bluuebunny/crossref_metadata_2025_split huggingface dataset:
Çocuk Kardiyoloji Polikliniğine Akut Göğüs Ağrısı Nedeniyle Başvuran Çocukların Etiyolojik Açıdan Değerlendirilmesi
Authors: YURDAKUL ERTÜRK Emine , KASAR Taner 
Published: July 2021

Amaç: Azollerin profilaksi veya tedavi amacıyla yaygın ve tekrarlayan kullanımı Candida albicans (C.albicans) türlerinde direnç gelişimine yol açmıştır.
Gereç ve Yöntemler: Bu çalışmada, steril vücut sıvısı kültürlerinden izole edilen C.albicans izolatlarının flukonazol, itrakonazol ve vorikonazole in vitro direnç oranlarının belirlenmesi amaçlanmıştır. Tür düzeyinde tanımlama, geleneksel tanı yöntemleri ve BD Phoenix 100 (BD, ABD) otomatik tanımlama sistemi kullanılarak yapıldı. Antifungal duyarlılık testi, %2 glukoz içeren RPMI kullanılarak mikrodilüsyon yöntemiyle değerlendirildi. Triazoller olan flukonazol, itrakonazol ve vorikonazol için bulanıklığın belirgin (≥%50) olarak azaldığı kuyucuktaki konsantrasyon, MİK50 değeri olarak belirlendi. Çalışmada kontrol
suş olarak C.albicans ATCC 90028 kullanıldı.
Bulgular: C.albicans izolatlarının %88.2’si (n=45) yoğun bakım ünitelerinden alınan örneklerden izole edildi. Örneklerin 26 (%50.9)’sı yaş ortalaması 68.6±18.29 yıl olan kadın hastalardan, 25 (%49)’i yaş ortalaması 62.22±21.08 yıl olan erkek hastalardan alındı. İzolatların 48 (%94.1)’i kan,1 (%1.96)’i beyin omurilik sıvısı, 1 (%1.96)’i steril vücut sıvısı, 1(%1.96)’i peritoneal sıvı kültüründen tanımlandı. Antifungal duyarlılık test sonuçlarına göre türlerin 7 (%12.2)’si flukonazol, 14 (%27.4)’ü itrakonazol ve 5 (%9.8)’i vorikonazole dirençli bulundu. Toplam 6 (%11.7) örnekte ise çapraz dirence rastlandı.
Sonuç: C.albicans izolatlarında triazollere direncin yanısıra diğer azollere karşı da çapraz direnç saptanmıştır. Bu nedenle uygun tedavi için antifungal duyarlılık test sonuçları dikkate alınmalıdır.
Geometry of the Juan de Fuca plate beneath Washington and northern Oregon from seismicity
Authors: Weaver Craig S. , Baker Glenn E. 
Published: July 2021

Abstract
Earthquake hypocenters within the subducting Juan de Fuca plate beneath Washington and northern Oregon are interpreted as showing that the direction of plate dip changes from northeast beneath the Puget Sound region to east-southeast beneath southwestern Washington. The shallowest hypocenters within the Juan de Fuca plate are between 30- to 40-km depth, and the distribution of these events strikes north-northeast from near the mouth of the Columbia River to the northern Olympic Mountains. The distribution of hypocenters between 40 to 50 km generally strikes parallel with the shallowest events, but shows a significant broadening beneath the eastern Olympic Mountains and Puget Sound. Events with depths greater than 50 km south of the 1965 Seattle earthquake (mb = 6.5) strike north-northeast, approximately parallel with the shallower distributions; however, north of this event, the distribution of these deeper hypocenters strikes northwest. This change in the distribution of earthquake hypocenters reflects an upward arching of the Juan de Fuca plate plate beneath Puget Sound compared with the depth of the plate beneath southwestern Washington. The T axis calculated for the 1949 South Puget Sound earthquake (MS = 7.1) is oriented to the southeast, and the 20° plunge of the T axis is in good agreement with the plate dip angle determined from the earthquake hypocenters. We conclude that the 1949 earthquake resulted at least in part from down-dip tensional forces within the subducting Juan de Fuca plate. One consequence of the change in the direction of plate dip is that volcanic front in Washington is everywhere perpendicular to the dip of the Juan de Fuca plate.
Failure of self-similarity for large (Mω&gt; 814) earthquakes
Authors: Hartzell Stephen H. , Heaton Thomas H. 
Published: July 2021

