A mathematical view of water table fluctuations in a shallow aquifer in Brazil

Detailed monitoring of the groundwater table can provide important data about both short- and long-term aquifer processes, including information useful for estimating recharge and facilitating groundwater modeling and remediation efforts. In this paper, we presents results of 4 years (2002 to 2005) of monitoring groundwater water levels in the Rio Claro Aquifer using observation wells drilled at the Rio Claro campus of São Paulo State University in Brazil. The data were used to follow natural periodic fluctuations in the water table, specifically those resulting from earth tides and seasonal recharge cycles. Statistical analyses included methods of time-series analysis using Fourier analysis, cross-correlation, and R/S analysis. Relationships could be established between rainfall and well recovery, as well as the persistence and degree of autocorrelation of the water table variations. We further used numerical solutions of the Richards equation to obtain estimates of the recharge rate and seasonable groundwater fluctuations. Seasonable soil moisture transit times through the vadose zone obtained with the numerical solution were very close to those obtained with the cross-correlation analysis. We also employed a little-used deep drainage boundary condition to obtain estimates of seasonable water table fluctuations, which were found to be consistent with observed transient groundwater levels during the period of study.

Scherverhalten kolloidaler Lagenphasen in Rohrströmungen

Kolloidale Suspensionen aus identischen kugelförmigen, geladenen Partikeln in wässrigen Medien stellen ein ideales Modellsystem zur Untersuchung des Gleichgewichtsverhaltens, aber auch des Nicht-Gleichgewichtsverhaltens Weicher Materie dar. So bilden derartige Systeme bei hinreichend starker und langreichweitiger elektrostatischer Repulsion fluid und kristallin geordnete Strukturen aus, die wegen der weitreichenden Analogie zu atomar kondensierter Materie als kolloidale Fluide und Kristalle bezeichnet werden. Von großem Vorteil ist dabei die Möglichkeit zur kontrollierten Einstellung der Wechselwirkung und die gute optische Zugänglichkeit für Mikroskopie und Lichtstreuung sowie die Weichheit der Materialien, aufgrund derer sich auch Zustände fernab des mechanischen Gleichgewichts gezielt präparieren lassen. Themenstellung der vorliegenden Arbeit ist die Untersuchung des Phasenverhaltens und der Fließmechanismen kolloidaler Kristalle in einer Rohrströmung. Im ersten Teil der Arbeit wird gezeigt, dass beim Fluss durch eine zylindrische Röhre Mehrphasenkoexistenz auftritt, wobei ein polykristalliner Kern von einer isotropen Scherschmelze umgeben ist. Zusätzlich treten an der Grenze zwischen diesen Phasen und an der Rohrwand Phasen hexagonal geordneter übereinander hinweggleitender Lagen auf. Der Vergleich zwischen auf der Basis der Navier-Stokes-Gleichung theoretisch berechneten und gemessenen Geschwindigkeitsprofilen zeigt, dass jede dieser Phasen für sich Newtonsches Fließverhalten aufweist. Die Gesamtviskosität ist hingegen durch die mit dem Durchsatz veränderliche Phasenzusammensetzung Nicht-Newtonsch. Damit gelang es, die erstmalig von Würth beschriebene Scherverdünnung auf eine Veränderung der Phasenzusammensetzung zurückzuführen. Im zweiten Teil der Arbeit wurde erstmals das Fließverhalten der Lagenphasen mittels Lichtstreuung und Korrelationsanalyse untersucht. Dafür wurde ein im Prinzip einfacher, aber leistungsstarker Aufbau realisiert, der es erlaubt, die zeitliche Veränderung der Bragg-Reflexe der Lagenphase in radialer und azimutaler Richtung zu verfolgen und mittels Fourieranalyse zu analysieren. In Abhängigkeit vom Durchsatz geht die zunächst rastend gleitende Lagenphase in eine frei gleitende Lagenphase über, wobei charakteristische Veränderungen der Spektren sowie der Korrelationsfunktionen auftreten, die detailliert diskutiert werden. Der Übergang im Gleitmechanismus ist mit einem Verlust der Autokorrelation der Rotationskomponente der periodischen Intra-Lagenverzerrung verbunden, während die Kompressionskomponente erhalten bleibt. Bei hohen Durchflüssen lassen die Reflexbewegungen auf das Auftreten einer Eigenschwingung der frei gleitenden Lagen schließen. Diese Schwingung lässt sich als Rotationsbewegung, gekoppelt mit einer transversalen Auslenkung in Vortexrichtung, beschreiben. Die Ergebnisse erlauben eine detaillierte Diskussion von verschiedenen Modellvorstellungen anderer Autoren.

