360 research outputs found

    Foreshock, Main Shock, and Larger Aftershocks of the Borrego Mountain Earthquake

    Get PDF
    The Borrego Mountain earthquake, magnitude 6.4, occurred at 02:28:59.1 G.m.t. on April 9, 1968 and has been assigned a hypocenter at 33°11.4' N., 116°07.7' W., h=11.1 km. The focal-mechanism solution indicates right-lateral slip on a fault striking N. 48° W. and dipping 83° NE., which is consistent with the field observations of faulting and the regional tectonic framework. A single foreshock of magnitude 3.7 preceded the main shock by one minute, but no other precursory activity has been identified. During the year following the event, 135 aftershocks of magnitude 3.0 and greater have been identified and located, outlining a broad zone of activity centered on but displaced 2-3 km northeast of the 33-km-long surface rupture on the Coyote Creek fault. Fracturing at depth during the aftershock period evidently occurred throughout the width of the San Jacinto fault zone, but initial surface faulting was localized along the Coyote Creek fault at the zone's southwestern margin. The area of aftershock activity enlarged progressively with time, and the region of the original epicenter became relatively inactive late in the aftershock period, leading to a doughnut-shaped epicentral distribution of late aftershocks. Inasmuch as the epicenter of the main shock was roughly midway along the zone of aftershock activity, the faulting presumably was bilateral. This kind of faulting is unusual in California

    Theoretical studies of optimal light delivery for tumor treatment

    Get PDF
    Optimal laser light delivery into turbid biological tissue was studied using MOnte Carlo simulations. The goal was to efficiently deliver maximum amount of optical power into buried tumors being treated while avoiding damage to normal tissue caused by strong optical power deposition underneath the tissue surface illuminated by the laser beam. The buried tumors were considered to have much higher absorption than the surrounding normal tissue via selective uptake of absorption-enhancement dye by the tumor. The power delivering efficiency to buried tumors was investigated for various diameters of the laser beam. An optimal beam diameter was estimated to achieve the maximum produce of the power coupling efficiency and the power delivered to the buried tumor. The distribution of power deposition was simulated for single beam delivery and multiple beam delivery as well. The simulated results showed that with an appropriate dye enhancement and an optimal laser delivery configuration, a high selectivity for laser treatment of tumor could be achieved

    Optimal beam size for light delivery to absorption-enhanced tumors buried in biological tissues and effect of multiple-beam delivery: a Monte Carlo study

    Get PDF
    Optimal laser light delivery into turbid biological tissues was studied by using Monte Carlo simulations based on the delta-scattering technique. The goal was to deliver efficiently the maximum amount of optical power into buried tumors being treated while avoiding potential damage to normal tissue caused by strong optical power deposition underneath the tissue surface illuminated by the laser beam. The buried tumors were considered to have much higher absorption than the surrounding normal tissue because of selective uptake of the absorption-enhancement dye. The power delivering efficiency to buried tumors was investigated for various diameters of the laser beam. An optimal beam diameter was estimated to achieve the maximum product of the power coupling efficiency and the power delivered to the buried tumor. The distribution of power deposition was simulated for single-beam delivery and multiple-beam delivery as well. The simulated results showed that with an appropriate dye enhancement and an optimal laser delivery configuration, a high selectivity for laser treatment of tumor could be achieved

    Paramedics’ perceptions of job demands and resources in Finnish emergency medical services : a qualitative study

    Get PDF
    Publisher Copyright: © 2022, The Author(s).Background: Paramedics’ fatigue is rising. Stress factors show increased risk for burnout, fatigue, leaving the profession, decreased performance and risk for patient safety. Meanwhile, paramedics’ strong community of practice, autonomy and a sense of professional respect are important factors in forming psychological resilience. We aimed to explore Finnish paramedics’ perceptions of job demands and resources. Methods: Our study design was descriptive, inductive with a constructivist approach. Using reflexive thematic analysis, we analyse open-ended questions, from a web-based survey and essays written by Finnish paramedic masters-degree students. The study followed the SRQR checklist. Results: We identified paramedics’ job demands as stress from a high workload, environmental factors and emotional burden. Performance expectations and a sense of inadequacy were further noted, as well as an organizational culture of hardiness, presenting lack of support and sense of inequality. Paramedics’ job resources were pressure management strategies, which were expressed as positive coping mechanisms, agency to affect workload and professional self-actualization, expressed as psychologically safe work community, professional pride and internal drive to professional development. Conclusions: Finnish paramedics exhibit resources and demands related to uncertainty and emotional burden as well as cultural hardiness and psychological safety in communities. Patient or public contribution: This study was done based on survey data collected and analysed by the authors. No patient or public contribution was utilized for this study.Peer reviewe

    The Desert Hot Springs earthquakes and their tectonic environment

    Get PDF
    The Desert Hot Springs earthquake of December 4, 1948, was one of the larger recorded earthquakes of southern California, and its aftershocks have continued into 1957. The assigned epicenter is 33° 56'.4 N, 116° 23'.1 W; origin time, 15:43:16.7 P.S.T.; magnitude 6 1/2. Arrival times at local and distant stations are consistent with existing travel-time curves, except for anomalous S – P intervals at very near-by temporary stations; these unexplained anomalies cannot be attributed to varying depth of focus. Epicenters of the 72 aftershocks that have been accurately located are concentrated in a zone 18 km. long, parallel to the Mission Creek fault trace indicated by older scarps, but 5 km. north of it. Aftershock activity is markedly concentrated toward the two ends of this line. Location of the main shock suggests that fracturing started near the southeast end and progressed northwest-ward. The ground surface was not broken, except by landslides. Offset of the line of seismic activity from the trace of the Mission Creek fault suggests that the fault plane dips north. This attitude is substantiated not only by field observations, but also by first motions at stations within 6° of the epicenter, which require a combination of thrust-slip and right lateral-slip on a fault dipping north less than 66°. Inasmuch as this fault is not parallel to regional San Andreas trend, such oblique displacement is reasonable and is consistent with the tectonic pattern of other faults in this region. Five groups of earthquakes represent more than 85 per cent of the total strain release since 1933 in the 3,000 sq. km. area surrounding Desert Hot Springs. These earthquakes, in addition to the Desert Hot Springs shock, are: Morongo Valley (1947), Kitching Peak (1944), Covington Flat (1940), and San Gorgonio Mountain (1935); all are associated with known faults. The Morongo Valley earthquakes probably represent fracturing on the segment of the Mission Creek fault adjacent to that broken during the subsequent Desert Hot Springs shock