AbstractWe compare teleseismic P-wave records for earthquakes in the magnitude range from 6.0 to 9.5 with synthetics for a self-similar, ω2 source model and conclude that the energy radiated by very large earthquakes (Mw &gt; 814) is not self-similar to that radiated from smaller earthquakes (Mw &lt; 814). Furthermore, in the period band from 2 sec to several tens of seconds, we conclude that large subduction earthquakes have an average spectral decay rate of ω-1.5. This spectral decay rate is consistent with a previously noted tendency of the ω2 model to overestimate Ms for large earthquakes.
High-frequency spectral scaling of a main shock/ aftershock sequence near the Norwegian coast
Authors: Chael Eric P. , Kromer Richard P. 
Published: July 2021

AbstractA high-frequency seismic element was recently added to the NORESS regional array in Norway. This system can monitor seismic signals at frequencies up to 50 Hz. In February 1986, the high-frequency seismic element recorded an mbLg 4.7 main shock and several aftershocks which occurred 420 km northwest of NORESS, off Norway's western coast. These events produced high-frequency signals which were well above the background noise at the station. P-wave spectra of these events scale in a manner consistent with the ω-square, constant-stress-drop source model. The data do not require any change in this scaling to magnitudes (mbLg) below 2, in contrast to previous reports that constant-stress-drop scaling breaks down at smaller magnitudes.
The 1918 and 1957 Vancouver Island earthquakes
Authors: Cassidy John F. , Ellis Robert M. , Rogers Garry C. 
Published: July 2021

AbstractSince 1918, six significant earthquakes (5.2 &lt; M &lt; 7.2) have occurred in the region of central Vancouver Island where the Juan de Fuca, Explorer, and America plates interact. In this study, two of the largest earthquakes are examined in detail: the 1918 (MS ≃ 7) and the 1957 (MS ≃ 6) events.The preferred location of the 1918 earthquake is on Vancouver Island at 49.44°N, 126.22°W, with a focal depth of 15 km. Magnitudes determined are MS = 6.9 ± 0.3 and mb = 7.2 ± 0.4. Analysis of surface waves suggests this is a predominantly strike-slip earthquake occurring along either a NNW- or an ENE-striking fault. The seismic moment is estimated as 7.40 × 1025 dyne-cm and the stress drop to be 122 bars.The 1957 earthquake has been relocated on the continental shelf west of Vancouver Island at 49.64°N, 127.00°W, with a focal depth of 30 km. Magnitudes determined are MS = 5.9 ± 0.2 and mb = 6.3 ± 0.3. Surface wave and P-nodal analyses indicate that this is a predominantly strike-slip earthquake; either dextral along an NNW-striking fault, or sinistral along a ENE-striking fault. The seismic moment is estimated as 8.14 × 1024 dyne-cm and the stress drop to be 36 bars.The 1918 earthquake appears to be a crustal intraplate event occurring in the lithosphere of the America plate, resulting from the complicated interaction of the Explorer, Juan de Fuca, and America plates. The preferred epicenter, depth, focal mechanism, and stress drop for the 1957 earthquake are consistent with the left-lateral motion between the Juan de Fuca and Explorer plates along the subducted extension of the Nootka fault zone. This earthquake is identical, within uncertainties, to events occurring in 1972 and 1986. We believe that these three earthquakes provide the best definition to date of both the position of the subducting portion of the Nootka fault zone west of Vancouver Island and the direction of relative motion along this fault.
Microearthquake location: A nonlinear approach that makes use of a simplex stepping procedure
Authors: Prugger Arnfinn F. , Gendzwill Don J. 
Published: July 2021

AbstractWe present an earthquake location scheme that uses the simplex algorithm in the solution. This method of direct iteration is conceptually simple, does not require derivative calculations, and avoids matrix inversions. The algorithm can be programmed on a small computer and its performance compares favorably with other methods of earthquake location. The method can be used for any velocity structure for which source to geophone times can be calculated. We use a horizontally layered velocity model, and consider both critically and noncritically refracted rays. It is easy to incorporate any time residual misfit norm into the location calculation. We generally use the L1 or L2 (least-squares) norm. The routine we present is used in two different microseismic monitoring systems at two potash mines in Saskatchewan, Canada.
Maximum-likelihood event magnitude estimation with bootstrapping for uncertainty estimation
Authors: McLaughlin K. L. 
Published: July 2021

