1880.California hydrologic records show strong variability at the interannual level due to ENSO forcing.They also all show a strong decadal(∼14 yr)cyclicity and evidence for multi-decadal to centennial variability that is consistent with California paleoclimate studies.California temperature records show a long-term warming of 5°F-6°F(2.8°C-3.4°C)associated with global warming,but there is no evidence for a similar long-term trend in hydrologic variability.Long-term Pacific Ocean variability adjacent to central and northern California,Pacific Decadal Oscillation(PDO)and North Pacific Gyre Oscillation(NPGO),show a similar decadal to centennial pattern of variability that we associate with our long-term hydrologic variability.The positive phase of the NPGO and the negative phase of the PDO are associated with the decadal scale(∼14 yr)dry cycles in California for the last 70 years.展开更多
The Neogene interval witnessed three major waves of intercontinental dispersals by carnivoran mammals,mainly migrating from Eurasia to North America but with rare occurrences going in the opposite direction(e.g.,Sthen...The Neogene interval witnessed three major waves of intercontinental dispersals by carnivoran mammals,mainly migrating from Eurasia to North America but with rare occurrences going in the opposite direction(e.g.,Sthenictis,Leptarctus).The timing and composition of dispersers are thought to be controlled by filter-bridge mechanisms,but it is unclear what types of regional conditions promoted occasional dispersals outside of the three major waves.We study and report on new occurrences of small-bodied carnivorans from late Clarendonian-aged Black Hawk Ranch and Cuyama Valley fossil mammal assemblages in California.The relatively late occurrences of the mustelids Sthenictis and Hoplictis and the ailurid Alopecocyon in coastal regions of western North America suggest that nearshore dispersal corridors both facilitate and preserve faunal elements later than they might otherwise occur further inland.The availability of both marine-and terrestrially-derived food resources may be an important factor in allowing coastally dispersing taxa to be accommodated in those ecological communities compared to less heterogenous environments further inland.展开更多
This paper presents a prospective forecast of the locations of the next M_(W)≥6.5 earthquakes in California and Nevada based on the locations and rates of occurrence of M≥4.0 earthquakes during the past 30 years,cal...This paper presents a prospective forecast of the locations of the next M_(W)≥6.5 earthquakes in California and Nevada based on the locations and rates of occurrence of M≥4.0 earthquakes during the past 30 years,called here preshocks.The time period of the forecast is arbitrarily set at 33 years.The forecast faults are the Anza section of the San Jacinto Fault,the Calaveras Fault,the creeping section of the San Andreas Fault,the Maacama Fault,the San Bernardino section of the San Jacinto Fault,and the southern San Andreas Fault,all strike-slip faults in California,and the normal-faulting Wassuk Range Fault in Nevada.The suspected preshocks have occurred randomly along the expected future fault ruptures at rates of at least 0.5 events per year.The temporal history of preshocks for past M≥6.5 earthquakes in California do not indicate when the future mainshock will occur.Outside of California,preshock activity was observed before the 2016 M_(W)7.0 Kumamoto,Japan earthquake,the 2023 M_(W)7.8 Kahramanmaras,Türkiye earthquake,and the 2017 M_(W)6.5 Jiuzhaigou,China earthquake,all strikeslip events,as well as the 2008 M_(W)7.9 Wenchuan,China thrust earthquake.The two mainshocks in China had preshock rates less than 0.5 events per year.By publishing this spatial earthquake forecast,seismologists in the future can evaluate whether or not this forecast was a total success,a total failure,or a partial success.The probability of just one of the forecast events actually taking place during the forecast time period is less than 2%.展开更多
California is one of the major alfalfa (Medicago sativa L) forage-producing states in the U.S, but its production area has decreased significantly in the last couple of decades. Selection of cultivars with high yield ...California is one of the major alfalfa (Medicago sativa L) forage-producing states in the U.S, but its production area has decreased significantly in the last couple of decades. Selection of cultivars with high yield and nutritive value under late-cutting schedule strategy may help identify cultivars that growers can use to maximize yield while maintaining area for sustainable alfalfa production, but there is little information on this strategy. A field study was conducted to determine cumulative dry matter (DM) and nutritive values of 20 semi- and non-fall dormant (FD) ratings (FD 7 and FD 8 - 10, respectively) cultivars under 35-day cut in California’s Central Valley in 2020-2022. Seasonal cumulative DM yields ranged from 6.8 in 2020 to 37.0 Mg·ha−1 in 2021. Four FD 8 - 9 cultivars were the highest yielding with 3-yrs avg. DM greater than the lowest yielding lines by 46%. FD 7 cultivar “715RR” produced the highest crude protein (CP: 240 g·Kg−1) while FD 8 cultivar “HVX840RR” resulted in the highest neutral detergent fiber digestibility (NDFD: 484 g·Kg−1, 7% greater than the top yielding cultivars) but with DM yield intermediate. Yields and NDFD correlated positively but weakly indicating some semi- and non-FD cultivars performing similarly. These results suggest that selecting high yielding cultivars under 35-day cutting schedule strategy can be used as a tool to help growers to maximize yield while achieving good quality forages for sustainable alfalfa production in California’s Central Valley.展开更多
