• Considering that INPs affect the production of precipitation (enhancing or suppressing rainfall), cloud albedo, and cloud lifetime [ 33 ], advancing understanding of the mechanisms that influence INP abundance in the atmosphere is highly relevant to deciphering their contributions to cloud microphysical processes. (nature.com)
  • In silico modeling uses computational methods to simulate real biological processes in a virtual environment. (jax.org)
  • These data demonstrate the unique properties of DMT relative to other hallucinogens and underscore the differential regulation of the multiple processes mediating the effects of DMT. (erowid.org)
  • Genes make proteins that are involved in biological processes. (harvard.edu)
  • Despite expanding research, the etiology and underlying biological processes of autism remain poorly understood, and the relative contribution from genetic, epigenetic, and environmental factors remains unclear. (nih.gov)
  • Our findings suggest that M. aquifolium has anti-inflammatory and antioxidant effects that support the use in primary prevention of the inflammatory processes. (hindawi.com)
  • Its primary mission is to collect measurements of waves, currents, winds, tides, sand levels, and other phenomena in an effort to improve understanding of the processes that affect beaches. (whoi.edu)
  • Although scientists can learn a great deal from laboratory experiments, theoretical studies, and computer simulations, they need field measurements to test the results of these studies and to determine the relative importance of various processes on natural beaches. (whoi.edu)
  • BACKGROUND: Current studies examining the effects of high concentrations of red blood cell (RBC) or serum folates assume that high folate concentrations are an indicator of high folic acid intakes, often ignoring the contributions of other homeostatic and biological processes, such as kidney function. (cdc.gov)
  • Large-scale protein conformational motions on nanosecond-microsecond time scales are important for many biological processes, but remain largely unexplored because of methodological limitations. (lu.se)
  • When the genetic information containing the "blueprint" for these substances is disrupted, cell homeostasis is disrupted, resulting in a wide-range of immediate and/or delayed toxicological effects. (cdc.gov)
  • Direct and indirect ionization of DNA is ultimately responsible for the DNA alterations that adversely affect the structural and genetic integrity of the system. (cdc.gov)
  • environment modifies the genetic effects. (pikaia.eu)
  • Mood is affected by dozens of genes, and as our genetic endowments differ, so do our depressions. (harvard.edu)
  • reports of the National Research Council's committee on the Biological Effects of Ionizing Radiation. (cdc.gov)
  • The sievert takes into account the relative biological effectiveness (RBE) of ionizing radiation, since each form of such radiation-e.g. (veteranstoday.com)
  • The effects of radiation are radiation have concentrated on low- -particle with an energy of 2 MeV directly related to the dose received has an LET of about 180 keV/m. dose exposures, typical y of 0.1 Gy by individual cel s or organs, and All types of ionizing radiation in- (= 0.1 J/kg) and below. (who.int)
  • The nature of ionizing these effects can vary significant- fects, including DNA damage, chro- radiation ly, depending on the resulting dose mosomal aberrations, mutations, cell distribution or distribution of radionu- transformation, and cell killing (NRC, Ionizing radiation is a term used for clides throughout the body. (who.int)
  • The difference in maturity often contributes to the effect with age category, skill level and sport context also impacting the risk of the relative age effect. (wikipedia.org)
  • Developmental fitness curves: Assessing sprint acceleration relative to age and maturity status in elite junior tennis players. (academictree.org)
  • Repeated Sprint Ability in Youth Soccer Players: Independent and Combined Effects of Relative Age and Biological Maturity. (academictree.org)
  • Evidence of powerful individual differences in cognitive aging has sharpened focus on identifying biological factors underlying relative preservation versus vulnerability to decline. (jneurosci.org)
  • Functional analyses use stem cells and other biological systems in vitro . (jax.org)
  • This study explores the use of a simple human neurosphere-based in vitro model to characterise the pharmacological and toxicological effects of LiCl and VPA using gene expression changes linked to phenotypic alterations in cells. (plos.org)
  • The objectives of this study were to (1) link the binding mechanism of arsenic in soil (i.e., speciation) with in vitro bioaccessibility (IVBA) and in vivo methods used to predict relative bioavailability (RBA), and (2) to evaluate the permanence of bioavailability of lead in treated (i.e., remediated) soils. (serdp-estcp.org)