AbstractThe bootstrap procedure of Efron may be used with maximum-likelihood magnitude estimation to estimate the standard deviation of the event magnitude and the distribution standard deviation. The procedure resamples the observations randomly with replacement. The event magnitude, m, and station magnitude distribution, σ, are then estimated for each random sampling of the observations. This generates a sequence of event magnitude estimations that are used to estimate the event magnitude standard error, σm, and the uncertainty in the distribution, σσ.Maximum-likelihood mb event magnitudes with uncertainties are provided for events at NTS, Amchitka, Tuamotu, Novaya Zemlya, and Eastern Kazakh. These magnitudes based on WWSSN film chip readings illustrate the importance of nondetection for events with magnitudes below mb &lt; 5 and of clipping for events with magnitudes above mb &gt; 6.5. The uncertainties in the event magnitudes are found to be close to the uncertainty in the mean of the observed signals. The introduction of the maximum-likelihood procedure does not significantly improve the precision of the event magnitude estimate, and furthermore it may actually increase the estimated uncertainty with introduction of censoring information. However, the maximum-likelihood bootstrap estimate is a more accurate estimate of the total uncertainty in the event magnitude.
Frequency and size of quaternary surface ruptures of the pitaycachi fault, northeastern Sonora, Mexico
Authors: Bull William B. , Pearthree Philip A. 
Published: July 2021

AbstractMovements along the Pitaycachi fault since the Miocene juxtaposed different alluvial units and created 2- to 45-m-high fault scarps downslope from a pedimented mountain front prior to 1887. In 1887, a major earthquake formed a 75-km-long, 12- to 4-m-high scarp along the trace of prehistoric surface ruptures.Diverse evidence from many study sites indicates that about 200,000 yr elapsed between the prior (youngest Pleistocene) event and the 1887 surface rupture. Cumulative displacements of Pliocene(?) to mid-Pleistocene alluvial fans and stream terraces decrease with decreasing age. The trace of the prior rupture was largely buried by sheets of late Pleistocene and Holocene piedmont alluvium. Late Pleistocene soils are offset about the same amount as the height of the 1887 scarp. Valleys that are as much as 40 m deep and 0.5 to 0.9 km wide have been eroded since the prior event; they contain multiple late Pleistocene and Holocene stream terraces that were not faulted until 1887. Pre-1887 alluvial fault scarps were degraded to 2° to 9° slopes before the 1887 event, even in resistant materials such as clay-rich soil horizons with unweathered rhyolite cobbles and calcrete. Scarp height-maximum slope regressions and diffusion-equation analyses for reconstructed pre-1887 scarp profiles indicate that the prior event occurred more than 100,000 yr ago. Acceleration of scarp degradation rates during the Holocene, and/or relatively resistant materials exposed in the scarps, would increase the age estimates to 200,000 yr or more.Very long recurrence intervals are the characteristic style of movement on the Pitaycachi fault. At one site, six ages of diverse valley fills were inset into pedimented granodiorite upslope from the fault between the prior and 1887 events. Only 3 m of relief remained before the 1887 rupture increased the scarp height from 3 to 6 m. Some hillslopes have triangular talus facets of carbonatecemented colluvium that resulted from infrequent fault movements and intervening periods of erosion. Smooth hillsides of resistant volcanic rocks between the facets show that virtually all of the prior surface-rupture event scarps had been removed by prolonged slope degradation.
Earthquake locations in the western Hellenic arc relative to the plate boundary
Authors: Papadopoulos T. , Wyss Max , Schmerge David L. 
Published: July 2021

AbstractFour vertical-component seismograph stations were operated in western Crete, southeastern Peloponnesus, the island of Milos, and south of Corinth on Mount Didimon from 1981 to 1984. Combining arrival times from this network, the Greek National Network, and VOLNET, we relocated hypocenters within Greece and the surrounding area. The difference between the relocations and the locations published in the National Observatory of Athens Bulletin in most instances were minor, except for earthquakes located in the vicinity of the western Hellenic arc. In this area, we found that epicenters thought to lie south of the plate boundary, within the African plate, relocated an average of approximately 60 km to the N30°E, which places them at or north of the plate boundary. We suggest that this difference is a minimum estimate of the location error and the true locations may lie still further to the NNE. We propose that anomalously slow seismic velocities in the Aegean back-arc upper mantle cause travel-time delays to the seismograph stations located to the NE of the source volumes, resulting in location errors in a direction away from these stations. Extrapolating from our observations to other segments of the Hellenic plate boundary and to periods not covered by our operation, we hypothesize that most or all earthquakes thought to have originated on the African plate, within about 100 km of the Hellenic arc, were actually located at the plate boundary or on the Aegean plate.
CodaQbefore the 1983 Hawaii (MS= 6.6) earthquake
Authors: Huang Zhong-Xian , Wyss Max 
Published: July 2021