The three largest earthquakes in northern California since 1849 were preceded by increased decadal activity for moderate-size shocks along surrounding nearby faults. Increased seismicity, double-difference precise loc...The three largest earthquakes in northern California since 1849 were preceded by increased decadal activity for moderate-size shocks along surrounding nearby faults. Increased seismicity, double-difference precise locations of earthquakes since 1968, geodetic data and fault offsets for the 1906 great shock are used to re-examine the timing and locations of possible future large earthquakes. The physical mechanisms of regional faults like the Calaveras, Hayward and Sargent, which exhibit creep, differ from those of the northern San Andreas, which is currently locked and is not creeping. Much decadal forerunning activity occurred on creeping faults. Moderate-size earthquakes along those faults became more frequent as stresses in the region increased in the latter part of the cycle of stress restoration for major and great earthquakes along the San Andreas. They may be useful for decadal forecasts. Yearly to decadal forecasts, however, are based on only a few major to great events. Activity along closer faults like that in the two years prior to the 1989 Loma Prieta shock needs to be examined for possible yearly forerunning changes to large plate boundary earthquakes. Geodetic observations are needed to focus on identifying creeping faults close to the San Andreas. The distribution of moderate-size earthquakes increased significantly since 1990 along the Hayward fault but not adjacent to the San Andreas fault to the south of San Francisco compared to what took place in the decades prior to the three major historic earthquakes in the region. It is now clear from a re-examination of the 1989 mainshock that the increased level of moderate-size shocks in the one to two preceding decades occurred on nearby East Bay faults. Double-difference locations of small earthquakes provide structural information about faults in the region, especially their depths. The northern San Andreas fault is divided into several strongly coupled segments based on differences in seismicity.展开更多
This paper presents a comprehensive exploration of the complex phenomenon of homelessness in California,with a specific focus on the state’s three largest cities-Los Angeles,San Francisco,and San Diego.Against the ba...This paper presents a comprehensive exploration of the complex phenomenon of homelessness in California,with a specific focus on the state’s three largest cities-Los Angeles,San Francisco,and San Diego.Against the backdrop of a high cost of living and a housing market strained by insufficient affordable options,the multifaceted nature of social diversity further complicates the landscape,leading to a widespread presence of homelessness that spans both major urban centers and rural regions.Through an in-depth examination of the distinct challenges confronting each city,ranging from housing shortages to intricate social dynamics,this study seeks to illuminate the underlying factors driving homelessness and identify potential avenues for intervention.Moreover,the paper delves into the unique vulnerabilities experienced by certain demographics within the homeless population,including veterans,families with children,and LGBTQ+individuals,highlighting the critical need for targeted solutions tailored to their specific needs.By synthesizing existing research and incorporating firsthand accounts,this research endeavor aims to contribute to a deeper understanding of homelessness in California and inform the development of comprehensive strategies aimed at fostering inclusive,sustainable communities statewide.展开更多
1 Introduction The first legal acupuncture center established in the United States （US） of America was on the east coast in Washington, D.C. in 1972[1-4]. However, the most important state in the acupuncture profes...1 Introduction The first legal acupuncture center established in the United States （US） of America was on the east coast in Washington, D.C. in 1972[1-4]. However, the most important state in the acupuncture profession is on the west coast - in the state of California, which has the longest Iristory of acupuncture practice[5,6] and the largest number of licensed acupuncturists in the US[7].展开更多
The Miocene sandstone deposits in the Southern California region are important hydrocarbon reservoirs. However, their development has been very challenging due to the wide variability in their reservoir quality. These...The Miocene sandstone deposits in the Southern California region are important hydrocarbon reservoirs. However, their development has been very challenging due to the wide variability in their reservoir quality. These sandstones have been studied from three sedimentary basins by petrographic thin section, scanning electron microscope, and X-ray diffraction to evaluate and compare the influence of diagenesis on their reservoir quality in these basins. Four petrofacies, namely P1(sand injectite or dyke), P2(sub-marine fan), P3(turbidite and marine-influenced alluvial fans) and P4(continental sandstones) have been identified. P1 and P2 characterise the sandstones in the San Joaquin forearc basin and are affected by kaolinite and extensive early calcite diagenesis. P3 and P4 delineate the sandstones in the Cajon Valley and Salton Trough strike-slip basins and are dominated by smectite, mixed illite-smectite, early calcite and late calcite diagenesis. Early calcite cement in P3 and P4 is in lower proportion than in P1 and P2. Although the dissolution of these sandstones by acidic fluids did not have a pattern, it, however, has the most considerable influence on P2 creating moldic pores which are expected to increase pore connectivity. The relatively abundant dissolution pores in P2, together with the absence of late authigenic calcite and illite clay in comparison to the other petrofacies studied are likely to make this sandstone facies the best reservoir targets in the Southern California region. These rocks are analogous to producing reservoirs in the region. However, because, petroleum accumulation in these reservoirs are compartmentalized by early calcite cement, maximum recovery using acidified fluids is recommended to dissolve the calcite-filled pores in order to increase connectivity of their pore network and enhance flow potential.展开更多