Realisierung der IceCube MonteCarlo-Produktion im WLCG und Untersuchung von Auswirkungen meteorologischer Parameter auf die Erzeugung atmosphärischer Myonen

Das am Südpol gelegene Neutrinoteleskop IceCube detektiert hochenergetische Neutrinos über die schwache Wechselwirkung geladener und neutraler Ströme. Die Analyse basiert auf einem Vergleich mit Monte-Carlo-Simulationen, deren Produktion global koordiniert wird. In Mainz ist es erstmalig gelungen, Simulationen innerhalb der Architektur des Worldwide LHC Computing Grid (WLCG) zu realisieren, was die Möglichkeit eröffnet, Monte-Carlo-Berechnungen auch auf andere deutsche Rechnerfarmen (CEs) mit IceCube-Berechtigung zu verteilen. Atmosphärische Myonen werden mit einer Rate von über 1000 Ereignissen pro Sekunde aufgezeichnet. Eine korrekte Interpretation dieses dominanten Signals, welches um einen Faktor von 10^6 reduziert werden muss um das eigentliche Neutrinosignal zu extrahieren, ist deswegen von großer Bedeutung. Eigene Simulationen mit der Software-Umgebung CORSIKA wurden durchgeführt um die von Energie und Einfallswinkel abhängige Entstehungshöhe atmosphärischer Myonen zu bestimmen. IceCube Myonraten wurden mit Wetterdaten des European Centre for Medium-Range Weather Forcasts (ECMWF) verglichen und Korrelationen zwischen jahreszeitlichen sowie kurzzeitigen Schwankungen der Atmosphärentemperatur und Myonraten konnten nachgewiesen werden. Zudem wurde eine Suche nach periodischen Effekten in der Atmosphäre, verursacht durch z.B. meteorologische Schwerewellen, mit Hilfe einer Fourieranalyse anhand der IceCube-Daten durchgeführt. Bislang konnte kein signifikanter Nachweis zur Existenz von Schwerewellen am Südpol erbracht werden.

Prediction and measurement of forced response of a composite blade undergoing nonlinear vibration

The main objective of this project is to experimentally demonstrate geometrical nonlinear phenomena due to large displacements during resonant vibration of composite materials and to explain the problem associated with fatigue prediction at resonant conditions. Three different composite blades to be tested were designed and manufactured, being their difference in the composite layup (i.e. unidirectional, cross-ply, and angle-ply layups). Manual envelope bagging technique is explained as applied to the actual manufacturing of the components; problems encountered and their solutions are detailed. Forced response tests of the first flexural, first torsional, and second flexural modes were performed by means of a uniquely contactless excitation system which induced vibration by using a pulsed airflow. Vibration intensity was acquired by means of Polytec LDV system. The first flexural mode is found to be completely linear irrespective of the vibration amplitude. The first torsional mode exhibits a general nonlinear softening behaviour which is interestingly coupled with a hardening behaviour for the unidirectional layup. The second flexural mode has a hardening nonlinear behaviour for either the unidirectional and angle-ply blade, whereas it is slightly softening for the cross-ply layup. By using the same equipment as that used for forced response analyses, free decay tests were performed at different airflow intensities. Discrete Fourier Trasform over the entire decay and Sliding DFT were computed so as to visualise the presence of nonlinear superharmonics in the decay signal and when they were damped out from the vibration over the decay time. Linear modes exhibit an exponential decay, while nonlinearities are associated with a dry-friction damping phenomenon which tends to increase with increasing amplitude. Damping ratio is derived from logarithmic decrement for the exponential branch of the decay.

Altered cardiovascular rhythmicity in children with white coat and ambulatory hypertension

Adults with ambulatory hypertension or white coat hypertension (WCH) display abnormal cardiovascular rhythms. We studied cardiovascular rhythms by Fourier analysis of 24-h ambulatory blood pressure (BP) measurement profiles in 129 hypertensive children, 54 children with WCH, and 146 age-, height-, and gender-matched healthy subjects. The day/night mean arterial pressure ratio was lower in hypertensive and patients with WCH compared with controls (1.13 versus 1.16 versus 1.21, respectively; p < 0.0001). Eighty-five percent of controls were dippers compared with 74% of WCH (n.s.) and 64% of patients with ambulatory hypertension (p < 0.0001). The prevalence of 24-h rhythms was similar among the groups, but prevalence of 12-h BP rhythms was increased in hypertensive (67%) and WCH (72%) compared with controls (51%, p < 0.0001). The amplitudes of the 24-, 8-, and 6-h BP rhythms were reduced in hypertensive and WCH compared with controls (p < 0.05). Hypertensive and patients with WCH displayed delayed 24-, 12-, 8-, 6-h acrophases in comparison with controls (p < 0.05). In conclusion, hypertensive children exhibit abnormal cardiovascular rhythmicity compared with controls, especially a higher prevalence of nondipping compared with normotensive children. Abnormalities in patients with WCH are intermediate between healthy children and patients with ambulatory hypertension.