AbstractCoda Q values were derived for more than 300 microearthquakes that occurred in a 6-yr period before the 16 November 1983 Kaoiki, Hawaii, earthquake (MS = 6.6). The sources were located within a 14 × 16 km rectangular region surrounding the main shock epicenter, and most of them occurred at depths between 5 and 10 km. Digital recordings from three stations at epicentral distances ranging from 0 to 18 km were used. Coda Q was calculated from the amplitude decay rate of the S-wave coda in nine frequency bands from 4.5 to 27 Hz. The average Q of the NW part of the studied area is about 15 per cent higher than that of the SE part. These two subregions also showed differences in seismicity, b value, and microearthquake source mechanisms. In the high-Q volume, the b value was 1.0, and the rate of earthquakes per unit volume was about 50 per cent of the rate in the low-Q volume where b = 1.3. One interpretation of these observations is that more extensive faulting in the SE Kaoiki fault zone leads to lower Q, higher b value, and a higher seismicity rate. During the 5 to 6 yr before the mainshock, the 1-yr average Q values were stable. No significant Q change could be identified as a precursor to the main shock.
Spectral discrimination between NTS explosions and Western United States earthquakes at regional distances
Authors: Taylor Steven R. , Sherman Nevin W. , Denny Marvin D. 
Published: July 2021

AbstractSpectral ratio disciminants are applied to 72 Western United States earthquakes and 64 NTS explosions recorded at four broadband seismic stations surrounding NTS. The ratio of the energy in the 1- to 2- and 6- to 8-Hz bands for Pn, Pg, and Lg is calculated and a simple distance correction applied to the data. The spectral ratio appears to have potential as a disciminant at relatively small magnitudes (3.0 &lt; mb &lt; 4.5) and single station misclassification probabilities for detected phases range from 4 to 33 per cent, with Lg showing the best performance followed by Pg and Pn. Below mb 4.5 to 5.0, the earthquakes are observed to have more high-frequency energy than the explosions for all three phases. This observation may be due to actual source differences or to depth-dependent effects of attenuation on the shallow explosions and deeper earthquakes. At higher magnitudes, the two populations merge and discrimination is poor. Overburied explosions are characterized by the existence of more high-frequency energy than those at standard containment depths and are often misclassified. The Brune dislocation source model is shown to satisfactorily fit the earthquake spectral ratios plotted as a function of mb for reasonable stress drops. However, the Mueller-Murphy explosion source model has problems predicting the decrease in the explosion spectral ratio observed at higher magnitudes (mb &gt; 4.5 to 5.0). This may be due to uncertainties in the apparent source-time function for explosions. These complications may be due to changes in the dynamic response of the material in the near-source region as a function of overburden pressure, effects of secondary sources, or to variations in regional phase excitation with depth.
Two types of reservoir-induced seismicity
Authors: Simpson D.W. , Leith W.S. , Scholz C.H. 
Published: July 2021

AbstractThe temporal distribution of induced seismicity following the filling of large reservoirs shows two types of response. At some reservoirs, seismicity begins almost immediately following the first filling of the reservoir. At others, pronounced increases in seismicity are not observed until a number of seasonal filling cycles have passed. These differences in response may correspond to two fundamental mechanisms by which a reservoir can modify the strength of the crust—one related to rapid increases in elastic stress due to the load of the reservoir and the other to the more gradual diffusion of water from the reservoir to hypocentral depths. Decreased strength can arise from changes in either elastic stress (decreased normal stress or increased shear stress) or from decreased effective normal stress due to increased pore pressure. Pore pressure at hypocentral depths can rise rapidly, from a coupled elastic response due to compaction of pore space, or more slowly, with the diffusion of water from the surface.
Inverting measurements of surface slip on the Superstition Hills fault
Authors: Boatwright John , Budding Karin E. , Sharp Robert V. 
Published: July 2021

