197 research outputs found
Estimation of <i>Vs</i> profile using its natural frequency and Rayleigh-wave dispersion characteristics
International audienceThe evaluation of the natural frequency of random Vs profiles before analyzing the fundamental Rayleigh-wave dispersion characteristics is proposed in this paper. The inclusion of this parameter optimizes the effectiveness of random inverse searching to estimate Vs profiles. To demonstrate this method, a numerical test was performed using the "experimental" Rayleigh-wave dispersion curve obtained for a fictitious TEST site
Laugh syncope as a rare sub-type of the situational syncopes: a case report
<p>Abstract</p> <p>Introduction</p> <p>Laughter is a good medicine; it enhances cardiovascular health and the immune system. What happens, however, if a person laughs too much or the laughter becomes out of control? Laughter-induced syncope is rare and likely goes unrecognized by many health care providers. It is thought to be another form of Valsalva-induced syncope.</p> <p>Case presentation</p> <p>We report the case of a 56-year-old, moderately obese (body mass index of 35) man with a past medical history of sleep apnea, hypertension and hyperlipidemia who suffered from syncope secondary to intense laughter. The patient also had a history of syncope in the distant past when he collapsed on the floor for several seconds. Treadmill stress testing after the incident revealed no arrhythmia or ischemic disease, although he complained of dizziness after the test and a sudden drop in blood pressure was noted.</p> <p>Conclusion</p> <p>Laughter-induced or gelastic syncope is extremely rare. It is thought to be a sub-type of the situational syncopes.</p
Interpretation of microtremor 2D array data using Rayleigh and Love waves: the case study of Bevagna (central Italy)
In the last decades, geophysicists and seismologists have focused their attention on the inversion of
empirical surface-waves’ dispersion curves from microtremor measurements for estimating the Swaves
velocity structure at a site. This procedure allows a fast and convenient investigation without
strong active sources, which are difficult to deploy especially in urban areas.
In this study we report on a 2D seismic noise array experiment carried out at Bevagna (Central
Italy) near the station BVG of the Italian Accelerometric Network (RAN). The site was investigated
within the DPC-INGV S4 Project (2007-2009). The Rayleigh- and Love- waves dispersion
characteristics were estimated using different methods. The inversion of the dispersion curves was
then performed independently, obtaining two estimations for the S-waves velocity profiles. The
results of cross-hole logging near the seismic station are used for a comparison.
The shear waves velocity profiles estimated by microtremor analyses range up to 150m depth. The
two independent procedures provide consistent shear waves velocity profiles for the shallow part of
the model (20-30 m in depth) in agreement with the results of the cross-hole logging. Some
problems arise between 30 and 40 m in depth in the profile estimated by surface waves. In this
range cross-hole logging evidences an inversion of S-waves velocity. Although the cross-hole
logging stops at 40 m of depth, we are confident about the results provided by the Rayleigh-waves
analysis below 40-50 m. This case study suggests that greater efforts should be devoted to exploit
the potential of a coupled analysis of Rayleigh and Love waves from microtremor array
measurements
Microtremor measurements interpretations at the BVG station of the Italian accelerometric network
In the last decades, researchers focused their attention on using inverse analysis of empirical surface‐waves
dispersion curves from microtremor measurements since it allows to keep the cost of investigation
relatively low and to avoid the use of active sources that might be prohibitive in urban areas.
In this study we reports the results and interpretations of the passive measurements carried out at a test
site in Bevagna (Italy) near the BVG station of the Italian Accelerometric Network (RAN) within the
framework of the DPC‐INGV S4 Project (2007‐2009). Using two independent approaches, Rayleigh and Love
wave dispersion characteristics were reproduced through two different inversion methods. At this site a
cross‐hole test made nearby the seismic station offers the opportunity to compare the subsoil velocity
profiles derived by seismic noise array data with independent geophysical information.
The results obtained from the separated Love waves and Rayleigh wave inversions analyses showed that
the two procedure provide consistent shear wave velocity profiles for the shallow part of the model in good
agreement with the results of the nearby cross‐hole test.
This case history shows the capabilities of surface wave analyses from passive source to adequately retrieve
the S‐wave subsoil structure and suggests that more efforts should be devoted in exploiting the potential of
coupled analysis of Rayleigh and Love waves from microtremor array measurements for site
characterization
Analysis of IgE turnover in non-sensitized and sensitized rats.