Parallel vector processing of multidimensional orthogonal transforms for digital signal processing applications

The performance of the parallel vector implementation of the one- and two-dimensional orthogonal transforms is evaluated. The orthogonal transforms are computed using actual or modified fast Fourier transform (FFT) kernels. The factors considered in comparing the speed-up of these vectorized digital signal processing algorithms are discussed and it is shown that the traditional way of comparing th execution speed of digital signal processing algorithms by the ratios of the number of multiplications and additions is no longer effective for vector implementation; the structure of the algorithm must also be considered as a factor when comparing the execution speed of vectorized digital signal processing algorithms. Simulation results on the Cray X/MP with the following orthogonal transforms are presented: discrete Fourier transform (DFT), discrete cosine transform (DCT), discrete sine transform (DST), discrete Hartley transform (DHT), discrete Walsh transform (DWHT), and discrete Hadamard transform (DHDT). A comparison between the DHT and the fast Hartley transform is also included.(34 refs)

Autonomic cardiovascular regulation in obesity

Obese persons suffer from an increased mortality risk supposedly due to cardiovascular disorders related to either continuously lowered parasympathetic or altered sympathetic activation. Our cross-sectional correlation study establishes the relationship between obesity and autonomic regulation as well as salivary cortisol levels. Three patient cohorts were sampled, covering ranges of body mass index (BMI) of 27-32 (n=17), 33-39 (n=13) and above 40 kg/m(2)(n=12), and stratified for age, sex and menopausal status. Autonomic cardiovascular regulation was assessed by use of heart rate variability and continuous blood pressure recordings. Spectral analytical calculation (discrete Fourier transformation) yields indices of sympathetic and parasympathetic activation and baroreflex sensitivity. Morning salivary cortisol was concurrently collected. Contrary to expectation, BMI and waist/hip ratio (WHR) were inversely correlated with sympathetic activity. This was true for resting conditions (r=-0.48, P<0.001; r=-0.33, P<0.05 for BMI and WHR respectively) and for mental challenge (r=-0.42, P<0.01 for BMI). Resting baroreflex sensitivity was strongly related to the degree of obesity at rest (BMI: r=-0.35, P<0.05) and for mental challenge (r=-0.53, P<0.001). Salivary cortisol correlated significantly with waist circumference (r=-0.34, P=0.05). With increasing weight, no overstimulation was found but a depression in sympathetic and parasympathetic activity together with a significant reduction in baroreflex functioning and in salivary cortisol levels.

SOLUTE-DERIVED THERMAL STABILITY OF NANOCRYSTALLINE ALUMINUM AND PROCESSING FACTOR INFLUENCE ON THE FORMATION OF AL6MN QUASICRYSTALS IN MELT-SPINNING

Thermal stability of nanograined metals can be difficult to attain due to the large driving force for grain growth that arises from the significant boundary area constituted by the nanostructure. Kinetic approaches for stabilization of the nanostructure effective at low homologous temperatures often fail at higher homologous temperatures. Thermodynamic approaches for thermal stabilization may offer higher temperature stability. In this research, modest alloying of aluminum with solute (1 at.% Sc, Yb, or Sr) was examined as a means to thermodynamically stabilize a bulk nanostructure at elevated temperatures. After using melt-spinning and ball-milling to create an extended solid-solution and nanostructure with average grain size on the order of 30-45 nm, 1 h annealing treatments at 673 K (0.72 Tm) , 773 K (0.83 Tm) , and 873 K (0.94 Tm) were applied. The alloys remain nanocrystalline (<100 nm) as measured by Warren-Averbach Fourier analysis of x-ray diffraction peaks and direct observation of TEM dark field micrographs, with the efficacy of stabilization: Sr>Yb>Sc. Disappearance of intermetallic phases in the Sr and Yb alloys in the x-ray diffraction spectra are observed to occur coincident with the stabilization after annealing, suggesting that precipitates dissolve and the boundaries are enriched with solute. Melt-spinning has also been shown to be an effective process to produce a class of ordered, but non-periodic crystals called quasicrystals. However, many of the factors related to the creation of the quasicrystals through melt-spinning are not optimized for specific chemistries and alloy systems. In a related but separate aspect of this research, meltspinning was utilized to create metastable quasicrystalline Al6Mn in an α-Al matrix through rapid solidification of Al-8Mn (by mol) and Al-10Mn (by mol) alloys. Wheel speed of the melt-spinning wheel and orifice diameter of the tube reservoir were varied to determine their effect on the resulting volume proportions of the resultant phases using integrated areas of collected x-ray diffraction spectra. The data were then used to extrapolate parameters for the Al-10Mn alloy which consistently produced Al6Mn quasicrystal with almost complete suppression of the equilibrium Al6Mn orthorhombic phase.

