| 2931. |
|
|
| 2932. |
- Shrivastava, Manish, et al.
(författare)
-
Recent advances in understanding secondary organic aerosol : Implications for global climate forcing
- 2017
-
Ingår i: Reviews of Geophysics. - 8755-1209. ; 55:2, s. 509-559
-
Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic emissions and land use changes have modified atmospheric aerosol concentrations and size distributions over time. Understanding preindustrial conditions and changes in organic aerosol due to anthropogenic activities is important because these features (1) influence estimates of aerosol radiative forcing and (2) can confound estimates of the historical response of climate to increases in greenhouse gases. Secondary organic aerosol (SOA), formed in the atmosphere by oxidation of organic gases, represents a major fraction of global submicron-sized atmospheric organic aerosol. Over the past decade, significant advances in understanding SOA properties and formation mechanisms have occurred through measurements, yet current climate models typically do not comprehensively include all important processes. This review summarizes some of the important developments during the past decade in understanding SOA formation. We highlight the importance of some processes that influence the growth of SOA particles to sizes relevant for clouds and radiative forcing, including formation of extremely low volatility organics in the gas phase, acid-catalyzed multiphase chemistry of isoprene epoxydiols, particle-phase oligomerization, and physical properties such as volatility and viscosity. Several SOA processes highlighted in this review are complex and interdependent and have nonlinear effects on the properties, formation, and evolution of SOA. Current global models neglect this complexity and nonlinearity and thus are less likely to accurately predict the climate forcing of SOA and project future climate sensitivity to greenhouse gases. Efforts are also needed to rank the most influential processes and nonlinear process-related interactions, so that these processes can be accurately represented in atmospheric chemistry-climate models.
|
|
| 2933. |
- Siewers, Verena, 1976, et al.
(författare)
-
Heterologous production of non-ribosomal peptide LLD-ACV in Saccharomyces cerevisiae
- 2009
-
Ingår i: Metabolic Engineering. - : Elsevier BV. - 1096-7176 .- 1096-7184. ; 11:6, s. 391-397
-
Tidskriftsartikel (refereegranskat)abstract
- Non-ribosomal peptides (NRPs) are a diverse family of secondary metabolites with a broad range of biological activities. We started to develop an eukaryotic microbial platform based on the yeast Saccharomyces cerevisiae for heterologous production of NRPs using delta-(L-alpha-aminoadipyl)-L-cysteinyl-D- valine (ACV) as a model NRP. The Penicillium chrysogenum gene pcbAB encoding ACV synthetase was expressed in S. cerevisiae from a high-copy plasmid together with phosphopantetheinyl transferase (PPTase) encoding genes from Aspergillus nidulans, P. chrysogenum and Bacillus subtilis, and in all the three cases production of ACV was observed. To improve ACV synthesis, several factors were investigated. Codon optimization of the 50 end of pcbAB did not significantly increase ACV production. However, a 30-fold enhancement was achieved by lowering the cultivation temperature from 30 to 20 degrees C. When ACVS and PPT a seen coding genes were integrated into the yeast genome, a 6-fold decrease in ACV production was observed indicating that gene copy number was one of the rate-limiting factors for ACV production in yeast. (C) 2009 Elsevier Inc. All rights reserved.
|
|
| 2934. |
- Silventoinen, K., et al.
(författare)
-
Educational attainment of same-sex and opposite-sex dizygotic twins : An individual-level pooled study of 19 twin cohorts
- 2021
-
Ingår i: Hormones and Behavior. - : Elsevier. - 0018-506X .- 1095-6867. ; 136
-
Tidskriftsartikel (refereegranskat)abstract
- Comparing twins from same- and opposite-sex pairs can provide information on potential sex differences in a variety of outcomes, including socioeconomic-related outcomes such as educational attainment. It has been suggested that this design can be applied to examine the putative role of intrauterine exposure to testosterone for educational attainment, but the evidence is still disputed. Thus, we established an international database of twin data from 11 countries with 88,290 individual dizygotic twins born over 100 years and tested for differences between twins from same- and opposite-sex dizygotic pairs in educational attainment. Effect sizes with 95% confidence intervals (CI) were estimated by linear regression models after adjusting for birth year and twin study cohort. In contrast to the hypothesis, no difference was found in women (β = −0.05 educational years, 95% CI −0.11, 0.02). However, men with a same-sex co-twin were slightly more educated than men having an opposite-sex co-twin (β = 0.14 educational years, 95% CI 0.07, 0.21). No consistent differences in effect sizes were found between individual twin study cohorts representing Europe, the USA, and Australia or over the cohorts born during the 20th century, during which period the sex differences in education reversed favoring women in the latest birth cohorts. Further, no interaction was found with maternal or paternal education. Our results contradict the hypothesis that there would be differences in the intrauterine testosterone levels between same-sex and opposite-sex female twins affecting education. Our findings in men may point to social dynamics within same-sex twin pairs that may benefit men in their educational careers.
