5,132 research outputs found
Simulated lumped-parameter system reduced-order adaptive control studies
Two methods of interpreting the misbehavior of reduced order adaptive controllers are discussed. The first method is based on system input-output description and the second is based on state variable description. The implementation of the single input, single output, autoregressive, moving average system is considered
Optimizing the Oil Extraction/Water Adsorption Step in Sequential Extraction Processing of Corn
The Sequential Extraction Process (SEP) uses ethanol to extract oil and protein from cracked, flaked, and dried corn, and the corn simultaneously dehydrates the ethanol. The optimum conditions to reduce zein extraction in the oil extraction/water adsorption step of SEP involved a singleâpass system using 15 length/diameter ratio extraction cells, 30% hexanes: 70% ethanol, and 56C extraction temperature, which improved the efficiencies of oil extraction from the corn and moisture adsorption from the ethanol. The extract contained only 0.1% protein in the desolventized solids. The moisture content of the solvent was reduced to 1.03%, and the residual oil content of the corn was 0.18%. Oil recovery was improved from 90.8% to 95.5%. The countercurrent laboratory extraction system confirmed that using 30% hexanes:70% ethanol at 56C in a singleâpass system reduced zein coâextraction with oil while increasing oil extraction and moisture adsorption
Clustering of multiple specific genes and gene-rich R-bands around SC-35 domains: evidence for local euchromatic neighborhoods
Typically, eukaryotic nuclei contain 10â30 prominent domains (referred to here as SC-35 domains) that are concentrated in mRNA metabolic factors. Here, we show that multiple specific genes cluster around a common SC-35 domain, which contains multiple mRNAs. Nonsyntenic genes are capable of associating with a common domain, but domain âchoiceâ appears random, even for two coordinately expressed genes. Active genes widely separated on different chromosome arms associate with the same domain frequently, assorting randomly into the 3â4 subregions of the chromosome periphery that contact a domain. Most importantly, visualization of six individual chromosome bands showed that large genomic segments (âŒ5 Mb) have striking differences in organization relative to domains. Certain bands showed extensive contact, often aligning with or encircling an SC-35 domain, whereas others did not. All three gene-rich reverse bands showed this more than the gene-poor Giemsa dark bands, and morphometric analyses demonstrated statistically significant differences. Similarly, late-replicating DNA generally avoids SC-35 domains. These findings suggest a functional rationale for gene clustering in chromosomal bands, which relates to nuclear clustering of genes with SC-35 domains. Rather than random reservoirs of splicing factors, or factors accumulated on an individual highly active gene, we propose a model of SC-35 domains as functional centers for a multitude of clustered genes, forming local euchromatic âneighborhoods.
Characterizing the effect of glutamine supplementation on asparagine and glutamine metabolism using 13C metabolic flux analysis
Upstream development efforts often focus on improved productivity. Among those efforts, improvements in medium formulations have translated into greater titers. To continue this historical trend, a better understanding of the cell metabolism is warranted for guiding efficient utilization of medium components to improve titer while minimizing byproducts. 13C Metabolic Flux Analysis (13C MFA) offers opportunities to study metabolic phenotypes by applying isotope tracers to estimate the intracellular fluxes through metabolic pathways.
In this work, 13C MFA was applied to study the effects of glutamine supplementation by 13C parallel labelling of cultures with [U-13C]asparagine, [U-13C]glutamine and an a mixture of [U-13C]glucose with [1,2-13C]glucose. The study was focused on two metabolic states characterized by glutamine consumption in the early exponential phase and glutamine production in the late exponential phase of a fed-batch culture. To quantify individual metabolic pathway activity, metabolic flux maps were generated for the glutamine supplemented feeds compared to a control case with glutamine in the initial medium. The glutamine supplementation condition resulted in redistribution of the fluxes in the TCA cycle. Furthermore, measurements of the enrichment of cell protein indicate different allocations of the fed nutrients into generated biomass for the glutamine supplemented condition. Comparison between the early and the late exponential phases provided novel insights on how glutamine modulates CHO central carbon metabolism and supports the important role of glutamine as a major source of energy for cell proliferation. These findings contribute towards an improved characterization of the metabolism of industrial cells with useful implications for optimizing medium and feed development
Tumor site immune markers associated with risk for subsequent basal cell carcinomas.
