962 research outputs found
Genomic stuff: Governing the (im)matter of life
Emphasizing the context of what has often been referred to as âscarce natural resourcesâ, in particular forests, meadows, and fishing stocks, Elinor Ostromâs important work Governing the commons (1990) presents an institutional framework for discussing the development and use of collective action with respect to environmental problems. In this article we discuss extensions of Ostromâs approach to genes and genomes and explore its limits and usefulness. With the new genetics, we suggest, the biological gaze has not only been turned inward to the management and mining of the human body, also the very notion of the âbiologicalâ has been destabilized. This shift and destabilization, we argue, which is the result of human refashioning and appropriation of âlife itselfâ, raises important questions about the relevance and applicability of Ostromâs institutional framework in the context of what we call âgenomic stuffâ, genomic material, data, and information
Thermoelectric power in one-dimensional Hubbard model
The thermoelectric power S is studied within the one-dimensional Hubbard
model using the linear response theory and the numerical exact-diagonalization
method for small systems. While both the diagonal and off-diagonal dynamical
correlation functions of particle and energy current are singular within the
model even at temperature T>0, S behaves regularly as a function of frequency
and T. Dependence on the electron density n below the half-filling
reveals a change of sign of S at n_0=0.73+/-0.07 due to strong correlations, in
the whole T range considered. Approaching half-filling S is hole-like and can
become large for U>>t although decreasing with T.Comment: 6 pages, 4 figure
Iron status in 6-y-old children: associations with growth and earlier iron status
To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldOBJECTIVE: To investigate the iron status of 6-y-old children and its association with growth and earlier iron status. DESIGN: In a cross-sectional study, children's body size measurements were recorded and blood samples taken near their sixth birthday. SUBJECTS: A sample of 188 children, randomly selected in two previous studies, was contacted, and 139(74%) agreed to participate. RESULTS: No children had iron deficiency anaemia, one was iron-deficient (serum ferritin (SF) or =15 microg/l (258+/-31%; n=49) (P=0.001). MCV at 2 y predicted weight gain from 2 to 6 y (B+/-s.e.=1.721+/-0.581; P=0.005; adj. R2=0.153) (n=44); also, children with SF or =15 microg/l (n=35) gained 9.6+/-2.8 kg (P=0.007), furthermore a difference was seen in proportional weight gain from 2 to 6 y between children with depleted iron stores at 2 y and not, or 156+/-13 vs 169+/-18% (P=0.038). CONCLUSION: The results suggest that low iron status at 1 and 2 y might lead to slower growth up to 6 y of age. Low iron status at 1 and 2 y and/or slower growth from 1 and 2 y up to 6 y might contribute to worse iron status at 6 y, while faster growth in early childhood is related to lower iron status
Associations of iron status with dietary and other factors in 6-year-old children
To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldOBJECTIVE: To investigate the associations of iron status at 6 years of age with dietary and other factors. DESIGN: In a cross-sectional study, children's dietary intakes (3-day weighed food record) were recorded, body size was measured and blood samples were taken near their sixth birthday. SUBJECTS: A sample of 188 children, from two previous studies (cohorts 1 and 2), was contacted, and 139 (74%) agreed to participate. RESULTS: Multiple regression analyses with dietary and other factors showed that meat and fish consumption, multivitamin/mineral supplement intake (both positively) and cow's milk product consumption (negatively) were associated with log serum ferritin (SF) (adjusted R (2)=0.125; P=0.028; n=129), and juices and residence (rural>urban) with haemoglobin (Hb) (adjusted R (2)=0.085; P=0.034; n=127). Of 21 multivitamin/mineral consumers, none had depleted iron stores compared to 21 iron-depleted of 108 non-consumers (P=0.024). Children living in rural areas (10,000 inhabitants) (82.1+/-3.2 fl; n=103) (P=0.048). Multiple regression analyses with dietary and other factors and growth showed in cohort 1 that residence (rural>urban), weight gain 0-1years (negatively), and meat and fish intake (positively) were associated with Hb (adjusted R (2)=0.323; P=0.030; n=51), meat and fish (positively) with both log SF (adjusted R (2)=0.069; P=0.035; n=52) and MCV (adjusted R (2)=0.064; P=0.035; n=52), and in cohort 2 cow's milk product consumption (negatively) was associated with log SF (adjusted R (2)=0.119; P=0.017; n=41) and residence (rural>urban) with MCV (adjusted R (2)=0.102; P=0.025; n=41). CONCLUSIONS: Consumption of meat and fish and possibly also juices, as well as multivitamin/mineral intake might affect iron status in 6-year-old children positively, whereas cow's milk product consumption might affect iron status negatively. Slower growth in the first year of life and rural residence are positively related to iron status of 6-year-olds
The Regularizing Capacity of Metabolic Networks
Despite their topological complexity almost all functional properties of
metabolic networks can be derived from steady-state dynamics. Indeed, many
theoretical investigations (like flux-balance analysis) rely on extracting
function from steady states. This leads to the interesting question, how
metabolic networks avoid complex dynamics and maintain a steady-state behavior.
Here, we expose metabolic network topologies to binary dynamics generated by
simple local rules. We find that the networks' response is highly specific:
Complex dynamics are systematically reduced on metabolic networks compared to
randomized networks with identical degree sequences. Already small topological
modifications substantially enhance the capacity of a network to host complex
dynamic behavior and thus reduce its regularizing potential. This exceptionally
pronounced regularization of dynamics encoded in the topology may explain, why
steady-state behavior is ubiquitous in metabolism.Comment: 6 pages, 4 figure
Culture perfusion schedules influence the metabolic activity and granulocyte-macrophage colony-stimulating factor production rates of human bone marrow stromal cells
The metabolic function and GM-CSF production rates of adherent human bone marrow stromal cells were investigated as functions of medium and serum feeding rates. A range of medium exchange schedules was studied, ranging from a typical Dexter culture protocol of one weekly medium exchange to a full media exchange daily, which more closely approximates what bone marrow cells experience in situ. Glucose consumption was found to be significantly higher at full daily exchange rate than at any other exchange schedule examined. However, the lactate yield on glucose was a constant, at 1.8 mol/mol, under all conditions considered. Differential serum vs. medium exchange experiment showed that both serum supply and medium nutrients were responsible for the altered behavior at high exchange rates. Glutamine consumption was found to be insignificant under all culture conditions examined. A change in exchange schedule from 50% daily medium exchange to full daily medium exchange after 14 days of culture was found to result in a transient production of GM-CSF and a change in metabolic behavior to resemble that of cultures which had full daily exchange from day one. These results suggest that both stromal cell metabolism and GM-CSF production are sensitive to medium exchange schedules. Taken together, the data presented indicate that attempts to model the function of human bone marrow in vitro may be well served by beginning with medium exchange schedules that more closely mimic the in vivo physiologic state of bone marrow.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49880/1/1041470221_ftp.pd
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