|
|
| 2935. |
- Singer, A., et al.
(författare)
-
Post-operative electrode placement prediction in deep brain stimulation using support vector regression
- 2019
-
Ingår i: Proceedings of the Third International Symposium on Image Computing and Digital Medicine, ISICDM 2019. - New York, NY, USA : Association for Computing Machinery. - 9781450372626 ; , s. 202-207
-
Konferensbidrag (refereegranskat)abstract
- Deep brain stimulation (DBS) is a neurosurgical procedure for treating neurodegenerative diseases and neurological disorders such as Parkinson’s disease (PD) and epilepsy. Image guidance is crucial for the accurate placement of DBS electrodes. However, current surgical planning systems based on preoperative MR and CT images of the brain cannot take into account the intra-operative brain-shift, resulting in suboptimal electrode placement undermining clinical outcomes. In this study, a support vector regression (SVR) model was constructed based on 114 patient-specific data of PD patients. Two target nuclei were manually delineated based on pre-operative MR and CT images. Spatial coordinates of the two nuclei were collected and compared to the post-surgical electrode position from CT images. Analysis of a total of 45 features showed that the pre-operative target coordinates are the parameters mainly influencing the model prediction for both nuclei. The mean absolute error (MAE) of the prediction of the electrodes on unseen patients was 0.76mm. This study demonstrates the potential of using SVR modelling to improve current DBS surgical planning procedure and preoperative risk-assessment.
|
|
| 2936. |
- Sintes, J, et al.
(författare)
-
mTOR intersects antibody-inducing signals from TACI in marginal zone B cells
- 2017
-
Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8:1, s. 1462-
-
Tidskriftsartikel (refereegranskat)abstract
- Mechanistic target of rapamycin (mTOR) enhances immunity in addition to orchestrating metabolism. Here we show that mTOR coordinates immunometabolic reconfiguration of marginal zone (MZ) B cells, a pre-activated lymphocyte subset that mounts antibody responses to T-cell-independent antigens through a Toll-like receptor (TLR)-amplified pathway involving transmembrane activator and CAML interactor (TACI). This receptor interacts with mTOR via the TLR adapter MyD88. The resulting mTOR activation instigates MZ B-cell proliferation, immunoglobulin G (IgG) class switching, and plasmablast differentiation through a rapamycin-sensitive pathway that integrates metabolic and antibody-inducing transcription programs, including NF-κB. Disruption of TACI–mTOR interaction by rapamycin, truncation of the MyD88-binding domain of TACI, or B-cell-conditional mTOR deficiency interrupts TACI signaling via NF-κB and cooperation with TLRs, thereby hampering IgG production to T-cell-independent antigens but not B-cell survival. Thus, mTOR drives innate-like antibody responses by linking proximal TACI signaling events with distal immunometabolic transcription programs.
|
|
| 2937. |
|
|
| 2938. |
- Sloboda, Tamara, et al.
