| 84181. |
- Kumar Kalahasthi, Lokesh, 1988, et al.
(författare)
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Joint modeling of arrivals and parking durations for freight loading zones: Potential applications to improving urban logistics
- 2022
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Ingår i: Transportation Research Part a-Policy and Practice. - : Elsevier BV. - 0965-8564. ; 166, s. 307-329
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Tidskriftsartikel (refereegranskat)abstract
- This paper analyzes truck parking patterns in urban freight loading zones by jointly modeling the vehicle arrival rates and the parking durations. Three models were explored: 1) Count data (Negative Binomial) for vehicle arrivals, 2) Survival (Weibull) model for parking duration and 3) A joint model for arrivals and duration. The count data model estimates the parking demand i.e., the rate of truck arrival, while the survival model estimates the probability that a truck is parked for one more minute. The joint model is compared with separate models for predictability and performance. The dataset used in this research is obtained using a mobile phone parking appli-cation, at eight loading zones in the city Vic, Spain over an 18-month period from July 2018 to December 2019, comprised of vehicle parking durations, date, time of arrival and departure, professional activity, and vehicle type (weight). The parking activity data are complemented with built in environment variables of the loading zones, such as the number of establishments in a certain radius, the average walking distance to establishments, the presence of pedestrian pavement, the number of traffic lanes, among others. The joint model outperforms the models estimating the arrival rates and durations separately in goodness of fit and predictability. The model results showed that truck arrival rates vary significantly across days of the week, months, and arrival times. The parking durations are highly dependent on professional activity, vehicle type, and size. Tuesdays and Wednesdays have higher arrival rates compared to other days of a week (except Sundays). Among activities, the transport and parcels require longer parking du-rations. Among the vehicle types, trucks with gross weight larger than 3.5 tons park longer. This paper concludes by explaining the potential of these modeling approaches in improving urban freight operations, evaluation of various policy implications, limitations, and future research.
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| 84182. |
- Kumar, Manish, 1982, et al.
(författare)
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Gut microbiota dysbiosis is associated with malnutrition and reduced plasma amino acid levels: Lessons from genome-scale metabolic modeling
- 2018
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Ingår i: Metabolic Engineering. - : Elsevier BV. - 1096-7176 .- 1096-7184. ; 49, s. 128-142
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Tidskriftsartikel (refereegranskat)abstract
- Malnutrition is a severe non-communicable disease, which is prevalent in children from low-income countries. Recently, a number of metagenomics studies have illustrated associations between the altered gut microbiota and child malnutrition. However, these studies did not examine metabolic functions and interactions between individual species in the gut microbiota during health and malnutrition. Here, we applied genome-scale metabolic modeling to model the gut microbial species, which were selected from healthy and malnourished children from three countries. Our analysis showed reduced metabolite production capabilities in children from two lowincome countries compared with a high-income country. Additionally, the models were also used to predict the community-level metabolic potentials of gut microbes and the patterns of pairwise interactions among species. Hereby we found that due to bacterial interactions there may be reduced production of certain amino acids in malnourished children compared with healthy children from the same communities. To gain insight into alterations in the metabolism of malnourished (stunted) children, we also performed targeted plasma metabolic profiling in the first 2 years of life of 25 healthy and 25 stunted children. Plasma metabolic profiling further revealed that stunted children had reduced plasma levels of essential amino acids compared to healthy controls. Our analyses provide a framework for future efforts towards further characterization of gut microbial metabolic capabilities and their contribution to malnutrition.
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| 84183. |
- Kumar Maroju, Praveen, et al.
(författare)
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Attosecond pulse shaping using a seeded free-electron laser
- 2020
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 578, s. 386-391
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Tidskriftsartikel (refereegranskat)abstract
- Attosecond pulses are central to the investigation of valence- and core-electron dynamics on their natural timescales. The reproducible generation and characterization of attosecond waveforms has been demonstrated so far only through the process of high-order harmonic generation. Several methods for shaping attosecond waveforms have been proposed, including the use of metallic filters, multilayer mirrors and manipulation of the driving field. However, none of these approaches allows the flexible manipulation of the temporal characteristics of the attosecond waveforms, and they suffer from the low conversion efficiency of the high-order harmonic generation process. Free-electron lasers, by contrast, deliver femtosecond, extreme-ultraviolet and X-ray pulses with energies ranging from tens of microjoules to a few millijoules. Recent experiments have shown that they can generate subfemtosecond spikes, but with temporal characteristics that change shot-to-shot. Here we report reproducible generation of high-energy (microjoule level) attosecond waveforms using a seeded free-electron laser. We demonstrate amplitude and phase manipulation of the harmonic components of an attosecond pulse train in combination with an approach for its temporal reconstruction. The results presented here open the way to performing attosecond time-resolved experiments with free-electron lasers.