Resulting from the rising levels of atmospheric carbon, ocean acidification has become a global problem. It has significant impacts on the development, survival, growth and physiology of marine organisms. Therefore, a...Resulting from the rising levels of atmospheric carbon, ocean acidification has become a global problem. It has significant impacts on the development, survival, growth and physiology of marine organisms. Therefore, a high- precision sensor is urgently needed to measure the pH of sea-water. Iridium wire with a diameter of 0.25 mm is used as the substrate, and an Ir/Ir（OH）x pH electrode is prepared by a one-step electrochemical method in a LiOH solution at the room temperature. A scanning electron microscope （SEM） observation reveals that it is coated with nanoscale particles. In laboratory tests, the electrode exhibits a very promising pH response, with an ideal Nernst slope （56.14-59.52）, fast response, good stability and long fife-span in tested pH buffer solutions. For a sea trial, four pH electrodes and one Ag/AgC1 reference electrode are integrated with a self-made chemical sensor, and a profile detection of nearly 70 m is implemented near Newport Harbor, California on August 3, 2015. The results reflect that the pH value measured by the sensor is very close to the data given by Sea-Bird 911 plus CTD, with a difference value ranging from 0.000 075 to 0.064 719. And the sensor shows a better data matching degree in 0-40 m water depth. In addition, the high precision and accuracy of the sensor make it possible to use in the ocean observation field.展开更多
Use of environmentally friendly approaches with the purpose of strengthening soil layers along with finding correlations between the mechanical characteristics of fiber-reinforced soils such as indirect tensile streng...Use of environmentally friendly approaches with the purpose of strengthening soil layers along with finding correlations between the mechanical characteristics of fiber-reinforced soils such as indirect tensile strength(ITS)and California bearing ratio(CBR)and as well as the evaluation of shear strength parameters obtained from the triaxial test would be very effective at geotechnical construction sites.This research was aimed at investigating the influence of natural fibers as sustainable ones including basalt(BS)and bagasse(BG)as well as synthetic polyester(PET)fibers on the strength behavior of clayey soil.To this end,the effects of various fiber contents(0.5%,1%and 2%)and lengths(2.5 mm,5 mm and 7.5 mm)were experimentally evaluated.By conducting ITS and CBR tests,it was found that increasing fiber content and length had a significant influence on CBR and ITS values.Moreover,2%of 7.5 mm-long fibers led to the largest values of CBR and ITS.The CBR values of soil reinforced with PET,BS,and BG fibers were determined as 19.17%,15.43%and 13.16%,respectively.The ITS values of specimens reinforced with PET,BS,and BG fibers were reported as 48.57 kPa,60.7 kPa and 47.48 kPa,respectively.The results of the triaxial compression test revealed that with the addition of BS fibers,the internal friction angle increased by about 100%,and with the addition of PET fibers,the cohesion increased by about 70%.Moreover,scanning electron microscope(SEM)analysis was employed to confirm the findings.The relationship between CBR and ITS values,obtained via statistical analysis and used for the optimum design of road pavement layers,demonstrated that these parameters had high correlation coefficients.The outcomes of multiple linear regression and sensitivity analysis also confirmed that the fiber content had a greater effect on CBR and ITS values than fiber length.展开更多
In this study, we present results from the CASA (Carnegie-Ames-Stanford Approach) model to estimate net primary production (NPP) in grasslands under different management (ranching versus unmanaged) on the Central Coas...In this study, we present results from the CASA (Carnegie-Ames-Stanford Approach) model to estimate net primary production (NPP) in grasslands under different management (ranching versus unmanaged) on the Central Coast of California. The latest model version called CASA Express has been designed to estimate monthly patterns in carbon fixation and plant biomass production using moderate spatial resolution (30 m to 250 m) satellite image data of surface vegetation characteristics. Landsat imagery with 30 m resolution was adjusted by contemporaneous Moderate Resolution Imaging Spectroradiometer (MODIS) data to calibrate the model based on previous CASA research. Results showed annual NPP predictions of between 300 - 450 grams C per square meter for coastal rangeland sites. Irrigation increased the predicted NPP carbon flux of grazed lands by 59 grams C per square meter annually compared to unmanaged grasslands. Low intensity grazing activity appeared to promote higher grass regrowth until June, compared to the ungrazed grassland sites. These modeling methods were shown to be successful in capturing the differing seasonal growing cycles of rangeland forage production across the area of individual ranch properties.展开更多