The rotation state of 67P/Churyumov-Gerasimenko from approach observations with the OSIRIS cameras on Rosetta

Aims. Approach observations with the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) experiment onboard Rosetta are used to determine the rotation period, the direction of the spin axis, and the state of rotation of comet 67P’s nucleus. Methods. Photometric time series of 67P have been acquired by OSIRIS since the post wake-up commissioning of the payload in March 2014. Fourier analysis and convex shape inversion methods have been applied to the Rosetta data as well to the available ground-based observations. Results. Evidence is found that the rotation rate of 67P has significantly changed near the time of its 2009 perihelion passage, probably due to sublimation-induced torque. We find that the sidereal rotation periods P1 = 12.76129 ± 0.00005 h and P2 = 12.4043 ± 0.0007 h for the apparitions before and after the 2009 perihelion, respectively, provide the best fit to the observations. No signs of multiple periodicity are found in the light curves down to the noise level, which implies that the comet is presently in a simple rotation state around its axis of largest moment of inertia. We derive a prograde rotation model with spin vector J2000 ecliptic coordinates λ = 65° ± 15°, β = + 59° ± 15°, corresponding to equatorial coordinates RA = 22°, Dec = + 76°. However, we find that the mirror solution, also prograde, at λ = 275° ± 15°, β = + 50° ± 15° (or RA = 274°, Dec = + 27°), is also possible at the same confidence level, due to the intrinsic ambiguity of the photometric problem for observations performed close to the ecliptic plane.

The impact of host immunity on oscillating rates of syphilis when gender and race are considered

The rates of syphilis in the United States have increased since the all time low in 2000. In 2003, the rates of syphilis in the United States were 2.5 cases per 100,000. There were 178 reported cases of primary and secondary syphilis (8.9 cases per 100,000) in Houston, Texas, which was a 58.9% increase from 2002. While syphilis can be completely treated now, unlike in times past, it is still a public health concern. The purpose of this study is to examine the possibility of modeling the impact of an immune response in primary and secondary syphilis in 63 major cities across the United States, stratified by gender and racial-ethnic groups. A Fourier analysis will be performed by SAS. Subsequently, this study will compare the results to a similar study of syphilis in 68 US cities, that focused on immune response, however, did not stratified by race and gender. This study will help determine if the oscillating rates of syphilis are due to biological factors of the disease or to behavioral changes in the population. This study will use surveillance data from 63 major cities across the United States. The data will be provided by the Centers of Disease Control. Ultimately, this study will expand the knowledge of the effect of immunity on endemics.^

Investigations on a sediment core from the Indian Ocean

The Multi-Sensor Core Logger (MSCL) enables non-destructive, quasi-continuous measuroments of physical properties, reducing the time needed for discrete sample analysis. Density, compressional wave velocity (Vp), and magnetic susceptibility are measured on water-saturated sediment cores. Rapid variations in the lithology can thus be more easily recognized. The advantages of MSCL measurements over traditional sedimentological investigation methods are illustrated using several examples. Density-Vp relationships provide detailed lithological information prior to splitting the sediment cores. In terrigenous sediments, density increases with Vp, whereas in biogenic sediments it decreases. In biogenic sediments in the South Atlantic, low densities and high Vp are associated with high opal content. In biogenic sediments in the Peru Basin, density increases with carbonate content. Carbonate, which is very important for deep-sea environmental protection and for paleoclimatic studies, can be determined quantitatively from MSCL measurements in this area. In terrigenous sediments in the Bengal Fan, the acoustic impedance (the product of density and Vp) increases with grain size. There, the grain-size distribution can be rapidly derived from the acoustic impedance. Moreover, in hemipelagic sediments in the Bengal Fan, it is possible to correlate variations in magnetic susceptibility with cyclic changes in the earth's orbital parameters - an important prerequisite for detailed stratigraphic studies.