    Measurement of tissue optical properties and modeling of optimal light delivery for tumor treatment

    Get PDF
    Oblique-incidence reflectometry was used to measure the optical properties of rat tumors with injected absorption- enhancement dye. The measured optical properties were used to model light delivery into the tissues for optimal therapeutic effects. The goal was to efficiently deliver the maximum amount of optical power into buried tumors being treated while avoiding potential damage to normal tissue caused by strong optical power deposition underneath the tissue surface illuminated by the laser beam. The distribution of power deposition was simulated for single beam delivery and multiple beam delivery as well. The simulated results showed that with an appropriate dye enhancement and an optimal laser delivery configuration, a high selectivity for laser treatment of tumors could be achieved

    Local Bulletin of Earthquakes in the Southern California Region 1 January 1963 to 31 December 1966

    Get PDF
    The Local Bulletin of the Pasadena Seismological Laboratory has been issued regularly since the beginning of 1934, and the present Bulletin covers the four-year period from 1 January 1963 to 31 December 1966

    Social behaviour of pigs

    Get PDF
    Improper social behavior development brings problems in later social life. Several time points are known to be crucial for the development and in other words, susceptible to interruptions during those time points. In conventional pigs, those time points could be categorized to three interaction periods, the period for piglet-sow interaction (suckling), between littermates interaction (before weaning), social interaction with other littermates (after weaning). In this research, 4 cages (51 pigs) of pigs were observed for figuring out circadian rhythm and social behavior pattern. In group observation, the circadian rhythm of conventional pigs was established as a pair of active hours in early morning and early evening. Over three recordings of three different time points of day 10, 14 and 24, the behavior status ‘active’ increased with their physical developmental status and this is suggesting increase in potential social behaviors. In individual observation, the environmental change induced by maternal separation and mixing of other littermates resulted change in specific social behavioral pattern. Additional second individual observation also showed changed social behavioral pattern. The results in this research could suggest the needs for proper social behavioral development according to the critical time points and social environmental changes so that prevent existing behavioral problems and improve the welfare of conventional farm pigs

    Relationship between seismicity and geologic structure in the Southern California region

    Get PDF
    Data from 10,126 earthquakes that occurred in the southern California region between 1934 and 1963 have been synthesized in the attempt to understand better their relationship to regional geologic structure, which is here dominated by a system of faults related mainly to the San Andreas system. Most of these faults have been considered “active” from physiographic evidence, but both geologic and short-term seismic criteria for “active” versus “inactive” faults are generally inadequate. Of the large historic earthquakes that have been associated with surficial fault displacements, most and perhaps all were on major throughgoing faults having a previous history of extensive Quaternary displacements. The same relationship holds for most earthquakes down to magnitude 6.0, but smaller shocks are much more randomly spread throughout the region, and most are not clearly associated with any mappable surficial faults. Virtually all areas of high seismicity in this region fall within areas having numerous Quaternary fault scarps, but not all intensely faulted areas have been active during this particular 29-year period. Strain-release maps show high activity in the Salton trough, the Agua Blanca-San Miguel fault region of Baja California, most of the Transverse Ranges, the central Mojave Desert, and the Owens Valley-southern Sierra Nevada region. Areas of low activity include the San Diego region, the western and easternmost Mojave Desert, and the southern San Joaquin Valley. Because these areas also generally lack Quaternary faults, they probably represent truly stable blocks. In contrast, regions of low seismicity during this period that show widespread Quaternary faulting include the San Andreas fault within and north of the Transverse Ranges, the Garlock fault, and several quiescent zones along major faults within otherwise very active regions. We suspect that seismic quiescence in large areas may be temporary and that they represent likely candidates for future large earthquakes. Without more adequate geodetic control, however, it is not known that strain is necessarily accumulating in all of these areas. Even in areas of demonstrated regional shearing, the relative importance of elastic strain accumulation versus fault slippage is unknown, although slippage is clearly not taking place everywhere along major “active” faults of the region. Recurrence curves of earthquake magnitude versus frequency are presented for six tectonically distinct 8500-km^2 areas within the region. They suggest either that an area of this small size or that a sample period of only 29 years is insufficient for establishing valid recurrence expectancies; on this basis the San Andreas fault would be the least hazardous zone of the region, because only a few small earthquakes have occurred here during this particular period. Although recurrence expectancies apparently break down for these smaller areas, historic records suggest that the calculated recurrence rate of 52 years for M = 8.0 earthquakes for the entire region may well be valid. Neither a fault map nor the 29-year seismic record provides sufficient information for detailed seismic zoning maps; not only are many other geologic factors important in determining seismic risk, but the strain-release or epicenter map by itself may give a partially reversed picture of future seismic expectance. Seismic and structural relationships suggest that the fault theory still provides the most satisfactory explanation of earthquakes in this region
    • 

    corecore