ccording to the fracture mechanics rupture model of earthquakes put forward by us, several equations to compute tectonic ambient shear stress value τ0 have been derived [equations (1), (2), (3), (5)].τ0 values for i...ccording to the fracture mechanics rupture model of earthquakes put forward by us, several equations to compute tectonic ambient shear stress value τ0 have been derived [equations (1), (2), (3), (5)].τ0 values for intermediate and small earthquakes occurred in Chinese mainland and Southern California have been calculated by use of these equations. The results demonstrate that the level and distribution of τ0 are closely related to the location where large earthquakes will occur, i.e. the region with higher level of τ0 will be prone to occur large earthquakes and the region with lower level will usually occur small earthquakes. According to the spatial distribution of τ0 , the seismic hazard regions or the potential earthquake source regions can in some degree be determined. According to the variation of τ0 with time, the large earthquake occurrence time can be roughly estimated. According to the distribution of τ0 in Southern California and variation with time, three high stress level regions are determined, one (Goldfield area) of them is the present seismic hazard region.展开更多
We use 146 422 P-wave arrival times from 6 347 local earthquakes recorded by the Southern California SeismicNetwork to determine a detailed three-dimensional P-wave velocity structure at 0～35 km depth. We have takeni...We use 146 422 P-wave arrival times from 6 347 local earthquakes recorded by the Southern California SeismicNetwork to determine a detailed three-dimensional P-wave velocity structure at 0～35 km depth. We have takeninto account the Moho depth variations, which were obtained by seismological methods. Checkerboard tests sug-gest that our inversion results are reliable. Our models provide new information on regional geological structuresof Southern California. At shallow depths P-wave velocity structure correlates with surface geological features andexpresses well variations of surface topography of the mountains and basins. The velocity structure at each layer ischaracterized by block structures bounded by large faults. Ventura Basin, Los Angeles Basin, Mojave Desert, Pen-insular Ranges, San Joaquin Valley, Sierra Nevada, and Salton Trough show respectively all-round block. SanAndreas Fault becomes an obvious boundary of the region. To its southwest, the velocity is higher, and there arestrong heterogeneity and deeper seismicity; but to its northeast, the velocity is lower and shows less variation thanto the southwest, the seismicity is shallower. To investigate the effect of the Moho geometry we conducted inver-sions for two cases: one for flat Moho geometry, another for a Moho with lateral depth variations. We found thatthe topography of the Moho greatly affects the velocity structure of the middle and lower crust. When the Mohotopography is considered, a more reasonable tomographic result can be obtained and the resulting 3-D velocitymodel fits the data better.展开更多
Fog deposition is a notable component of the water budget of herbaceous-shrub ecosystems on the central and southern coastal regions of California. This paper presents an analysis of fog water deposition rates and met...Fog deposition is a notable component of the water budget of herbaceous-shrub ecosystems on the central and southern coastal regions of California. This paper presents an analysis of fog water deposition rates and meteorological controls in Big Sur, California. Mesh-screen fog collectors were installed the Brazil Ranch weather station sites to measure fog water during the summer seasons of 2010 and 2011. Fog deposition occurred during 73% of days recorded in 2010 and 87% of days recorded in 2011. The daily average deposition rate was 2.29 L/m2 in 2010 and 3.86 L/m2 in 2011. The meteorological variables which had the greatest influence on prediction of fog deposition were wind speed, wind direction, and the dew-point depression (difference between air temperature and dew point). Based on these results, we hypothesize that high rates of summer fog deposition help sustain the productivity of California coastal vegetation through periods of low rainfall.展开更多
The Santa Cruz Mountain range in northern California is a coastal landscape with a history of extensive forest logging and frequent large wildfires that have recently destroyed numerous residential structures at the w...The Santa Cruz Mountain range in northern California is a coastal landscape with a history of extensive forest logging and frequent large wildfires that have recently destroyed numerous residential structures at the wildland interface. Results from Landsat satellite image time-series analysis since 1984 of the study area within the Los Gatos Creek and Corralitos Creek watersheds showed that none of the severe drought periods since the 1980s have notably inhibited rapid tree and shrub regrowth rates on steep hill slopes burned recently by the 1985 Lexington Fire and the 2008 Summit Fire. In high burn severity areas of both fires, post-fire vegetation types showed a marked increase in shrub cover, mainly at the expense of evergreen tree cover. Most of these low (<3 m), dense stands of evergreen woody species have regenerated in as little as five years from bare charred ground. A combination of Landsat and Laser Altimeter (GLAS) satellite sensor data revealed that exposed south-facing slopes are presently supporting 200 to 240 Mg·ha<sup>-1</sup> of standing woody biomass on the burned areas. This study is the first of its kind to utilize a full 30-year record of Landsat vegetation index data to monitor tree and shrub regrowth after stand-replacing wildfires in California.展开更多