  • The extracts were assessed for Possible abortifacient effects by an in vitro method of testing for uterotonic activity. (who.int)
  • A very large radiation dose received in a short enough period of time to preclude significant repair can cause cellular walls to collapse and disrupt organ systems, producing deterministic effects such as acute radiation syndrome, cataracts, and teratogenesis (mental retardation, IQ reduction, microencephaly, stunted growth). (cdc.gov)
  • These effects can be caused by acute exposure to sources of high intensity radiation, such as can be found in hospitals, government, and industry. (cdc.gov)
  • The discussion below largely relates to lower radiation doses and dose rates which can cause non-deterministic effects and which are more relatable to radiation exposure from NPL sites. (cdc.gov)
  • hence, one of the concerns of IMRT is that, over time, this exposure of more tissue to low-dose radiation will cause a second malignancy or other unwanted late normal tissue effect. (nature.com)
  • However, successful treatment with heavy ions depends largely on knowledge of the relative biological effectiveness (RBE) of the radiation produced by primary and secondary charged particles. (edu.au)
  • Sparsely ionising radiation such as x-rays, electrons and gamma rays produce approximately equivalent biological effects for the same absorbed dose. (edu.au)
  • These are the recorded total Gamma Radiation and Sievert highs that affected people around the United States. (veteranstoday.com)
  • Effect of an optimized X-ray blanket design on operator radiation dose in cardiac catheterization based on real-world angiography. (uib.no)
  • The high blood cholesterol associated with FH leads to 50% of affected men having coronary disease by the age of 50, and 30% of women having coronary disease by the age of 60 years. (england.nhs.uk)
  • We use data on stock market participation of Swedish adoptees and relate this to the investment behavior of both their biological and adoptive parents. (lu.se)
  • To provide insight into this question, we take advantage of a unique feature of the Swedish adoption system whereby we observe both the biological and adoptive parents of adopted children. (lu.se)
  • We use administrative data on the portfolio choices of a large sample of adopted children born between 1950 and 1980 merged with similar information for their biological and adoptive parents--as well as corresponding data on own-birth children. (lu.se)
  • biological and adoptive parents. (lu.se)
  • Theiler's disease) is a serious and often life-threatening disease of unknown etiology that affects horses. (cdc.gov)
  • However, heavy ions produce different biological effects for the same absorbed dose. (edu.au)
  • Spatial agreement of brainstem dose distributions depending on biological model in proton therapy for pediatric brain tumors. (uib.no)
  • Biological dose and complication probabilities for the rectum and bladder based on linear energy transfer distributions in spot scanning proton therapy of prostate cancer. (uib.no)
  • A phenomenological biological dose model for proton therapy based on linear energy transfer spectra. (uib.no)
  • For example, comment on the shape of the dose- traversing, producing chemical and cobalt-60 -rays have an LET of response curve and the associated biological damage. (who.int)
  • causation would translate into protection and the most applicable of these characteristics would be biological plausibility, consistency, and biological gradient (ie, dose-response relationship). (msdmanuals.com)
  • The presence of a biological gradient, or dose response, strengthens the inference of causality in an observational trial because, at least up to a point, the magnitude of an outcome associated with exposure to a truly causative environmental factor increases with the magnitude of the exposure. (msdmanuals.com)
  • All of these mechanisms negatively affect expression of the gene. (jax.org)
  • lt;p>Nuisance levels of benthic algae are becoming increasingly common in surface waters of the western United States and can compromise aesthetic quality, limit recreational activities, block water infrastructure, and negatively affect aquatic life. (usgs.gov)
  • Objective To evaluate the effect of vitamin E supplementation on incident total, ischaemic, and haemorrhagic stroke. (bmj.com)
  • With these methods, near-infrared energy is primarily absorbed in the superficial tissues, thus these approaches are unable to sufficiently evaluate the biological effects of solar near-infrared that reaches human tissue. (scirp.org)
  • A linear mixed-effects model was used to evaluate the relative effect of different factors on algal biomass across water-quality sites. (usgs.gov)
