Simultaneous flow of water and air across the land surface during runoff

This paper presents an inter-compartment boundary condition for the simulation of surface runoff, soil moisture, and soil air as a coupled system of partial differential equations. The boundary condition is based on a classic leakance approach to balance water between differently mobile regions such as the land surface and subsurface. Present work applies leakances to transfer water and air simultaneously through the land surface for soils, which are connected by an air flux with a steady atmosphere. Shallow flow and two phase flow in a porous medium are sequential calculated in an iteration loop. General criteria are stated to guarantee numerical stability in the coupling loop and for leakances to control inter-compartment fluid fluxes. Using the leakance approach, a numerical model captures typical feedbacks between surface runoff and soil air in near-stream areas. Specifically, displacement of water and air in soils is hampered at full-water saturation over the land surface resulting in enhanced surface runoff in the test cases. Leakance parameters permit the simulation of air out-breaks with reference to air pressures, which fluctuate in the shallow subsurface between two thresholds

Proton Spin Relaxation Induced by Quantum Tunneling in Fe8 Molecular Nanomagnet

The spin-lattice relaxation rate $T_{1}^{-1}$ and NMR spectra of $^1$H in single crystal molecular magnets of Fe8 have been measured down to 15 mK. The relaxation rate $T_1^{-1}$ shows a strong temperature dependence down to 400 mK. The relaxation is well explained in terms of the thermal transition of the iron state between the discreet energy levels of the total spin S=10. The relaxation time $T_1$ becomes temperature independent below 300 mK and is longer than 100 s. In this temperature region stepwise recovery of the $^1$H-NMR signal after saturation was observed depending on the return field of the sweep field. This phenomenon is attributed to resonant quantum tunneling at the fields where levels cross and is discussed in terms of the Landau-Zener transition.Comment: 13 pages, 5 figure

Properties of low-lying states in some high-nuclearity Mn, Fe and V clusters: Exact studies of Heisenberg models

Using an efficient numerical scheme that exploits spatial symmetries and spin parity, we have obtained the exact low-lying eigenstates of exchange Hamiltonians for the high nuclearity spin clusters, Mn_{12}, Fe_8 and V_{15}. The largest calculation involves the Mn_{12} cluster which spans a Fock space of a hundred million. Our results show that the earlier estimates of the exchange constants need to be revised for the Mn_{12} cluster to explain the level ordering of low-lying eigenstates. In the case of the Fe_8 cluster, correct level ordering can be obtained which is consistent with the exchange constants for the already known clusters with butterfly structure. In the V_{15} cluster, we obtain an effective Hamiltonian that reproduces exactly, the eight low-lying eigenvalues of the full Hamiltonian.Comment: Revtex, 12 pages, 16 eps figures; this is the final published versio

High frequency resonant experiments in Fe8_8 molecular clusters

Precise resonant experiments on Fe$_{8}$ magnetic clusters have been conducted down to 1.2 K at various tranverse magnetic fields, using a cylindrical resonator cavity with 40 different frequencies between 37 GHz and 110 GHz. All the observed resonances for both single crystal and oriented powder, have been fitted by the eigenstates of the hamiltonian ${\cal H}=-DS_z^2+ES_x^2-g\mu_B{\bf H}\cdot {\bf S}$. We have identified the resonances corresponding to the coherent quantum oscillations for different orientations of spin S = 10.Comment: to appear in Phys.Rev. B (August 2000

Evaluating Remediation Potential Of A Salinized Heterogeneous Aquifer System Using Three-Dimensional, Density-Dependent Groundwater Modeling

In arid regions, groundwater is the most reliable source for freshwater. Thus, ensuring an aquifer’s long-term stability is one of the fundamental tasks for nowadays groundwater management. Especially in agriculturally used coastal regions, where water consumption exceeds annual recharge, water table drawdown and subsequent saline intrusion are problems that need to be addressed. Wihin the context of the government-funded research project „International Water ResearchAlliance Saxony“, groundwater quality for near-coastal, agriculturally used areas was investigated under the influence of marine saltwater intrusion. In the study region’s near-coastal areas, agricultural development increased tremendously during recent decades, while a steady lowering of the groundwater level was observed, which is primarily due to uncontrolled groundwater mining. Extracted water is mainly used for local irrigation. Intensively decreased groundwater levels, cause an inversion of the hydraulic gradient leading to intrusion of marine saltwater, endangering the productivity of farms. Utilizing the modeling software package OpenGeoSys, which is developed and enhanced by the Department of Environmental Informatics at UFZ Leipzig (Kolditz et al., 2012), a three-dimensional, density-dependent model including groundwater flow and mass transport was built up (Walther, et al., 2012a). The model comprises a heterogeneous hydro-geology (Walther et al., 2012b). A pre-development steady-state was calibrated successfully offering initial conditions for an adjacent transient calibration yielding acceptable results within apparent uncertainties of input parameters. The numerical model was used to investigate a best-case scenario assessing remediation potential of the salinized aquifer. The scenario considers ceasing groundwater abstraction and evaluates time scale and spatial distribution along the coast of the saltwater retreat. Using advanced visualization techniques in a virtual reality (Walther et al., 2013), results show a heterogeneous distribution of the saltwater withdrawal. Remediation actions will require a long-term strategy to retreive the already salinized regions of the aquifer. Results reveal valuable insight for future measurement campaings and management