We use precise locations of earthquakes to study forerunning seismic activity to the 1989 Loma Prieta earthquake of magnitude 6.9 to the south of San Francisco, California, USA. Relocated shocks of magnitude 4.3 to 5....We use precise locations of earthquakes to study forerunning seismic activity to the 1989 Loma Prieta earthquake of magnitude 6.9 to the south of San Francisco, California, USA. Relocated shocks of magnitude 4.3 to 5.4 and smaller micro-earthquakes define a distinct zone of nearly the same orientation as the mainshock. That separate zone broke in the 15 months prior to the 1989 mainshock. That feature, which we call the Lake Elsman fault zone, is identified as the site of a prominent intermediate-term (yearly) precursor very close to the coming 1989 mainshock. That zone experienced a relatively large stress decrease during the nearby great earthquake of 1906. From the occurrence of the Lake Elsman shocks, we deduce that stress drop was only restored in the 15 months prior to the 1989 main event. Those stresses are consistent with little forerunning seismic activity in the region after 1906, later increases just before the 1989 mainshock and a decrease in activity thereafter. The southern Santa Cruz mountains segment of the San Andreas Fault zone, the location of the 1989 mainshock, had not been the site of events of magnitude 5 and larger for many decades prior to the occurrence of Lake Elsman earthquakes of magnitude 5.3 and 5.4 in 1988 and 1989. High-preci- sion locations readily available in real-time might be used to monitor similar possible precursory activity very close to the San Andreas and other transform faults.展开更多
文摘This study characterizes the instrumental record of California climate for the last 170 years.Our goal is to look for hydrologic variability at decadal and longer time scales that would be consistent with paleoclimate estimates of hydrologic variability in California for the last 3000 years.Our study focuses on meteorological summaries of annual precipitation and temperature.The precipitation records go back as far as 1850;the temperature records go back as far as 1880.California hydrologic records show strong variability at the interannual level due to ENSO forcing.They also all show a strong decadal(∼14 yr)cyclicity and evidence for multi-decadal to centennial variability that is consistent with California paleoclimate studies.California temperature records show a long-term warming of 5°F-6°F(2.8°C-3.4°C)associated with global warming,but there is no evidence for a similar long-term trend in hydrologic variability.Long-term Pacific Ocean variability adjacent to central and northern California,Pacific Decadal Oscillation(PDO)and North Pacific Gyre Oscillation(NPGO),show a similar decadal to centennial pattern of variability that we associate with our long-term hydrologic variability.The positive phase of the NPGO and the negative phase of the PDO are associated with the decadal scale(∼14 yr)dry cycles in California for the last 70 years.
文摘The Neogene interval witnessed three major waves of intercontinental dispersals by carnivoran mammals,mainly migrating from Eurasia to North America but with rare occurrences going in the opposite direction(e.g.,Sthenictis,Leptarctus).The timing and composition of dispersers are thought to be controlled by filter-bridge mechanisms,but it is unclear what types of regional conditions promoted occasional dispersals outside of the three major waves.We study and report on new occurrences of small-bodied carnivorans from late Clarendonian-aged Black Hawk Ranch and Cuyama Valley fossil mammal assemblages in California.The relatively late occurrences of the mustelids Sthenictis and Hoplictis and the ailurid Alopecocyon in coastal regions of western North America suggest that nearshore dispersal corridors both facilitate and preserve faunal elements later than they might otherwise occur further inland.The availability of both marine-and terrestrially-derived food resources may be an important factor in allowing coastally dispersing taxa to be accommodated in those ecological communities compared to less heterogenous environments further inland.
文摘This paper presents a prospective forecast of the locations of the next M_(W)≥6.5 earthquakes in California and Nevada based on the locations and rates of occurrence of M≥4.0 earthquakes during the past 30 years,called here preshocks.The time period of the forecast is arbitrarily set at 33 years.The forecast faults are the Anza section of the San Jacinto Fault,the Calaveras Fault,the creeping section of the San Andreas Fault,the Maacama Fault,the San Bernardino section of the San Jacinto Fault,and the southern San Andreas Fault,all strike-slip faults in California,and the normal-faulting Wassuk Range Fault in Nevada.The suspected preshocks have occurred randomly along the expected future fault ruptures at rates of at least 0.5 events per year.The temporal history of preshocks for past M≥6.5 earthquakes in California do not indicate when the future mainshock will occur.Outside of California,preshock activity was observed before the 2016 M_(W)7.0 Kumamoto,Japan earthquake,the 2023 M_(W)7.8 Kahramanmaras,Türkiye earthquake,and the 2017 M_(W)6.5 Jiuzhaigou,China earthquake,all strikeslip events,as well as the 2008 M_(W)7.9 Wenchuan,China thrust earthquake.The two mainshocks in China had preshock rates less than 0.5 events per year.By publishing this spatial earthquake forecast,seismologists in the future can evaluate whether or not this forecast was a total success,a total failure,or a partial success.The probability of just one of the forecast events actually taking place during the forecast time period is less than 2%.