Magnetostratigraphic age-depth tie points of ODP Leg 208 sites

We report the paleomagnetic and rock magnetic results from discrete sample analysis of sediments from Walvis Ridge, Leg 208 of the Ocean Drilling Program. In an effort to refine the shipboard magnetostratigraphy, alternating field and thermal demagnetization of discrete samples were carried out, predominantly on samples from Sites 1262 and 1267. Results are generally consistent with the shipboard pass-through cryomagnetometer data, though in some cases the discrete samples resolved ambiguities in the reversal record. Significantly, the C24r/C24n reversal boundary was identified at Sites 1262 and 1267, and most boundaries in the Paleocene and Upper Cretaceous sections are now identified to within 10-30 cm. Magnetic mineralogy results show that prior to the late Miocene, the predominant detrital magnetic component was coarse-grained magnetite and that after the late Miocene, titanomagnetite has also been present. This suggests a possible change in detrital source at that time.

Grain shape of sediment from the Weddell Sea

Very fine quartz sand was examined from Paleogene and Neogene sediments of ODP Sites 693, 694, 695, 696, and 697 to determine their grain roundness using Fourier analysis and SEM surface texture characteristics. The objective of this study was to identify grain roundness and surface texture characteristics unique to East (Site 693) and West (Sites 695, 696, and 697) Antarctica and to glacial regimes. Once identified, these distinguishing features could then be used to determine changes in source area and glacial conditions in the central Weddell Sea Basin (Site 694). Three end members of very fine quartz sand are recognized in the Oligocene to Pleistocene sediments of the Weddell Sea: angular, rounded, and intermediate. End member 1 (angular) consists of extremely angular grains with numerous fracture textures. Previous investigations suggested that these sands are derived from crystalline rocks that fractured during formation or deformation and/or were exposed to weathering by ice. In this study, however, the correlation of angularity with ice activity is problematical as the most angular sands were recovered in the lower Oligocene sediments of the South Orkney Microcontinent, a period of temperate climatic conditions. End member 3 (rounded) consists of rounded grains with chemically and mechanically produced surface textures. These sands are presumed to be derived from the Beacon-type rocks in East Antarctica and the sedimentary deposits of the Northern Antarctic Peninsula. End member 2 (intermediate) grains display crystalline nodes and grain embayments. They are thought to be derived from felsic intrusives, East Antarctic quartzites, basement metamorphics of the South Orkney Microcontinent, and/or the Andean intrusive series of West Antarctica. Unfortunately, no features unique to either the East or West Antarctic sediment sources or to glacial conditions could be isolated. Therefore, the objective of determining provenance changes and sediment erosion and transport mechanisms could not be achieved using this approach.

Geographical variation in shell morphology of juvenile snails (Concholepas concholepas) along the physical-chemical gradient of the Chilean coast

Changes in phenotypic traits, such as mollusc shells, are indicative of variations in selective pressure along environmental gradients. Recently, increased sea surface temperature (SST) and ocean acidification (OA) due to increased levels of carbon dioxide in the seawater have been described as selective agents that may affect the biological processes underlying shell formation in calcifying marine organisms. The benthic snail Concholepas concholepas (Muricidae) is widely distributed along the Chilean coast, and so is naturally exposed to a strong physical-chemical latitudinal gradient. In this study, based on elliptical Fourier analysis, we assess changes in shell morphology (outlines analysis) in juvenile C. concholepas collected at northern (23°S), central (33°S) and southern (39°S) locations off the Chilean coast. Shell morphology of individuals collected in northern and central regions correspond to extreme morphotypes, which is in agreement with both the observed regional differences in the shell apex outlines, the high reclassification success of individuals (discriminant function analysis) collected in these regions, and the scaling relationship in shell weight variability among regions. However, these extreme morphotypes showed similar patterns of mineralization of calcium carbonate forms (calcite and aragonite). Geographical variability in shell shape of C. concholepas described by discriminant functions was partially explained by environmental variables (pCO2, SST). This suggests the influence of corrosive waters, such as upwelling and freshwaters penetrating into the coastal ocean, upon spatial variation in shell morphology. Changes in the proportion of calcium carbonate forms precipitated by C. concholepas across their shells and its susceptibility to corrosive coastal waters are discussed.