  • Reliable assessment of oxidative stress by measuring MDA, HNE and 15(S)-8-iso-PGF2α in biological fluids is highly challenging for two important reasons: Because of the duality of oxidative stress, i.e., its origin from chemical and enzymatic reactions, and because of pre-analytical and analytical issues. (scienceopen.com)
  • The compatibility of Alisma and Atractylodes (AA) has been estimated to exhibit antiatherosclerotic effects, but the mechanism remains unclear. (hindawi.com)
  • Glycosaminoglycans (GAGs), known to be present in airway mucus, are macromolecules with a variety of structural and biological functions. (nih.gov)
  • The efficiency sential y uniform after whole-body izing (i.e. removing electrons from) in causing damage and subsequent exposure to being highly heteroge- atoms or molecules of the medium biological effects is related not only neous in the case of non-uniform to the amount of energy transferred being traversed. (who.int)
  • millisecond range, can be detected via their effects on the The relative positions of protein atoms undergo thermal fluctua- isotropic chemical shift.3 But this still leaves a significant time tions under the influence of interactions within the protein and scale gap, 10-8-10-5 s, that cannot be probed directly by with the solvent. (lu.se)
  • The extract of Alisma orientale exerted a protective effect on nonalcoholic fatty liver disease and palmitate-induced cellular injury [ 21 , 22 ], suggesting that it could be a potential treatment for abnormal lipid metabolism syndrome. (hindawi.com)
  • citation needed] Relative age effects are caused by birth date eligibility rules but can be affected by parents, coaches and athletes through other mechanisms, the Pygmalian effect, Galatea effect, and Matthew effect are examples of effects which impact player motivation. (wikipedia.org)
  • Despite the varied roles of bioaerosols in environmental health, biological dispersion, and the land-atmosphere system, their ecological sources and emission mechanisms remain poorly understood [ 13 ]. (nature.com)
  • Over half of solar energy consists of near-infrared and a wide range of preventative mechanisms have been evolutionarily maintained in organisms to protect against effects of near-infrared. (scirp.org)
  • Although autism affects primarily brain function (especially affect, social functioning, and cognition), it is unknown to what extent other organs and systems are disrupted. (nih.gov)
  • Trio ES in families affected by autism cost $3,054 compared to $4,917 for trio WGS. (cdc.gov)
  • When compared to air sampled prior to ignition, samples of the air-smoke mixtures contained fivefold higher concentrations of microbial cells (6.7 ± 1.3 × 10 4 cells m −3 ) and biological INPs (2.4 ± 0.91 × 10 3 INPs m −3 active at temperatures ≥ −15 °C), and these data significantly positively correlated with PM 10 . (nature.com)
  • Vitamin E had no effect on the risk for total stroke (pooled relative risk 0.98 (95% confidence interval 0.91 to 1.05), P=0.53). (bmj.com)
  • It has been reported that Alisma orientale has a protective effect on acute lung injury through an anti-inflammatory effect by repressing the NF-kappa B pathway [ 20 ]. (hindawi.com)
  • The in vivo antioxidant effects and the anti-inflammatory potential were tested on a rat turpentine oil-induced inflammation, by measuring serum nitric oxide (NOx) and TNF-alpha, total oxidative status (TOS), total antioxidant reactivity (TAR), oxidative stress index (OSI), 3-nitrothyrosine (3NT), malondialdehyde (MDA), and total thiols (SH). (hindawi.com)
  • These numbers don't apply to fraternal twins, who - like other biological siblings - share only about half of their genes. (harvard.edu)
  • Contrast with inundative biological control]. (ufl.edu)
  • In contrast, the risk for haemorrhagic stroke was increased (pooled relative risk 1.22 (1.00 to 1.48), P=0.045), while the risk of ischaemic stroke was reduced (pooled relative risk 0.90 (0.82 to 0.99), P=0.02). (bmj.com)
  • By contrast, the relative effect of soil moisture varied dramatically among genotypes, from 8-fold more DETs due to parental than immediate conditions to 10-fold fewer. (lu.se)
  • 50% protein identity with its phylogenetic relatives of the genus Copiparvovirus . (cdc.gov)
  • The predicted effects of a variant on functional areas of the protein such as binding sites for DNA or other proteins can also be analyzed. (jax.org)
  • The problem of protein energy malnutrition that affects millions of children in the world is firmly rooted in the cultural pattern, dietary habits and the general soci.o-economic condition of the people. (who.int)
  • Predicting the concentrated solution behaviour requires understanding how to map protein-protein interactions on simplified models, which account for the relative contributions from repulsive and attractive forces, shape and interaction anisotropy, and any effects due to intra-molecular flexibility. (lu.se)
  • The relative contributions remain under debate. (pikaia.eu)