文摘California is one of the major alfalfa (Medicago sativa L) forage-producing states in the U.S, but its production area has decreased significantly in the last couple of decades. Selection of cultivars with high yield and nutritive value under late-cutting schedule strategy may help identify cultivars that growers can use to maximize yield while maintaining area for sustainable alfalfa production, but there is little information on this strategy. A field study was conducted to determine cumulative dry matter (DM) and nutritive values of 20 semi- and non-fall dormant (FD) ratings (FD 7 and FD 8 - 10, respectively) cultivars under 35-day cut in California’s Central Valley in 2020-2022. Seasonal cumulative DM yields ranged from 6.8 in 2020 to 37.0 Mg·ha−1 in 2021. Four FD 8 - 9 cultivars were the highest yielding with 3-yrs avg. DM greater than the lowest yielding lines by 46%. FD 7 cultivar “715RR” produced the highest crude protein (CP: 240 g·Kg−1) while FD 8 cultivar “HVX840RR” resulted in the highest neutral detergent fiber digestibility (NDFD: 484 g·Kg−1, 7% greater than the top yielding cultivars) but with DM yield intermediate. Yields and NDFD correlated positively but weakly indicating some semi- and non-FD cultivars performing similarly. These results suggest that selecting high yielding cultivars under 35-day cutting schedule strategy can be used as a tool to help growers to maximize yield while achieving good quality forages for sustainable alfalfa production in California’s Central Valley.
文摘The three largest earthquakes in northern California since 1849 were preceded by increased decadal activity for moderate-size shocks along surrounding nearby faults. Increased seismicity, double-difference precise locations of earthquakes since 1968, geodetic data and fault offsets for the 1906 great shock are used to re-examine the timing and locations of possible future large earthquakes. The physical mechanisms of regional faults like the Calaveras, Hayward and Sargent, which exhibit creep, differ from those of the northern San Andreas, which is currently locked and is not creeping. Much decadal forerunning activity occurred on creeping faults. Moderate-size earthquakes along those faults became more frequent as stresses in the region increased in the latter part of the cycle of stress restoration for major and great earthquakes along the San Andreas. They may be useful for decadal forecasts. Yearly to decadal forecasts, however, are based on only a few major to great events. Activity along closer faults like that in the two years prior to the 1989 Loma Prieta shock needs to be examined for possible yearly forerunning changes to large plate boundary earthquakes. Geodetic observations are needed to focus on identifying creeping faults close to the San Andreas. The distribution of moderate-size earthquakes increased significantly since 1990 along the Hayward fault but not adjacent to the San Andreas fault to the south of San Francisco compared to what took place in the decades prior to the three major historic earthquakes in the region. It is now clear from a re-examination of the 1989 mainshock that the increased level of moderate-size shocks in the one to two preceding decades occurred on nearby East Bay faults. Double-difference locations of small earthquakes provide structural information about faults in the region, especially their depths. The northern San Andreas fault is divided into several strongly coupled segments based on differences in seismicity.
文摘This paper presents a comprehensive exploration of the complex phenomenon of homelessness in California,with a specific focus on the state’s three largest cities-Los Angeles,San Francisco,and San Diego.Against the backdrop of a high cost of living and a housing market strained by insufficient affordable options,the multifaceted nature of social diversity further complicates the landscape,leading to a widespread presence of homelessness that spans both major urban centers and rural regions.Through an in-depth examination of the distinct challenges confronting each city,ranging from housing shortages to intricate social dynamics,this study seeks to illuminate the underlying factors driving homelessness and identify potential avenues for intervention.Moreover,the paper delves into the unique vulnerabilities experienced by certain demographics within the homeless population,including veterans,families with children,and LGBTQ+individuals,highlighting the critical need for targeted solutions tailored to their specific needs.By synthesizing existing research and incorporating firsthand accounts,this research endeavor aims to contribute to a deeper understanding of homelessness in California and inform the development of comprehensive strategies aimed at fostering inclusive,sustainable communities statewide.
文摘1 Introduction The first legal acupuncture center established in the United States （US） of America was on the east coast in Washington, D.C. in 1972[1-4]. However, the most important state in the acupuncture profession is on the west coast - in the state of California, which has the longest Iristory of acupuncture practice[5,6] and the largest number of licensed acupuncturists in the US[7].
基金the University of Aberdeen for an Elphinstone PhD ScholarshipNiger Delta Development Commission(NDDC)for financial assistance。
文摘The Miocene sandstone deposits in the Southern California region are important hydrocarbon reservoirs. However, their development has been very challenging due to the wide variability in their reservoir quality. These sandstones have been studied from three sedimentary basins by petrographic thin section, scanning electron microscope, and X-ray diffraction to evaluate and compare the influence of diagenesis on their reservoir quality in these basins. Four petrofacies, namely P1(sand injectite or dyke), P2(sub-marine fan), P3(turbidite and marine-influenced alluvial fans) and P4(continental sandstones) have been identified. P1 and P2 characterise the sandstones in the San Joaquin forearc basin and are affected by kaolinite and extensive early calcite diagenesis. P3 and P4 delineate the sandstones in the Cajon Valley and Salton Trough strike-slip basins and are dominated by smectite, mixed illite-smectite, early calcite and late calcite diagenesis. Early calcite cement in P3 and P4 is in lower proportion than in P1 and P2. Although the dissolution of these sandstones by acidic fluids did not have a pattern, it, however, has the most considerable influence on P2 creating moldic pores which are expected to increase pore connectivity. The relatively abundant dissolution pores in P2, together with the absence of late authigenic calcite and illite clay in comparison to the other petrofacies studied are likely to make this sandstone facies the best reservoir targets in the Southern California region. These rocks are analogous to producing reservoirs in the region. However, because, petroleum accumulation in these reservoirs are compartmentalized by early calcite cement, maximum recovery using acidified fluids is recommended to dissolve the calcite-filled pores in order to increase connectivity of their pore network and enhance flow potential.
