Critical behavior of a system with orientational and positional degrees of freedom: A Monte Carlo simulation study

The critical behavior of a system constituted by molecules with a preferred symmetry axis is studied by means of a Monte Carlo simulation of a simplified two-dimensional model. The system exhibits two phase transitions, associated with the vanishing of the positional order of the center of mass of the molecules and with the orientational order of the symmetry axis. The evolution of the order parameters and the specific heat is also studied. The transition associated with the positional degrees of freedom is found to change from a second-order to a first-order behavior when the two phase transitions are close enough, due to the coupling with the orientational degrees of freedom. This fact is qualitatively compared with similar results found in pure liquid crystals and liquid-crystal mixtures.

RAGBRAI Learn about the Land; Day 1, July 2011

Want to know what conditions to expect over the next stage of RAGBRAI? How hilly will it be, what towns and parks are between here and there, or what services are coming up in the next town?

RAGBRAI Learn about the Land; Day 2, July 2011

The University of Iowa Office of the State Archaeologist and Team Archaeology are back on RAGBRAI for another year of Archaeology on the Road, and pleased to partner this year with the IDNR: Geological and Water Survey and the U.S. Geological Survey under the theme “Human and Natural History Partners.” Archaeology on the Road brings you the unique cultural history and prehistory of Iowa on the RAGBRAI route, pointing out interesting and significant archaeological sites and sharing Iowa’s past along the way. Look for our booth at Expo and then again on Days 1, 5 and 6 on the route, and also keep an eye out for our Team Archaeology

RAGBRAI Learn about the Land; Day 3, July 2011

The University of Iowa Office of the State Archaeologist and Team Archaeology are back on RAGBRAI for another year of Archaeology on the Road, and pleased to partner this year with the IDNR: Geological and Water Survey and the U.S. Geological Survey under the theme “Human and Natural History Partners.” Archaeology on the Road brings you the unique cultural history and prehistory of Iowa on the RAGBRAI route, pointing out interesting and significant archaeological sites and sharing Iowa’s past along the way. Look for our booth at Expo and then again on Days 1, 5 and 6 on the route, and also keep an eye out for our Team Archaeology

RAGBRAI Learn about the Land; Day 4, July 2011

The University of Iowa Office of the State Archaeologist and Team Archaeology are back on RAGBRAI for another year of Archaeology on the Road, and pleased to partner this year with the IDNR: Geological and Water Survey and the U.S. Geological Survey under the theme “Human and Natural History Partners.” Archaeology on the Road brings you the unique cultural history and prehistory of Iowa on the RAGBRAI route, pointing out interesting and significant archaeological sites and sharing Iowa’s past along the way. Look for our booth at Expo and then again on Days 1, 5 and 6 on the route, and also keep an eye out for our Team Archaeology

RAGBRAI Learn about the Land; Day 5, July 2011

The University of Iowa Office of the State Archaeologist and Team Archaeology are back on RAGBRAI for another year of Archaeology on the Road, and pleased to partner this year with the IDNR: Geological and Water Survey and the U.S. Geological Survey under the theme “Human and Natural History Partners.” Archaeology on the Road brings you the unique cultural history and prehistory of Iowa on the RAGBRAI route, pointing out interesting and significant archaeological sites and sharing Iowa’s past along the way. Look for our booth at Expo and then again on Days 1, 5 and 6 on the route, and also keep an eye out for our Team Archaeology.

RAGBRAI Learn about the Land; Day 7, July 2011

The University of Iowa Office of the State Archaeologist and Team Archaeology are back on RAGBRAI for our third year of Archaeology on the Road, and pleased to partner this year with the IDNR: Geological and Water Survey and the U.S. Geological Survey under the theme “Human and Natural History Partners.” Archaeology on the Road brings you the unique cultural history and prehistory of Iowa on the RAGBRAI route, pointing out interesting and significant archaeological sites and sharing Iowa’s past along the way. Look for our booth at Expo and then again on Days 1, 5 and 6 on the route, and also keep an eye out for our Team Archaeology.

Intensity correlation function of dye lasers: Short-time behavior

We propose an equation to calculate the intensity correlation function of a dye-laser model with a pump parameter subject to finite-bandwidth fluctuations. The equation is valid, in the weak-noise limit, for all times. It incorporates novel non-Markovian features. Results are given for the short-time behavior of the correlation function. It exhibits a characteristic initial plateau. Our findings are supported by a numerical simulation of the model.

From nonwetting to prewetting: The asymptotic behavior of 4He drops on alkali substrates

We investigate the spreading of 4He droplets on alkali-metal surfaces at zero temperature, within the frame of finite range density-functional theory. The equilibrium configurations of several 4HeN clusters and their asymptotic trend with increasing particle number N, which can be traced to the wetting behavior of the quantum fluid, are examined for nanoscopic droplets. We discuss the size effects inferring that the asymptotic properties of large droplets correspond to those of the prewetting film.