  • OBJECTIVE: The current study examined the relative contributions of declining kidney function, as measured by the risk of chronic kidney disease (CKD), and usual total folic acid intake on the concentrations of RBC folate and serum folate (total as well as individual folate forms). (cdc.gov)
  • To assess correlations between biological and environmental data, Spearman rank correlation coefficients were calculated. (cdc.gov)
  • Weltz, Newingham) Subobjective 1C: Investigate effects of post-expansion piñon and juniper tree control and exclusionary fencing on components of the water budget and recovery of sagebrush steppe and meadow habitats and assess weather variability and impacts on plant phenology. (usda.gov)
  • NP215 1A, 3B, 4A) Subobjective 2A: Assess effects of post-fire grazing on burned rangelands. (usda.gov)
  • Ecological and hydrological instrumentation will be used at a field station in central Nevada to: (1) investigate effects of post-expansion piñon and juniper tree control and exclusionary fencing on components of the water budget and recovery of natural habitats, and (2) assess weather variability and impacts on plant phenology. (usda.gov)
  • Aim: The aim of this study was to assess prospectively the independent effects of occupational physical activity (OPA) and conditioning leisure time physical activity (LTPA) on atherosclerosis, coronary heart disease (CHD) and mortality among 1861 working middle-aged Finnish men with and without CHD at baseline. (cdc.gov)
  • Interaction effects were determined followed by analyses stratified by baseline CHD. (cdc.gov)
  • A number of large, randomised, placebo controlled trials 7 8 9 10 11 12 13 14 and two meta-analyses 15 16 investigated the effects of vitamin E on incident cardiovascular disease. (bmj.com)
  • Transcriptomic analyses showed that the relative effects of parent and offspring environment on gene expression (i.e. the number of differentially expressed transcripts, DETs) varied both for the two types of resource stress and among genotypes. (lu.se)
  • In cooperation with the White River and Douglas Creek Conservation Districts, the Colorado River Basin Salinity Control Forum, and the Colorado River Water Conservation District, the U.S. Geological Survey studied physical, chemical, and biological factors potentially controlling the occurrence of benthic algae in the upper White River Basin, Colorado, from 2018 through 2021. (usgs.gov)
  • An in vivo method was utilized in order to determine any anti-implantation, early abortifacient and/or foetal resorption effects of these extracts. (who.int)
  • Native proteins adopt unique three-dimensional structures, slower motions, from tens of microseconds and into the but their biological functions usually rely on structural flexibility. (lu.se)
  • However, these drugs have potential developmental effects that are not fully understood. (plos.org)
  • These findings provide evidence at the transcriptomic level that the relative impacts of parental and immediate environment on the developing organism may depend on the environmental factor and vary strongly among genotypes, providing potential for the interplay of these developmental influences to evolve. (lu.se)
  • It reviews reported analytical methods and their principles for the quantitative measurement of MDA, HNE and 15(S)-8-iso-PGF2α in biological samples including plasma and urine, and critically discusses their biological and biomedical outcome which is rarely crystal clear and free of artefacts. (scienceopen.com)
  • Data from observational studies support this view, suggesting a protective effect against coronary heart disease. (bmj.com)
  • Subsequently, risk and protective factors across life have a cumulative effect on health trajectories. (who.int)
  • And finally, family studies, which examine whether a variant tracking with affected relatives is statistically significant. (jax.org)
  • In this paper we will examine the effects of the repeated electromagnetic field stimulation (REMFS) on cell cultures, mouse models, and computer simulations for diagnostic purposes. (intechopen.com)
  • The spearman correlation analysis revealed that UPF supplementation reduced the relative abundance of Parasutterella and possibly decreased the blood sugar levels, leading to a decrease in the relative abundances of Blautia and Fusicatenibacter and a subsequent decrease in insulin levels. (frontiersin.org)
  • The carcinogenic risk associated their energy to biological material in tion risk estimates. (who.int)
  • Various methods have been suggested and tested to reduce the relative age effect like moving the cut off dates, expanding the age group range, birthdate quotas for the players, the average team age (ATA) method for eligibility, or grouping by height and weight. (wikipedia.org)
  • Some methods have struggled to find success due to the effect moving with selection dates. (wikipedia.org)