基金The Key Laboratory Project of State Oceanic Administration for Marine Ecosystem and Biogeochemistry of China under contract No.529101-X21601the Foundation from Wendy Schmidt Ocean Health XPRIZE and the Southern California Coastal Water Research Project
文摘Resulting from the rising levels of atmospheric carbon, ocean acidification has become a global problem. It has significant impacts on the development, survival, growth and physiology of marine organisms. Therefore, a high- precision sensor is urgently needed to measure the pH of sea-water. Iridium wire with a diameter of 0.25 mm is used as the substrate, and an Ir/Ir（OH）x pH electrode is prepared by a one-step electrochemical method in a LiOH solution at the room temperature. A scanning electron microscope （SEM） observation reveals that it is coated with nanoscale particles. In laboratory tests, the electrode exhibits a very promising pH response, with an ideal Nernst slope （56.14-59.52）, fast response, good stability and long fife-span in tested pH buffer solutions. For a sea trial, four pH electrodes and one Ag/AgC1 reference electrode are integrated with a self-made chemical sensor, and a profile detection of nearly 70 m is implemented near Newport Harbor, California on August 3, 2015. The results reflect that the pH value measured by the sensor is very close to the data given by Sea-Bird 911 plus CTD, with a difference value ranging from 0.000 075 to 0.064 719. And the sensor shows a better data matching degree in 0-40 m water depth. In addition, the high precision and accuracy of the sensor make it possible to use in the ocean observation field.
文摘Use of environmentally friendly approaches with the purpose of strengthening soil layers along with finding correlations between the mechanical characteristics of fiber-reinforced soils such as indirect tensile strength(ITS)and California bearing ratio(CBR)and as well as the evaluation of shear strength parameters obtained from the triaxial test would be very effective at geotechnical construction sites.This research was aimed at investigating the influence of natural fibers as sustainable ones including basalt(BS)and bagasse(BG)as well as synthetic polyester(PET)fibers on the strength behavior of clayey soil.To this end,the effects of various fiber contents(0.5%,1%and 2%)and lengths(2.5 mm,5 mm and 7.5 mm)were experimentally evaluated.By conducting ITS and CBR tests,it was found that increasing fiber content and length had a significant influence on CBR and ITS values.Moreover,2%of 7.5 mm-long fibers led to the largest values of CBR and ITS.The CBR values of soil reinforced with PET,BS,and BG fibers were determined as 19.17%,15.43%and 13.16%,respectively.The ITS values of specimens reinforced with PET,BS,and BG fibers were reported as 48.57 kPa,60.7 kPa and 47.48 kPa,respectively.The results of the triaxial compression test revealed that with the addition of BS fibers,the internal friction angle increased by about 100%,and with the addition of PET fibers,the cohesion increased by about 70%.Moreover,scanning electron microscope(SEM)analysis was employed to confirm the findings.The relationship between CBR and ITS values,obtained via statistical analysis and used for the optimum design of road pavement layers,demonstrated that these parameters had high correlation coefficients.The outcomes of multiple linear regression and sensitivity analysis also confirmed that the fiber content had a greater effect on CBR and ITS values than fiber length.
文摘In this study, we present results from the CASA (Carnegie-Ames-Stanford Approach) model to estimate net primary production (NPP) in grasslands under different management (ranching versus unmanaged) on the Central Coast of California. The latest model version called CASA Express has been designed to estimate monthly patterns in carbon fixation and plant biomass production using moderate spatial resolution (30 m to 250 m) satellite image data of surface vegetation characteristics. Landsat imagery with 30 m resolution was adjusted by contemporaneous Moderate Resolution Imaging Spectroradiometer (MODIS) data to calibrate the model based on previous CASA research. Results showed annual NPP predictions of between 300 - 450 grams C per square meter for coastal rangeland sites. Irrigation increased the predicted NPP carbon flux of grazed lands by 59 grams C per square meter annually compared to unmanaged grasslands. Low intensity grazing activity appeared to promote higher grass regrowth until June, compared to the ungrazed grassland sites. These modeling methods were shown to be successful in capturing the differing seasonal growing cycles of rangeland forage production across the area of individual ranch properties.
文摘ccording to the fracture mechanics rupture model of earthquakes put forward by us, several equations to compute tectonic ambient shear stress value τ0 have been derived [equations (1), (2), (3), (5)].τ0 values for intermediate and small earthquakes occurred in Chinese mainland and Southern California have been calculated by use of these equations. The results demonstrate that the level and distribution of τ0 are closely related to the location where large earthquakes will occur, i.e. the region with higher level of τ0 will be prone to occur large earthquakes and the region with lower level will usually occur small earthquakes. According to the spatial distribution of τ0 , the seismic hazard regions or the potential earthquake source regions can in some degree be determined. According to the variation of τ0 with time, the large earthquake occurrence time can be roughly estimated. According to the distribution of τ0 in Southern California and variation with time, three high stress level regions are determined, one (Goldfield area) of them is the present seismic hazard region.