Structural changes in latosols of the cerrado region: II - soil compressive behavior and modeling of additional compaction

Currently in Brazil, as in other parts of the world, the concern is great with the increase of degraded agricultural soil, which is mostly related to the occurrence of soil compaction. Although soil texture is recognized as a very important component in the soil compressive behaviors, there are few studies that quantify its influence on the structural changes of Latosols in the Brazilian Cerrado region. This study aimed to evaluate structural changes and the compressive behavior of Latosols in Rio Verde, Goiás, through the modeling of additional soil compaction. The study was carried out using five Latosols with very different textures, under different soil compaction levels. Water retention and soil compression curves, and bearing capacity models were determined from undisturbed samples collected on the B horizons. Results indicated that clayey and very clayey Latosols were more susceptible to compression than medium-textured soils. Soil compression curves at density values associate with edaphic functions were used to determine the beneficial pressure (σ b) , i.e., pressure with optimal water retention, and critical pressure (σcrMAC), i.e., pressure with macroporosity below critical levels. These pressure values were higher than the preconsolidation pressure (σp), and therefore characterized as additional compaction. Based on the compressive behavior of these Latosols, it can be concluded that the combined preconsolidation pressure, beneficial pressure and critical pressure allow a better understanding of compression processes of Latosols.

Routine therapeutic drug monitoring in patients treated with 10-360 mg/day citalopram

From data collected during routine TDM, plasma concentrations of citalopram (CIT) and its metabolites demethylcitalopram (DCIT) and didemethylcitalopram (DDCIT) were measured in 345 plasma samples collected in steady-state conditions. They were from 258 patients treated with usual doses (20-60 mg/d) and from patients medicated with 80-360 mg/d CIT. Most patients had one or several comedications, including other antidepressants, antipsychotics, lithium, anticonvulsants, psychostimulants and somatic medications. Dose-corrected CIT plasma concentrations (C/D ratio) were 2.51 +/- 2.25 ng mL-1 mg-1 (n = 258; mean +/- SD). Patients >65 years had significantly higher dose-corrected CIT plasma concentrations (n = 56; 3.08 +/- 1.35 ng mL-1 mg-1) than younger patients (n = 195; 2.35 +/- 2.46 ng mL-1 mg-1) (P = 0.03). CIT plasma concentrations in the generally recommended dose range were [mean +/- SD, (median)]: 57 +/- 64 (45) ng/mL (10-20 mg/d; n = 64), 117 +/- 95 (91) ng/mL (21-60 mg/d; n = 96). At higher than usual doses, the following concentrations of CIT were measured: 61-120 mg/d CIT, 211 +/- 103 (190) ng/mL (n = 93); 121-200 mg/d: 339 +/- 143 (322) ng/mL (n = 70); 201-280 mg/d: 700 +/- 408 (565) ng/mL (n = 18); 281-360 mg/d: 888 +/- 620 (616) ng/mL (n = 4). When only one sample per patient (at the highest daily dose if repeated dosages) is considered, there is a linear and significant correlation (n = 48, r = 0.730; P < 0.001) between daily dose (10-200 mg/d) and CIT plasma concentrations. In experiments with dogs, DDCIT was reported to affect the QT interval when present at concentrations >300 ng/mL. In this study, DDCIT concentration reached 100 ng/mL in a patient treated with 280 mg/d CIT. Twelve other patients treated with 140-320 mg/d CIT had plasma concentrations of DDCIT within the range 52-73 ng/mL. In a subgroup comprised of patients treated with > or =160 mg/d CIT and with CIT plasma concentrations < or =300 ng/mL, and patients treated with < or =200 mg/d CIT and CIT plasma concentrations > or = 600 ng/mL, the enantiomers of CIT and DCIT were also analyzed. The highest S-CIT concentration measured in this subgroup was 327 ng/mL in a patient treated with 140 mg/d CIT, but the highest S-CIT concentration (632 ng/mL) was measured in patient treated with 360 mg/d CIT. In conclusion, there is a highly linear correlation between CIT plasma concentrations and CIT doses, well above the usual dose range.

Examining Driver Behavior in Response to Work Zone Interventions: A Driving Simulator Study, 2010

Construction zones pose a significant threat to both workers and drivers causing numerous injuries and deaths each year. Innovations in work zone safety could reduce these numbers. However, implementing work zone interventions before they are validated can undermine rather than enhance safety. The objective of this research is to demonstrate how driving simulators can be used to evaluate the effect of various work zone interventions on driver performance.

Zenith angle distributions at Super-Kamiokande and SNO and the solution of the solar neutrino problem

We have performed a detailed study of the zenith angle dependence of the regeneration factor and distributions of events at SNO and SK for different solutions of the solar neutrino problem. In particular, we discuss the oscillatory behavior and the synchronization effect in the distribution for the LMA solution, the parametric peak for the LOW solution, etc. A physical interpretation of the effects is given. We suggest a new binning of events which emphasizes the distinctive features of the zenith angle distributions for the different solutions. We also find the correlations between the integrated day-night asymmetry and the rates of events in different zenith angle bins. The study of these correlations strengthens the identification power of the analysis.