  • Study results show that 5 IVBA methods were predictive of the relative bioavailability of arsenic in 27 contaminated soils and solid wastes indicating that IVBA methods provide reliable data for use by DoD site managers. (serdp-estcp.org)
  • Methods: Fitness (VO2max), OPA (work posture, energy expenditure, relative aerobic workload), conditioning LTPA, cardiovascular disease (CVD) status and potential confounders were assessed at baseline. (cdc.gov)
  • Furthermore, analytical methods need to be paired with practical preanalytical conditions that allow for the collection and generation of valid biological specimens. (cdc.gov)
  • Aging is accompanied by profound changes in the brain's dopamine system that affect cognitive function. (jneurosci.org)
  • We found clear evidence in young adults that low levels of synthesis capacity were suboptimal, associated with diminished cognitive flexibility and altered frontoparietal activation relative to young adults with highest synthesis values. (jneurosci.org)
  • In addition to these social factors contextual differences change the distribution with decreased effects in female sports, unpopular sports, at different ages, individual sports or sports with a lower reliance on body size with an expected increased effect in male sports, popular sports, or competitive sports. (wikipedia.org)
  • Relative hazards with 95% confidence intervals were estimated in Cox regression models incrementally adjusting for 18 demographic, biological, behavioural, socioeconomic and psychosocial factors. (cdc.gov)
  • Without streambed disturbance, other factors such as nutrients and water temperature may have a larger effect on algal biomass. (usgs.gov)
  • The authors adjusted for all of these factors and found that, on the relative scale, lonely people were still about 20%-30% more likely to develop Parkinson's disease. (medscape.com)
  • A questionnaire was used for the dietary survey Data thus obtained revealed the widespread prevalence of malnutrition among children the target population and allowed examination of the relationships between the various factors affecting the nutritional status of the children. (who.int)
  • For example, you may be dealing with a difficult situation, such as trying to manage a chronic illness, taking care of an ill relative, or facing money problems. (medlineplus.gov)
  • When one also considers the indirect effects of caffeine and the possibility of effects of other active ingredients in coffee, it quickly becomes evident that prediction of the effects of habitual coffee ingestion on the propensity to tachyarrhythmias, in the general population or in a specific individual, is not possible. (msdmanuals.com)
  • The indirect effects are the additional consequences caused by the hazard over time that can harm health, like unsafe or unhealthy living conditions, lost livelihoods, displacement, and damages to infrastructure like clean water supplies. (who.int)
  • Moreover, UPF supplementation had a positive impact on gut microbiota, decreasing the relative abundances of Blautia, Parasutterella and Fusicatenibacter which were closely related to obesity, and increasing the relative abundances of probiotics ( Allobaculum, Romboutsia, Staphylococcus , and Bacteroides ). (frontiersin.org)
  • The results were largely disappointing, and no overall effect of vitamin E on main composite end points, including myocardial infarction, total stroke, or death due to cardiovascular disease, were found. (bmj.com)
  • VUS, where the effect of the variant on gene function is unknown. (jax.org)
  • A variant form of classical biological control uses biological control agents imported from a third area, inhabited by a close relative of the target pest. (ufl.edu)
  • They were inserting false holograms to create the causality for their desired effects in the timelines, and then reaping the rewards of others hard work and consciousness energy. (energeticsynthesis.com)
  • Playing position, federation membership, and individual and team performance also contribute to the effect with older players having a higher risk of injury. (wikipedia.org)
  • See also risk , relative risk . (cdc.gov)
  • A person who has a first-degree relative who suffered major depression has an increase in risk for the condition of 1.5% to 3% over normal. (harvard.edu)
  • Among men without CHD, each 10% increase of relative aerobic workload increased AMI risk by 18% (hazard ratio (HR) 1.18, 95% confidence interval (CI) 1.08-1.28, P¼0.001), all-cause mortality by 15% (HR 1.15, 95% CI 1.07-1.24, P¼0.000) and CHD mortality by 30% (HR 1.30, 95% CI 1.14-1.49, P¼0.000). (cdc.gov)
  • As such, early diagnosis and treatment of FH is crucial, particularly as effective treatment can reduce an affected individual's lifetime cardiovascular risk to that of someone unaffected. (england.nhs.uk)
  • The importance of these characteristics and how they translate to risk is relative to the population exposed to the hazard. (who.int)