Nuclear spin-lattice relaxation in ferrimagnetic clusters and chains: A contrast between zero and one dimensions

Motivated by ferrimagnetic oligonuclear and chain compounds synthesized by Caneschi et al., both of which consist of alternating manganese(II) ions and nitronyl-nitroxide radicals, we calculate the nuclear spin-lattice relaxation rate 1/T_1 employing a recently developed modified spin-wave theory. 1/T_1 as a function of temperature drastically varies with the location of probe nuclei in both clusters and chains, though the relaxation time scale is much larger in zero dimension than in one dimension. 1/T_1 as a function of an applied field in long chains forms a striking contrast to that in finite clusters, diverging with decreasing field like inverse square root at low temperatures and logarithmically at high temperatures.Comment: to be published in Phys. Rev. B 68 August 01 (2003

External validation of serum hCG cutoff levels for prediction of resistance to single-agent chemotherapy in patients with persistent trophoblastic disease

Van Trommel et al have previously shown that serum human chorionic gonadotropin (hCG) cutoff levels can provide early prediction of resistance to first-line methotrexate (MTX) in patients with persistent trophoblastic disease (PTD). In this study, we validate this approach of prediction of resistance to single-agent chemotherapy in an independent and larger cohort of PTD patients using a different hCG assay. Receiver operating characteristics (ROC) curves were constructed to determine hCG cutoff levels and sensitivity between patients cured on single-agent chemotherapy (control group) and patients requiring change to combination chemotherapy (study group). Receiver operating characteristics analysis identified an hCG cutoff value of 737 IU l−1 that enabled us to predict the subsequent development of single-agent chemotherapy resistance in 52% of patients before their fourth MTX course at 97.5% specificity. This would have enabled an earlier switch to combination chemotherapy reducing the MTX exposure by an average of 2.5 courses. The present findings confirm that serum hCG cutoff levels predict resistance to single-agent therapy earlier than traditional methods. Change to combination chemotherapy should be considered for patients whose serum hCG levels exceed these hCG cutoff values. For patients not exceeding the hCG cutoff levels, static or rising hCG levels should still be included in the criteria for change of chemotherapy

Diary of an internship with the Federal Probation and Parole Office, Tucson District of Arizona

Please contact [email protected] if you wish to view this title.Diary in lieu of thesis (M.P.A. - Public Administration)--University of Arizona

Punching Up – Punching Down: Humor as a Tool of Subversion in the Íslendingasögur

Humor is, without question, an intrinsic part of the þættir and sagas of medieval Iceland. Many of the sagas and þættir have humorous moments, ranging from physical humor to ironic comments to insulting verses. The humorous incidents that are chosen by the authors of the sagas and þættir reflect both the authors’ purposes in writing the sagas and the internal condition of the characters. They may also give a clue to the state of mind of the societies in which they take place and in which they were written. This paper proposes that humorous incidents in the sagas are not random; they serve a variety of purposes. Among the purposes these incidents serve is the subversion of people’s intentions and reputations, and of corrupt institutions. Such criticism is sharpened by the use of humor. By looking at the sagas and þættir through the lens of the Aggression Theory of Humor, posed by Igor Krichtafovich, which is comprised of Superiority Theory, as explained by John Morreall; and Inferiority Theory, proposed by Robert Solomon, we can understand how the humor of the sagas and þættir can be viewed as a subversive tool. This paper will look at Brennu-Njáls saga, Ǫlkofra þáttr, Sneglu-Halla þáttr, and Kormáks saga in an effort to arrive at an understanding of the subversive humor of the medieval Icelandic saga and þættir, to gain a better knowledge of how humor works in medieval Icelandic literature in general, and to lay the groundwork for further studies in medieval Icelandic humor. Kímni er án efa mikilvægur þáttur í Íslendingasögum og Íslendingaþáttum. Í mörgum þeirra eru gamansöm andartök og geta það verið líkamleg fyndni, kaldhæðnar athugasemdir og móðgandi vísur. Segja má að þau gamansömu atvik sem rata í sögur endurspegli bæði tilgang höfundar og innra ástand persónanna. Eins veita þau innsýn í samfélagið bæði á sögutíma og ritunartíma.   Í þessari ritgerð er gert ráð fyrir að gamansemi sagnanna sé engan veginn handahófskennd heldur þjóni margvíslegum tilgangi. Þar á meðal að afhjúpa og snúa á haus fyrirætlunum og heiðri manna og spilltra stofnana. Þannig getur gamansemin yddað gagnrýni. Með því að beita árásargirnikenningu Igor Krichtafovich þar sem sameinaðar eru yfirburðakenning John Morreall og minnkunarkenning Robert Solomon má varpa ljósi á það hvernig gamansemin er iðulega gagnrýnin og afhjúpandi í Íslendingasögum og Íslendingaþáttum.  Í þessari rannsókn er sjónum einkum beint að Brennu-Njáls sögu, Ölkofra þætti, Sneglu-Halla þætti og Kormáks sögu til að auka skilning á gagnrýninni gamansemi í Íslendingasögum og Íslendingaþáttum en um leið til að varpa frekara ljósi á hvernig gamansemi virkar í íslenskum miðaldabókmenntum yfirleitt og leggja þar með grunn að frekari rannsóknum á íslenskum miðaldahúmor