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| 84184. |
- Kumar, Nallani Vijay, et al.
(författare)
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Arsenic Directly Binds to and Activates the Yeast AP-1-Like Transcription Factor Yap8.
- 2016
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Ingår i: Molecular and cellular biology. - 1098-5549. ; 36:6, s. 913-22
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Tidskriftsartikel (refereegranskat)abstract
- The AP-1-like transcription factor Yap8 is critical for arsenic tolerance in the yeast Saccharomyces cerevisiae. However, the mechanism by which Yap8 senses the presence of arsenic and activates transcription of detoxification genes is unknown. Here we demonstrate that Yap8 directly binds to trivalent arsenite [As(III)] in vitro and in vivo and that approximately one As(III) molecule is bound per molecule of Yap8. As(III) is coordinated by three sulfur atoms in purified Yap8, and our genetic and biochemical data identify the cysteine residues that form the binding site as Cys132, Cys137, and Cys274. As(III) binding by Yap8 does not require an additional yeast protein, and Yap8 is regulated neither at the level of localization nor at the level of DNA binding. Instead, our data are consistent with a model in which a DNA-bound form of Yap8 acts directly as an As(III) sensor. Binding of As(III) to Yap8 triggers a conformational change that in turn brings about a transcriptional response. Thus, As(III) binding to Yap8 acts as a molecular switch that converts inactive Yap8 into an active transcriptional regulator. This is the first report to demonstrate how a eukaryotic protein couples arsenic sensing to transcriptional activation.
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| 84185. |
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| 84186. |
- Kumar, Rajat, et al.
(författare)
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Comparing Outcomes with Bone Marrow or Peripheral Blood Stem Cells as Graft Source for Matched Sibling Transplants in Severe Aplastic Anemia across Different Economic Regions.
- 2016
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Ingår i: Biology of blood and marrow transplantation : journal of the American Society for Blood and Marrow Transplantation. - : Elsevier BV. - 1523-6536. ; 22:5, s. 932-940
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Tidskriftsartikel (refereegranskat)abstract
- Bone marrow (BM) is the preferred graft source for hematopoietic stem cell transplantation (HSCT) in severe aplastic anemia (SAA) compared with mobilized peripheral blood stem cells (PBSCs). We hypothesized that this recommendation may not apply to those regions where patients present later in their disease course, with heavier transfusion load and with higher graft failure rates. Patients with SAA who received HSCT from an HLA-matched sibling donor from 1995 to 2009 and reported to the Center for International Blood and Marrow Transplant Research or the Japan Society for Hematopoietic Cell Transplantation were analyzed. The study population was categorized by gross national income per capita and region/countries into 4 groups. Groups analyzed were high-income countries (HIC), which were further divided into United States-Canada (n=486) and other HIC (n=1264); upper middle income (UMIC) (n=482); and combined lower-middle, low-income countries (LM-LIC) (n=142). In multivariate analysis, overall survival (OS) was highest with BM as graft source in HIC compared with PBSCs in all countries or BM in UMIC or LM-LIC (P<.001). There was no significant difference in OS between BM and PBSCs in UMIC (P=.32) or LM-LIC (P=.23). In LM-LIC the 28-day neutrophil engraftment was higher with PBSCs compared with BM (97% versus 77%, P<.001). Chronic graft-versus-host disease was significantly higher with PBSCs in all groups. Whereas BM should definitely be the preferred graft source for HLA-matched sibling HSCT in SAA, PBSCs may be an acceptable alternative in countries with limited resources when treating patients at high risk of graft failure and infective complications.
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| 84187. |
- Kumar, Rohini, et al.