(författare)
-
A method for studying pico to microsecond time-resolved core-level spectroscopy used to investigate electron dynamics in quantum dots
- 2020
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- Time-resolved photoelectron spectroscopy can give insights into carrier dynamics and offers the possibility of element and site-specific information through the measurements of core levels. In this paper, we demonstrate that this method can access electrons dynamics in PbS quantum dots over a wide time window spanning from pico- to microseconds in a single experiment carried out at the synchrotron facility BESSY II. The method is sensitive to small changes in core level positions. Fast measurements at low pump fluences are enabled by the use of a pump laser at a lower repetition frequency than the repetition frequency of the X-ray pulses used to probe the core level electrons: Through the use of a time-resolved spectrometer, time-dependent analysis of data from all synchrotron pulses is possible. Furthermore, by picosecond control of the pump laser arrival at the sample relative to the X-ray pulses, a time-resolution limited only by the length of the X-ray pulses is achieved. Using this method, we studied the charge dynamics in thin film samples of PbS quantum dots on n-type MgZnO substrates through time-resolved measurements of the Pb 5d core level. We found a time-resolved core level shift, which we could assign to electron injection and charge accumulation at the MgZnO/PbS quantum dots interface. This assignment was confirmed through the measurement of PbS films with different thicknesses. Our results therefore give insight into the magnitude of the photovoltage generated specifically at the MgZnO/PbS interface and into the timescale of charge transport and electron injection, as well as into the timescale of charge recombination at this interface. It is a unique feature of our method that the timescale of both these processes can be accessed in a single experiment and investigated for a specific interface.
|
|
| 2939. |
|
|
| 2940. |
- Smith-Warner, Stephanie A., et al.
(författare)
-
Methods for pooling results of epidemiologic studies - The pooling project of prospective studies of diet and cancer
- 2006
-
Ingår i: American Journal of Epidemiology. - Harvard Univ, Sch Publ Hlth, Dept Nutr, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Epidemiol, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Biostat, Boston, MA 02115 USA. NCI, Nutr Epidemiol Branch, Bethesda, MD USA. Loma Linda Univ, Sch Med, Ctr Hlth Res, Loma Linda, CA 92350 USA. Univ So Calif, Dept Prevent Med, Los Angeles, CA USA. Univ So Calif, Norris Comprehens Canc Ctr, Los Angeles, CA USA. NCI, Epidemiol Unit, Milan, Italy. Maastricht Univ, Fac Hlth Sci, Dept Epidemiol, Maastricht, Netherlands. Brigham & Womens Hosp, Dept Med, Div Prevent Med, Boston, MA USA. Harvard Univ, Sch Med, Boston, MA USA. Brigham & Womens Hosp, Dept Med, Channing Lab, Boston, MA USA. Brigham & Womens Hosp, Dept Med, Channing Lab, Boston, MA 02115 USA. Harvard Univ, Ctr Canc Prevent, Boston, MA USA. Univ Minnesota, Sch Publ Hlth, Div Epidemiol & Community Hlth, Minneapolis, MN USA. SUNY Buffalo, Dept Social & Prevent Med, Buffalo, NY USA. TNO Qual Life, Dept Epidemiol, Zeist, Netherlands. No Calif Canc Ctr, Fremont, CA USA. NCI, Div Canc Epidemiol & Genet, Bethesda, MD USA. Amer Canc Soc, Epidemiol & Surveilliance Res, Atlanta, GA USA. Univ Toronto, Fac Med, Dept Publ Hlth Sci, Toronto, ON, Canada. Albert Einstein Coll Med, Dept Epidemiol & Populat Hlth, Bronx, NY USA. NYU, Sch Med, Dept Environm Med, New York, NY USA. Natl Publ Hlth Inst, Dept Epidemiol & Hlth Promot, Helsinki, Finland. Natl Inst Environm Med, Div Nutr Epidemiol, Stockholm, Sweden. : OXFORD UNIV PRESS INC. - 0002-9262 .- 1476-6256. ; 163:11, s. 1053-1064
-
Tidskriftsartikel (refereegranskat)abstract
- With the growing number of epidemiologic publications on the relation between dietary factors and cancer risk, pooled analyses that summarize results from multiple studies are becoming more common. Here, the authors describe the methods being used to summarize data on diet-cancer associations within the ongoing Pooling Project of Prospective Studies of Diet and Cancer, begun in 1991. In the Pooling Project, the primary data from prospective cohort studies meeting prespecified inclusion criteria are analyzed using standardized criteria for modeling of exposure, confounding, and outcome variables. In addition to evaluating main exposure-disease associations, analyses are also conducted to evaluate whether exposure-disease associations are modified by other dietary and nondietary factors or vary among population subgroups or particular cancer subtypes. Study-specific relative risks are calculated using the Cox proportional hazards model and then pooled using a random- or mixed-effects model. The study-specific estimates are weighted by the inverse of their variances in forming summary estimates. Most of the methods used in the Pooling Project may be adapted for examining associations with dietary and nondietary factors in pooled analyses of case-control studies or case-control and cohort studies combined.
|
|
