Impact of Roots

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66547/2/10.1177_002193478601600306.pd

Deterministic and stochastic descriptions of gene expression dynamics

A key goal of systems biology is the predictive mathematical description of gene regulatory circuits. Different approaches are used such as deterministic and stochastic models, models that describe cell growth and division explicitly or implicitly etc. Here we consider simple systems of unregulated (constitutive) gene expression and compare different mathematical descriptions systematically to obtain insight into the errors that are introduced by various common approximations such as describing cell growth and division by an effective protein degradation term. In particular, we show that the population average of protein content of a cell exhibits a subtle dependence on the dynamics of growth and division, the specific model for volume growth and the age structure of the population. Nevertheless, the error made by models with implicit cell growth and division is quite small. Furthermore, we compare various models that are partially stochastic to investigate the impact of different sources of (intrinsic) noise. This comparison indicates that different sources of noise (protein synthesis, partitioning in cell division) contribute comparable amounts of noise if protein synthesis is not or only weakly bursty. If protein synthesis is very bursty, the burstiness is the dominant noise source, independent of other details of the model. Finally, we discuss two sources of extrinsic noise: cell-to-cell variations in protein content due to cells being at different stages in the division cycles, which we show to be small (for the protein concentration and, surprisingly, also for the protein copy number per cell) and fluctuations in the growth rate, which can have a significant impact.Comment: 23 pages, 5 figures; Journal of Statistical physics (2012

Antigen-Presenting Activity of Non-Langerhans Epidermal Cells in Contact Hypersensitivity Reactions

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72263/1/j.1365-3083.1990.tb02914.x.pd

Quantitative comparison of single- and two-particle properties in the cuprates

We explore the strong variations of the electronic properties of copper-oxygen compounds across the doping phase diagram in a quantitative way. To this end we calculate the electronic Raman response on the basis of results from angle-resolved photoemission spectroscopy (ARPES). In the limits of our approximations we find agreement on the overdoped side and pronounced discrepancies at lower doping. In contrast to the successful approach for the transport properties at low energies, the Raman and the ARPES data cannot be reconciled by adding angle-dependent momentum scattering. We discuss possible routes towards an explanation of the suppression of spectral weight close to the $(\pi,0)$ points which sets in abruptly close to 21% doping.Comment: 7 pages, 4 figure

A dynamical model of lipoprotein metabolism

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Pesticide And Transformation Product Detections And Age-Dating Relations From Till And Sand Deposits

Pesticide and transformation product concentrations and frequencies in ground water from areas of similar crop and pesticide applications may vary substantially with differing lithologies. Pesticide analysis data for atrazine, metolachlor, alachlor, acetochlor, and cyanazine and their pesticide transformation products were collected at 69 monitoring wells in Illinois and northern Indiana to document occurrence of pesticides and their transformation products in two agricultural areas of differing lithologies, till, and sand. The till is primarily tile drained and has preferential fractured flow, whereas the sand primarily has surface water drainage and primary porosity flow. Transformation products represent most of the agricultural pesticides in ground water regardless of aquifer material – till or sand. Transformation products were detected more frequently than parent pesticides in both the till and sand, with metolachlor ethane sulfonic acid being most frequently detected. Estimated ground-water recharge dates for the sand were based on chlorofluorocarbon analyses. These age-dating data indicate that ground water recharged prior to 1990 is more likely to have a detection of a pesticide or pesticide transformation product. Detections were twice as frequent in ground water recharged prior to 1990 (82%) than in ground water recharged on or after 1990 (33%). The highest concentrations of atrazine, alachlor, metolachlor, and their transformation products, also were detected in samples from ground water recharged prior to 1990. These age ⁄ pesticide detection relations are opposite of what would normally be expected, and may be the result of preferential flow and ⁄ or ground-water mixing between aquifers and aquitards as evident by the detection of acetochlor transformation products in samples with estimated ground-water ages predating initial pesticide application

Multimodal therapy in an inpatient setting

Inpatient Multimodal Therapy (imt) is a residential treatment program, lasting a maximum of 36 weeks, for patients with severe neurotic symptoms. A group of 44 chronic obsessive-compulsive patients and a group of 40 chronic phobic patients were treated in order to assess the outcome and the process of treatment and to identify prognostic factors associated with the effect. At follow-up-on average, eight months after discharge-it was found that 60% had improved, 32% had remained the same, and 8% had deteriorated, indicating that, in general, the treatment was beneficial. That these effects were long-lasting is supported by the fact that, at follow-up, 78% of all patients were no longer receiving treatment, 18% were receiving outpatient or day treatment, and 4% were receiving inpatient treatment. Phobic patients appear to have gained more from the multimodal approach than did obsessive-compulsive patients, as indicated by the fact that the severity of symptoms decreased as they improved in rational thinking, assertiveness, and arousal. By contrast, obsessive-compulsive patients relapsed more than phobic patients did. This was attributed to the fact that the former gained less from the rational-emotive training, denied problems with assertiveness, and did not practice the acquired relaxation skills. It further appeared that a favorable outcome could be induced in patients who (1) expressed relatively mild symptoms in this otherwise severe group, (2) reported relatively few additional complaints, (3) could clearly indicate interpersonal problems, and (4) did not use psychotropic drugs. These prognostic factors are so widespread that not much weight can be ascribed to them. Yet they are useful for indication of imt until better predictors are found

The irreversibility line of overdoped Bi_{2+x}Sr_{2-(x+y)}Cu_{1+y}O_{6 +- delta} at ultra-low temperatures and high magnetic fields

The irreversible magnetization of the layered high-T_{c} superconductor Bi_{2+x}Sr_{2-(x+y)}Cu_{1+y}O_{6 +- delta} (Bi-2201) has been measured by means of a capacitive torquemeter up to B=28 T and down to T=60 mK. No magnetization jumps, peak effects or crossovers between different pinning mechanisms appear to be present. The deduced irreversibility field B_{irr} can not be described by the law B_{irr}(T)=B_{irr}(0)(1-T/T_{c})^n based on flux creep, but an excellent agreement is found with the analytical form of the melting line of the flux lattice as calculated from the Lindemann criterion. The behavior of B_{irr}(T) obtained here is very similar to the resistive critical field of a Bi-2201 thin film, suggesting that magnetoresistive experiments are likely to be strongly influenced by flux lattice melting.Comment: 4 pages, 4 eps figure

Observation of Orbitally Excited B_s Mesons

We report the first observation of two narrow resonances consistent with states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+, \bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1}) = 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let