  • However, once we condition on having positive financial wealth, we find that nurture has a much stronger influence on risk-taking by children, and the evidence of a relationship between stock-holding of biological parents and their adoptive children becomes weaker. (lu.se)
  • These data suggest that, in diseases where the contribution to secretions of glands versus epithelial cells is altered, the relative concentration of individual GAGs, and therefore their biological activities, will also be affected. (nih.gov)
  • These alterations can result in the wide range of somatic and reproductive effects described in greater detail in Chapter 3. (cdc.gov)
  • Alterations in these pathways can affect function in both systems. (nih.gov)
  • A living organism applied as an inundative biological control agent or augmentative biological control agent. (ufl.edu)
  • Mental disorders are serious conditions which can affect your thinking, mood, and behavior. (medlineplus.gov)
  • We have previously utilised an NT2.D1 neurosphere based model of neuronal differentiation to study the effects of a variety of compounds on neural development [7] . (plos.org)
  • Using the PET tracer 6-[ 18 F]fluoro- l - m -tyrosine, we found strong support for upregulated striatal dopamine synthesis capacity in healthy older adult humans free of amyloid pathology, relative to young people. (jneurosci.org)
  • The Organ Sparing Potential of Different Biological Optimization Strategies in Proton Therapy. (uib.no)
  • An important part of our research is to understand the relative merits of different strategies to integrate conservation with agricultural and silvicultural production in terms of conservation goals, ecosystem service flows and resilience in a rapidly changing world. (lu.se)
  • The direct effects of caffeine on arrhythmogenesis are complex with both potentially arrhythmic effects (including sympathetic activation) and potentially antiarrhythmic effects (including adenosine receptor blockade and antioxidant properties). (msdmanuals.com)
  • Eating disorders are a challenging and disturbing multifaceted problem with biological, psychological and cultural roots. (nextavenue.org)
  • Their foster parents seek to adopt them, with the consent of the boys' biological parents. (narf.org)
  • they, too, have filed an adoption petition, without the consent of the boys' biological parents. (narf.org)
  • When conducting sequencing in children, it's useful to sequence both biological parents at the same time as the child-a trio sequence. (cdc.gov)
  • This study aimed to identify the role of AA in oxidized low-density lipoprotein (ox-LDL)-induced vascular smooth muscle cell (VSMC) behaviours and to explore the effects of microRNAs (miRNAs). (hindawi.com)
  • In this study we analyzed microbial cells and biological ice nucleating particles (INPs) in smoke emitted from eight prescribed wildland fires in North Florida. (nature.com)
  • The objectives of this study were to determine if wildland fire smoke is an atmospheric source of viable microbes and biological INPs and estimate the scale of their emissions. (nature.com)
  • In this study we treated differentiating NT2.D1 neurospheres with LiCl or VPA in order to determine their effects using a toxicogenomic and phenotypic anchoring approach. (plos.org)
  • This study aims to form physical fitness reference standards based on the relative age and gender variables of Turkish female and male children between the ages of 7 and 13. (thesportjournal.org)
  • This study formed percentile norm tables that had values ranging between 5 and 95 by using the anthropometric and physical fitness test results obtained based on the standard values related to gender and relative age of Turkish children between the ages of 7 and 13. (thesportjournal.org)
  • 2 Relative to the study of Kim et al. (msdmanuals.com)
  • Pooled effect estimates were then calculated. (bmj.com)
  • and (b) to determine the relative importance of maladaptive personality facets in the statistical prediction of stalking. (bvsalud.org)
  • This in turn, could result in the loss of populations and seriously affect the shore communities of which they are part. (gov.scot)
  • Populations must be exposed to a hazard, either directly or indirectly, to be affected by it. (who.int)
  • We emphasize the fruitful combination of basic and applied research, to understand the effect of agriculture and forestry on the persistence of populations and the generation of ecosystem services such as pollination, biological control and carbon sequestration. (lu.se)
  • Environmental samples were collected from these 18 homes, and biological samples were collected from 78 residents of these homes. (cdc.gov)
  • The environmental drivers affecting one domain are also easily reflected in other domains. (copernicus.org)
  • They can affect your ability to relate to others and function each day. (medlineplus.gov)