BackgroundBasal cell carcinoma (BCC) tumors are the most common skin cancer and are highly immunogenic.ObjectiveThe goal of this study was to assess how immune-cell related gene expression in an initial BCC tumor biopsy was related to the appearance of subsequent BCC tumors.Materials and methodsLevels of mRNA for CD3Δ (a T-cell receptor marker), CD25 (the alpha chain of the interleukin (IL)-2 receptor expressed on activated T-cells and B-cells), CD68 (a marker for monocytes/macrophages), the cell surface glycoprotein intercellular adhesion molecule-1 (ICAM-1), the cytokine interferon-Îł (IFN-Îł) and the anti-inflammatory cytokine IL-10 were measured in BCC tumor biopsies from 138 patients using real-time PCR.ResultsThe median follow-up was 26.6 months, and 61% of subjects were free of new BCCs two years post-initial biopsy. Patients with low CD3Δ CD25, CD68, and ICAM-1 mRNA levels had significantly shorter times before new tumors were detected (pâ=â0.03, pâ=â0.02, pâ=â0.003, and pâ=â0.08, respectively). Furthermore, older age diminished the association of mRNA levels with the appearance of subsequent tumors.ConclusionsOur results show that levels of CD3Δ, CD25, CD68, and ICAM-1 mRNA in BCC biopsies may predict risk for new BCC tumors
Why Effective Medium Theory Fails in Granular Materials
Experimentally it is known that the bulk modulus, K, and shear modulus, \mu,
of a granular assembly of elastic spheres increase with pressure, p, faster
than the p^1/3 law predicted by effective medium theory (EMT) based on
Hertz-Mindlin contact forces. To understand the origin of these discrepancies,
we perform numerical simulations of granular aggregates under compression. We
show that EMT can describe the moduli pressure dependence if one includes the
increasing number of grain-grain contacts with p. Most important, the affine
assumption (which underlies EMT), is found to be valid for K(p) but breakdown
seriously for \mu(p). This explains why the experimental and numerical values
of \mu(p) are much smaller than the EMT predictions.Comment: 4 pages, 5 figures, http://polymer.bu.edu/~hmaks
Does Coping Matter? Coping and Chronic Physiological Distress Among Aging U.S. Black and White Men
AbstractChronic physiological distress accelerates biological aging and is linked to chronic disease and premature mortality. Physiological distress biomarkers, such as cortisol, represent a key proximal outcome of stress and coping processes through which social inequities are posited to generate health disparities. This study explored how variations in coping may contribute to documented racial disparities in chronic physiological distress between midlife and older Black and White male participants in the National Survey of Midlife Development in the United States (MIDUS) II and the National Study of Daily Experiences (NSDE) II. Black and White men generally reported using similar coping strategies, though Black men relied more on positive reinterpretation, denial, drug use, and physical inactivity than White men. Of the 12 coping strategies examined, ten were unrelated to menâs chronic physiological distress levels. Religious and spiritual coping appeared protective, but only for White men. Black men who reported drug use (i.e., illegal drugs, prescription drug misuse) had less chronic physiological distress than those who abstained; drug use was unrelated to White menâs distress. Findings suggest that how older adult men cope may not be an important determinant of whether they exhibit chronic physiological distress. Our evidence also does not support conventional categorization of coping strategies as âgoodâ or âbad.â Reducing racial health disparities among men may instead necessitate mitigating sources of stress implicated in chronic physiological distress, such as racism. More research investigating our unanticipated findings holds promise for developing targeted interventions to reduce racial disparities in chronic physiological distress among men.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150674/1/Abstract Allen Watkins Chatters Johnson-Lawrence 2018 Does Coping Matter.pd
An Exact String Theory Model of Closed Time-Like Curves and Cosmological Singularities
We study an exact model of string theory propagating in a space-time
containing regions with closed time-like curves (CTCs) separated from a finite
cosmological region bounded by a Big Bang and a Big Crunch. The model is an
non-trivial embedding of the Taub-NUT geometry into heterotic string theory
with a full conformal field theory (CFT) definition, discovered over a decade
ago as a heterotic coset model. Having a CFT definition makes this an excellent
laboratory for the study of the stringy fate of CTCs, the Taub cosmology, and
the Milne/Misner-type chronology horizon which separates them. In an effort to
uncover the role of stringy corrections to such geometries, we calculate the
complete set of alpha' corrections to the geometry. We observe that the key
features of Taub-NUT persist in the exact theory, together with the emergence
of a region of space with Euclidean signature bounded by time-like curvature
singularities. Although such remarks are premature, their persistence in the
exact geometry is suggestive that string theory theory is able to make physical
sense of the Milne/Misner singularities and the CTCs, despite their
pathological character in General Relativity. This may also support the
possibility that CTCs may be viable in some physical situations, and may be a
natural ingredient in pre-Big-Bang cosmological scenarios.Comment: 37 pages, 4 figures. V2: discussion of computation of metric refined,
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Lack of Association Between 25(OH)D Levels and Incident Type 2 Diabetes in Older Women
Objective: To examine whether lower serum levels of serum 25-hydroxyvitamin (OH) D [25(OH)D] are associated with increased risk of developing type 2 diabetes. Research Design and Methods: A post hoc analysis of three nested case-control studies of fractures, colon cancer, and breast cancer that measured serum 25(OH)D levels in women participating in the Womenâs Health Initiative (WHI) Clinical Trials and Observational Study who were free of prevalent diabetes at baseline. Diabetes was defined as self-report of physician diagnosis or receiving insulin or oral hypoglycemic medication. We used inverse probability weighting to make the study population representative of the WHI population as a whole. Weighted logistic regression models compared 25(OH)D levels (divided into quartiles, clinical cut points [<50, 50â<75, 75 nmol/L], or as a continuous variable) using the distribution of control subjects and adjusted for multiple confounding factors. Results: Of 5,140 women (mean age 66 years) followed for an average of 7.3 years, 317 (6.2%) developed diabetes. Regardless of the cut points used or as a continuous variable, 25(OH)D levels were not associated with diabetes incidence in either age or fully adjusted models. Nor was any relationship found between 25(OH)D and incident diabetes when evaluated by strata of BMI, race/ethnicity, or randomization status in the Calcium Vitamin D trial. Conclusions: Lower serum 25(OH)D levels were not associated with increased risk of developing type 2 diabetes in this racially and ethnically diverse population of postmenopausal women
Nonrandom gene organization: structural arrangements of specific pre-mRNA transcription and splicing with SC-35 domains.
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