BACKGROUND: Although the levels of immunoglobulin E (IgE) in the circulating blood are often elevated in patients with allergic diseases, such levels cannot always be considered as pathognomonic signs of allergy. The induction of allergic reactions in the tissue was inferred to be related to the amount of IgE passing through the vascular wall. AIMS: We attempted to clarify which compartment, the intravascular or extravascular, plays an important role in the regulation of the turnover of rat IgE. METHODS: The level of DNP-specific rat IgE in the serum was estimated by IgE-capture enzyme-linked immunosorbent assay, and the turnover of IgE was analyzed from its pharmacokinetic parameters. RESULTS: The transfer rate constants from the central to tissue compartment (Kct) were larger than those from the tissue to central compartment (Ktc) irrespective of the sensitized state. The value of the distribution volume of the tissue compartment (Vt) was larger than that of the distribution volume of the central compartment (Vc) irrespective of the sensitized state. CONCLUSIONS: These Findings suggest that the short half-life of rat IgE in the circulation could be attributable to the distribution of IgE from the intravascular to the extravascular compartment
Reproductive Isolation and Ecological Niche Partition among Larvae of the Morphologically Cryptic Sister Species Chironomus riparius and C. piger
Background One of the central issues in ecology is the question what allows sympatric occurrence of closely related species in the same general area? The non-biting midges Chironomus riparius and C. piger, interbreeding in the laboratory, have been shown to coexist frequently despite of their close relatedness, similar ecology and high morphological similarity. Methodology/Principal Findings In order to investigate factors shaping niche partitioning of these cryptic sister species, we explored the actual degree of reproductive isolation in the field. Congruent results from nuclear microsatellite and mitochondrial haplotype analyses indicated complete absence of interspecific gene-flow. Autocorrelation analysis showed a non-random spatial distribution of the two species. Though not dispersal limited at the scale of the study area, the sister species occurred less often than expected at the same site, indicating past or present competition. Correlation and multiple regression analyses suggested the repartition of the available habitat along water chemistry gradients (nitrite, conductivity, CaCO3), ultimately governed by differences in summer precipitation regime. Conclusions We show that these morphologically cryptic sister species partition their niches due to a certain degree of ecological distinctness and total reproductive isolation in the field. The coexistence of these species provides a suitable model system for the investigation of factors shaping the distribution of closely related, cryptic species
Fabrication of Functionalized Double-Lamellar Multifunctional Envelope-Type Nanodevices Using a Microfluidic Chip with a Chaotic Mixer Array
Multifunctional envelope-type nanodevices (MENDs) are very promising non-viral gene delivery vectors because they are biocompatible and enable programmed packaging of various functional elements into an individual nanostructured liposome. Conventionally MENDs have been fabricated by complicated, labor-intensive, time-consuming bulk batch methods. To avoid these problems in MEND fabrication, we adopted a microfluidic chip with a chaotic mixer array on the floor of its reaction channel. The array was composed of 69 cycles of the staggered chaotic mixer with bas-relief structures. Although the reaction channel had very large Péclet numbers (>105) favorable for laminar flows, its chaotic mixer array led to very small mixing lengths (<1.5 cm) and that allowed homogeneous mixing of MEND precursors in a short time. Using the microfluidic chip, we fabricated a double-lamellar MEND (D-MEND) composed of a condensed plasmid DNA core and a lipid bilayer membrane envelope as well as the D-MEND modified with trans-membrane peptide octaarginine. Our lab-on-a-chip approach was much simpler, faster, and more convenient for fabricating the MENDs, as compared with the conventional bulk batch approaches. Further, the physical properties of the on-chip-fabricated MENDs were comparable to or better than those of the bulk batch-fabricated MENDs. Our fabrication strategy using microfluidic chips with short mixing length reaction channels may provide practical ways for constructing more elegant liposome-based non-viral vectors that can effectively penetrate all membranes in cells and lead to high gene transfection efficiency
Rank abundance relations in evolutionary dynamics of random replicators
We present a non-equilibrium statistical mechanics description of rank
abundance relations (RAR) in random community models of ecology. Specifically,
we study a multi-species replicator system with quenched random interaction
matrices. We here consider symmetric interactions as well as asymmetric and
anti-symmetric cases. RARs are obtained analytically via a generating
functional analysis, describing fixed-point states of the system in terms of a
small set of order parameters, and in dependence on the symmetry or otherwise
of interactions and on the productivity of the community. Our work is an
extension of Tokita [Phys. Rev. Lett. {\bf 93} 178102 (2004)], where the case
of symmetric interactions was considered within an equilibrium setup. The
species abundance distribution in our model come out as truncated normal
distributions or transformations thereof and, in some case, are similar to
left-skewed distributions observed in ecology. We also discuss the interaction
structure of the resulting food-web of stable species at stationarity, cases of
heterogeneous co-operation pressures as well as effects of finite system size
and of higher-order interactions.Comment: 12 pages, 14 figures; text amended, minor corrections/modifications
to figure
Pre-incubation of porcine semen reduces the incidence of polyspermy on embryos derived from low quality oocytes
Universal Ecological Patterns in College Basketball Communities
The rank abundance of common and rare species within ecological communities is remarkably consistent from the tropics to the tundra. This invariant patterning provides one of ecology's most enduring and unified tenets: most species rare and a few very common. Increasingly, attention is focused upon elucidating biological mechanisms that explain these species abundance distributions (SADs), but these evaluations remain controversial. We show that college basketball wins generate SADs just like those observed in ecological communities. Whereas college basketball wins are structured by competitive interactions, the result produces a SAD pattern indistinguishable from random wins. We also show that species abundance data for tropical trees exhibits a significant-digit pattern consistent with data derived from complex structuring forces. These results cast doubt upon the ability of SAD analysis to resolve ecological mechanism, and their patterning may reflect statistical artifact as much as biological processes
- …