基金Japan Society for Promotion of Science，Chinese State Key Program of Basic Research on Mechanisms and Predictions of Strong Continental Earthquakes
文摘We use 146 422 P-wave arrival times from 6 347 local earthquakes recorded by the Southern California SeismicNetwork to determine a detailed three-dimensional P-wave velocity structure at 0～35 km depth. We have takeninto account the Moho depth variations, which were obtained by seismological methods. Checkerboard tests sug-gest that our inversion results are reliable. Our models provide new information on regional geological structuresof Southern California. At shallow depths P-wave velocity structure correlates with surface geological features andexpresses well variations of surface topography of the mountains and basins. The velocity structure at each layer ischaracterized by block structures bounded by large faults. Ventura Basin, Los Angeles Basin, Mojave Desert, Pen-insular Ranges, San Joaquin Valley, Sierra Nevada, and Salton Trough show respectively all-round block. SanAndreas Fault becomes an obvious boundary of the region. To its southwest, the velocity is higher, and there arestrong heterogeneity and deeper seismicity; but to its northeast, the velocity is lower and shows less variation thanto the southwest, the seismicity is shallower. To investigate the effect of the Moho geometry we conducted inver-sions for two cases: one for flat Moho geometry, another for a Moho with lateral depth variations. We found thatthe topography of the Moho greatly affects the velocity structure of the middle and lower crust. When the Mohotopography is considered, a more reasonable tomographic result can be obtained and the resulting 3-D velocitymodel fits the data better.
文摘Fog deposition is a notable component of the water budget of herbaceous-shrub ecosystems on the central and southern coastal regions of California. This paper presents an analysis of fog water deposition rates and meteorological controls in Big Sur, California. Mesh-screen fog collectors were installed the Brazil Ranch weather station sites to measure fog water during the summer seasons of 2010 and 2011. Fog deposition occurred during 73% of days recorded in 2010 and 87% of days recorded in 2011. The daily average deposition rate was 2.29 L/m2 in 2010 and 3.86 L/m2 in 2011. The meteorological variables which had the greatest influence on prediction of fog deposition were wind speed, wind direction, and the dew-point depression (difference between air temperature and dew point). Based on these results, we hypothesize that high rates of summer fog deposition help sustain the productivity of California coastal vegetation through periods of low rainfall.
文摘The Santa Cruz Mountain range in northern California is a coastal landscape with a history of extensive forest logging and frequent large wildfires that have recently destroyed numerous residential structures at the wildland interface. Results from Landsat satellite image time-series analysis since 1984 of the study area within the Los Gatos Creek and Corralitos Creek watersheds showed that none of the severe drought periods since the 1980s have notably inhibited rapid tree and shrub regrowth rates on steep hill slopes burned recently by the 1985 Lexington Fire and the 2008 Summit Fire. In high burn severity areas of both fires, post-fire vegetation types showed a marked increase in shrub cover, mainly at the expense of evergreen tree cover. Most of these low (<3 m), dense stands of evergreen woody species have regenerated in as little as five years from bare charred ground. A combination of Landsat and Laser Altimeter (GLAS) satellite sensor data revealed that exposed south-facing slopes are presently supporting 200 to 240 Mg·ha<sup>-1</sup> of standing woody biomass on the burned areas. This study is the first of its kind to utilize a full 30-year record of Landsat vegetation index data to monitor tree and shrub regrowth after stand-replacing wildfires in California.
文摘We use precise locations of earthquakes to study forerunning seismic activity to the 1989 Loma Prieta earthquake of magnitude 6.9 to the south of San Francisco, California, USA. Relocated shocks of magnitude 4.3 to 5.4 and smaller micro-earthquakes define a distinct zone of nearly the same orientation as the mainshock. That separate zone broke in the 15 months prior to the 1989 mainshock. That feature, which we call the Lake Elsman fault zone, is identified as the site of a prominent intermediate-term (yearly) precursor very close to the coming 1989 mainshock. That zone experienced a relatively large stress decrease during the nearby great earthquake of 1906. From the occurrence of the Lake Elsman shocks, we deduce that stress drop was only restored in the 15 months prior to the 1989 main event. Those stresses are consistent with little forerunning seismic activity in the region after 1906, later increases just before the 1989 mainshock and a decrease in activity thereafter. The southern Santa Cruz mountains segment of the San Andreas Fault zone, the location of the 1989 mainshock, had not been the site of events of magnitude 5 and larger for many decades prior to the occurrence of Lake Elsman earthquakes of magnitude 5.3 and 5.4 in 1988 and 1989. High-preci- sion locations readily available in real-time might be used to monitor similar possible precursory activity very close to the San Andreas and other transform faults.