AbstractWe derive and test a set of inversions of surface-slip measurements based on the empirical relation u(t) = uf/(1 + T/t)c proposed by Sharp and Saxton (1989) to estimate the final slip uf, the power-law exponent c, and the power-law duration T. At short times, Sharp's relation behaves like the simple power law, u(t) ∼ u1tc, where u1 is the initial slip, that is, the slip at 1 day after the earthquake. At long times, the slip approaches the final slip asymptotically. The inversions are designed in part to exploit the accuracy of measurements of differential slip; that is, measurements of surface slip which are made relative to a set of nails or stakes emplaced after the earthquake. We apply the inversions to slip measurements made at 53 sites along the Superstition Hills fault for the 11 months following the M = 6.2 and 6.6 earthquakes of 24 November 1987. In general, estimates of the initial slip and the power law exponent are well resolved, while estimates of the power-law durations and the final slip are less well resolved because the durations of the surface slip measurements are often less than the derived power-law durations. The slip on the three fault strands is a relatively smooth function of position; the initial slip and final slip are well correlated. The time dependence of surface slip at the 53 sites is roughly similar along the entire fault, where the power-law exponents are distributed as c = 0.14 ± 0.04 and the power-law durations range from 100 &lt; T &lt; 1000 days.
High-frequencyPnattenuation in the Canadian shield
Authors: Chun Kin-Yip , Kokoski Richard J. , West Gordon F. 
Published: July 2021

AbstractFrequency-dependent spatial attenuation of Pn waves, incorporating the combined effects of geometrical spreading and anelastic dissipation, is investigated in eastern Canada between 3 and 15 Hz. Measurement of this total attenuation, instead of the two separate effects, circumvents the usual need for making a priori assumptions regarding the Pn geometrical spreading rate. The data consist of 77 Pn spectra, all amplitude-normalized using a set of previously measured spectral ratios of eastern Canadian earthquake sources. The normalization procedure eliminates the need for explicit source spectral assumptions, another common source of error in Pn attenuation measurements. An unconventional technique is introduced to account for differences in observed Pn spectra, which arise from geological site effects and instrument response error, both of which are frequency-dependent phenomena. We conclude that, at each frequency, the Pn amplitude falls off with distance according to: Δ−n, where Δ is epicentral distance. The exponent n is weakly frequency-dependent and takes the form: 2.2 + 0.02f. A unique interpretation of the behavior of the Pn spectral amplitude decay is unattainable, owing to the difficulty in separating the effects due to anelastic dissipation and the velocity structure in the uppermost mantle. It is interesting to note, however, that the spatial decay of pure elastic head waves follows the classical Δ−1/2L−3/2 relation, where L is the distance the waves travel in the mantle refractor. For the distance range of our interest (260-1087 km), this amounts to Δ−2.2. This indicates that towards low frequencies our n approaches a value which is consistent with the spatial decay rate expected of pure elastic head waves.
Attenuation of refracted seismic waves in young oceanic crust
Authors: Lewis B. T. R. , Jung H. 
Published: July 2021

AbstractIt is commonly observed in seismic refraction experiments over young oceanic crust that refracted energy is concentrated in the 10 to 15 Hz band, even though the source may have far greater bandwidth. We apply spectral ratio methods to data from a midwater hydrophone array towed 10 km from the Juan de Fuca ridge and confirm that the impulse response of the crust to refracted energy has a peak near 10 Hz. This peak appears to result from a combination of two factors that produce attenuation. One is related to the large velocity gradient in the upper crust caused by crack closure with increasing depth. The other is related to anelastic attenuation, which is probably also related to cracks and voids in the upper crust. At low frequencies (wavelengths greater than or equal to the thickness of the high gradient zone), it is shown that attenuation is dominated by the reflectivity of the upper crust. At high frequencies attenuation is dominated by anelastic effects associated with upper crust Q's of between 10 and 50. The wave propagation is dispersive, causing observable phase shifts in the response function, and Q may be frequency dependent. This model of the propagation explains why refraction data over young oceanic crust have energy concentrated near 10 Hz.
Recursive deconvolution filters for seismograph systems
Authors: Ferber R.-G. 
Published: July 2021

Abstract
A time-domain solution of the deconvolution problem for digital recordings from seismograph systems is given. Compensation for the signal distortion caused by the seismograph can be done by numerical data processing of the recorded seismograms using recursive filters which are designed from the analog transfer function using the bilinear z-transform. An application of the method is worked out for the seismograph system of the Central Seismological Observatory Gräfenberg, F. R. Germany.