3,158 research outputs found
Thriving on Mars: Potatoes as the Answer to Martian Challenges
Humans have committed themselves to the exploration of space and the quest for a habitable planet. Central to the development of a sustainable ecosystem that can provide essential resources like food and water is the implementation of space plant cultivation systems. In the pursuit of bio-regenerative life support systems for human space exploration, the inclusion of plants is imperative. This study focuses on assessing potential challenges associated with cultivating Potatoes (Solanum tuberosum) under simulated Martian conditions. Potatoes exhibit adaptability to extremely cold and dry environments, making them a promising candidate for extraterrestrial agriculture. The advantages of potatoes include their high yield, rich content of easily digestible carbohydrates, elevated protein levels, and simplicity of propagation. When induced to tuberize, potatoes can achieve a harvest index exceeding 80%, approximately double that of traditional grain crops. Notably, unlike certain crops such as soybeans and certain grains, potatoes do not necessitate elaborate processing procedures before consumption. The Potato, specifically varieties like Norland, Denali, and Russet Burbank, has garnered attention in research funded by the US National Aeronautics and Space Administration (NASA). Tests have revealed that these cultivars can successfully undergo tuberization even under constant bright light conditions, emphasizing their potential suitability for life support functions in space exploration context
Exploring Frontiers: Interdisciplinary Insights into Human Space Flight Advancements
This review article comprehensively examines the multifaceted landscape of human space flight, focusing on the transformative role of the International Space Station (ISS) and the evolving challenges and opportunities associated with deep space exploration. Anchored in the synergy between space science, engineering, and human physiology, our exploration unfolds across key domains, shedding light on the scientific, technological, and psychological dimensions of human space missions
Multidrug resistant Salmonella species isolated from fufu grinding machines in Ghana
Multidrug resistant Salmonella infection has become one of the most dangerous health concerns in Sub-Saharan Africa. Most previous research shows that food and water are the sources of the human Salmonella infection in Ghana. This article examines Salmonella contamination of fufu, a thick paste prepared from pounded boiled tubers, traditionally prepared using pestle and mortar, a common food in West and Central Africa. The fufu grinding machine, a new technology for grinding fufu, is gaining root in many parts of Sub-Saharan Africa, particularly in the urban areas where most people are inclined to use machines to minimize drudgery, leaving behind the traditional way which involves the use of a wooden mortar and pestle. To investigate the sources of these contaminations, 100 samples were collected from 50 randomly sampled fufu grinding machines in the Tamale Metropolis to examine the prevalence and antibiotic susceptibility of Salmonella species. Fufu samples (SA) and fufu wash-out samples (SB) were collected from each grinding machine as described in ISO 6579:2002 protocol for the detection of Salmonella in food. Of the total 100 samples, 27% were confirmed Salmonella positive, of which 16 were fufu samples while 11 were fufu wash-out samples. Forty-eight percent (48%) of the 50 machines were contaminated with Salmonella. Contamination of wooden machines (85.7%) was higher as compared with the metallic machines (41.9%). The resistance levels of the isolates to the various antibiotics used were as follows: gentamicin (7.1%), nitrofurantoin (18.5%), ciprofloxacin (22.2%), erythromycin (81.5%), ceftazidime (85.2%) and eftriaxone 88.9%). More of the isolates were resistant to three or more antibiotics (81.5% multidrug resistance). From this research, it can be concluded that there is high prevalence of Salmonella isolated from fufu grinding machines in the Tamale metropolis. Measures must be taken by the regulatory authorities to ensure that fufu prepared in grinding machines is safer. Also, awareness creation on antibiotic resistance and strict enforcement of laws on self-prescriptions of drugs would help avert multidrug resistance
Optical Weak Link between Two Spatially Separate Bose-Einstein Condensates
Two spatially separate Bose-Einstein condensates were prepared in an optical
double-well potential. A bidirectional coupling between the two condensates was
established by two pairs of Bragg beams which continuously outcoupled atoms in
opposite directions. The atomic currents induced by the optical coupling depend
on the relative phase of the two condensates and on an additional controllable
coupling phase. This was observed through symmetric and antisymmetric
correlations between the two outcoupled atom fluxes. A Josephson optical
coupling of two condensates in a ring geometry is proposed. The continuous
outcoupling method was used to monitor slow relative motions of two elongated
condensates and characterize the trapping potential.Comment: 4 pages, 5 figure
CT attenuation analysis of carotid intraplaque hemorrhage