(författare)
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Multiscale evaluation of the Standardized Precipitation Index as a groundwater drought indicator
- 2016
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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 20, s. 1117-1131
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Tidskriftsartikel (refereegranskat)abstract
- The lack of comprehensive groundwater observations at regional and global scales has promoted the use of alternative proxies and indices to quantify and predict groundwater droughts. Among them, the Standardized Precipitation Index (SPI) is commonly used to characterize droughts in different compartments of the hydro-meteorological system. In this study, we explore the suitability of the SPI to characterize local- and regional-scale groundwater droughts using observations at more than 2000 groundwater wells in geologically different areas in Germany and the Netherlands. A multiscale evaluation of the SPI is performed using the station data and their corresponding 0.5° gridded estimates to analyze the local and regional behavior of groundwater droughts, respectively. The standardized anomalies in the groundwater heads (SGI) were correlated against SPIs obtained using different accumulation periods. The accumulation periods to achieve maximum correlation exhibited high spatial variability (ranges 3–36 months) at both scales, leading to the conclusion that an a priori selection of the accumulation period (for computing the SPI) would result in inadequate characterization of groundwater droughts. The application of the uniform accumulation periods over the entire domain significantly reduced the correlation between the SPI and SGI (≈21–66%), indicating the limited applicability of the SPI as a proxy for groundwater droughts even at long accumulation times. Furthermore, the low scores of the hit rate (0.3–0.6) and a high false alarm ratio (0.4–0.7) at the majority of the wells and grid cells demonstrated the low reliability of groundwater drought predictions using the SPI. The findings of this study highlight the pitfalls of using the SPI as a groundwater drought indicator at both local and regional scales, and stress the need for more groundwater observations and accounting for regional hydrogeological characteristics in groundwater drought monitoring.
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| 84188. |
- Kumar, R. R., et al.
(författare)
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Effect of surfactant on functionalized multi-walled carbon nano tubes enhanced salt hydrate phase change material
- 2022
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Ingår i: Journal of Energy Storage. - : Elsevier BV. - 2352-152X. ; 55
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Tidskriftsartikel (refereegranskat)abstract
- Phase change materials (PCMs) are effective thermal energy storage materials; however, their low thermal conductivity nature tends to affect heat storage performance. Salt hydrate being inexpensive, incombustible and ensuring high phase change enthalpy, are highly attractive for energy storage. The potential of multi-walled carbon nanotubes (MWCNTs) in improving the thermophysical properties of salt hydrate PCMs makes it a hotspot of current research. Therefore, in this research article, MWCNTs and functionalized multi-walled carbon nanotubes (FMWCNTs) nanoparticles were dispersed with inorganic salt hydrate at different concentrations (0.3, 0.5, and 1.0 wt%), in the presence and absence of surfactant. The role of surfactant with salt hydrate PCM has been discussed extensively. The results obtained have ensured an enhancement in melting enthalpy of prepared composites by 4.92 %, and 28.5 % for 0.5 wt% MWCNT dispersed PCM (SHM0.5), and 0.5 wt% FMWCNT dispersed PCM (SHF0.5), respectively. Furthermore, the maximum thermal conductivity was enhanced by 50.0 % and 84.78 % for 0.5 wt% MWCNT dispersed PCM with surfactant (SHMS0.5), and SHF0.5 respectively, compared to salt hydrate PCM. From the improvement in thermal conductivity, light absorptance, thermal stability, latent heat, and chemical stability, it is evident that the prepared nanocomposite is a potential candidate for solar thermal energy storage applications.
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| 84189. |
- Kumar, Sonal, et al.
(författare)
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A Bi-based artificial interphase to achieve ultra-long cycling life of Al-metal anode in non-aqueous electrolyte
- 2024
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Ingår i: Energy Storage Materials. - 2405-8297. ; 65
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Tidskriftsartikel (refereegranskat)abstract
- Rechargeable aluminum-ion batteries (RAB) with Al-metal anode are regarded as cost-effective and environmentally sustainable energy storage systems. However, tapping the high volumetric capacity of the Al-anode has been a challenge because of the spontaneous and irreversible formation of the oxide layer on its surface that renders it electrochemically inactive. Though recently reported AlCl3-based electrolytes overcome this problem by breaking down this oxide layer, their highly corrosive nature hampers commercialization. Here, we investigate a novel approach to protect the Al-anode from severe oxidation by engineering an artificial protective interphase. A unique and less corrosive combination of Al(CF3SO3)3 salt and BiCl3 additive reacts with the Al-anode intrinsically to form an inorganic-rich protective bilayer. This layer is electronically insulating and significantly reduces the charge transfer resistance and surface activation energy at the anode, enabling plating/stripping at extremely low overpotential of <0.1 V that can be sustained for record-long cycling times of >4000 h.
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| 84190. |
- Kumar, Senthil, et al.
(författare)
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Abuse of peer review process by sham authors
- 2020
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Ingår i: European Science Editing. - : Pensoft Publishers. - 0258-3127 .- 2518-3354. ; 46
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This is a short letter on how the peer review process of many journals is being abused by some sham authors. While it would be difficult for the journals to identify and eliminate manuscripts that are not submitted with a sincere intention to publish, the universities and learning institutions should develop code of ethics to prevent their staff from abusing the journal review process. Imposing submission fee would also act as a deterrent against unscrupulous submissions.
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