Background and Purpose: Intraplaque hemorrhage is considered a leading parameter of carotid plaque vulnerability. Our purpose was to assess the CT characteristics of intraplaque hemorrhage with histopathologic correlation to identify features that allow for confirming or ruling out the intraplaque hemorrhage. MATERIALS AND METHODS: This retrospective study included 91 patients (67 men; median age, 657 years; age range, 41-83 years) who underwent CT angiography and carotid endarterectomy from March 2010 to May 2013. Histopathologic analysis was performed for the tissue characterization and identification of intraplaque hemorrhage. Two observers assessed the plaque's attenuation values by using an ROI (≤1 and ≥2 mm2). Receiver operating characteristic curve, Mann-Whitney, and Wilcoxon analyses were performed. RESULTS: A total of 169 slices were assessed (59 intraplaque hemorrhage, 63 lipid-rich necrotic core, and 47 fibrous); the average values of the intraplaque hemorrhage, lipid-rich necrotic core, and fibrous tissue were 17.475 Hounsfield units (HU) and 18.407 HU, 39.476 HU and 48.048 HU, and 91.66 HU and 93.128 HU, respectively, before and after the administration of contrast medium. The Mann-Whitney test showed a statistically significant difference of HU values both in basal and after the administration of contrast material phase. Receiver operating characteristic analysis showed a statistical association between intraplaque hemorrhage and low HU values, and a threshold of 25 HU demonstrated the presence of intraplaque hemorrhage with a sensitivity and specificity of 93.22% and 92.73%, respectively. The Wilcoxon test showed that the attenuation of the plaque before and after administration of contrast material is different (intraplaque hemorrhage, lipid-rich necrotic core, and fibrous tissue had P values of .006, .0001, and .018, respectively). CONCLUSIONS: The results of this preliminary study suggest that CT can be used to identify the presence of intraplaque hemorrhage according to the attenuation. A threshold of 25 HU in the volume acquired after the administration of contrast medium is associated with an optimal sensitivity and specificity. Special care should be given to the correct identification of the ROI
Quantum reflection of atoms from a solid surface at normal incidence
We observed quantum reflection of ultracold atoms from the attractive
potential of a solid surface. Extremely dilute Bose-Einstein condensates of
^{23}Na, with peak density 10^{11}-10^{12}atoms/cm^3, confined in a weak
gravito-magnetic trap were normally incident on a silicon surface. Reflection
probabilities of up to 20 % were observed for incident velocities of 1-8 mm/s.
The velocity dependence agrees qualitatively with the prediction for quantum
reflection from the attractive Casimir-Polder potential. Atoms confined in a
harmonic trap divided in half by a solid surface exhibited extended lifetime
due to quantum reflection from the surface, implying a reflection probability
above 50 %.Comment: To appear in Phys. Rev. Lett. (December 2004)5 pages, 4 figure
Association between cannabis use and brain imaging phenotypes in UK Biobank: an observational and Mendelian randomization study
Cannabis use during adolescence and young adulthood has been associated with brain structure and functional connectivity. However, despite a rapid increase in cannabis use among older adults in the past decade, the impact on brain structure and function in this population remains understudied. We examined 3,641 self-reported lifetime cannabis users (mean age = 61.00 years, standard deviation (SD) = 7.16) and 12,255 controls (mean age = 64.49 years, SD = 7.58) from the UK Biobank. Brain imaging-derived phenotypes (IDPs) were used as measures of structural and functional connectivity. Associations with cannabis use were assessed using multiple linear regression while controlling for potential confounders. After correcting for false discovery rate (FDR) for multiple testing, in exploratory analyses significant associations were observed with diffusion metrics in the genu of the corpus callosum and with resting-state functional connectivity (rsFC) between the default mode, central executive, and salience networks. Hypothesis-driven analyses did not show any significant association between cannabis use and hippocampal or amygdala volumes. Furthermore, mendelian randomization (MR) analyses did not support a causal relationship between cannabis use and brain structure or function. Our findings indicate that associations between lifetime cannabis use and later life brain structure and function are not likely causal in nature
Hydromechanical analysis of a hydraulic fracturing problem
Hydraulic Fracturing is a well stimulation technique which recently has been widely used for shale gas extraction. Hydraulic fracturing is when a fluid is injected into the wellbore under controlled pressure and flow. The differential pressure generated by the injection of fluid initiates cracks that will propagate into the deep-rock formations, so that it allows the extraction of hydrocarbons trapped into the rock. The technique is used in conventional and unconventional reservoirs of hydrocarbons. In the first case, in conventional reservoirs, the technique is applied in order to increase the production of the well, while in unconventional reservoirs (shale gas) the technique is used to enable the extraction of the gas due to its very low permeability. Furthermore, the process of fracturing the rock at great depths involves the control over the type of fracture created or reactivated, as this will depend on a number of factors. The study of the technique is important to improve the control over the execution of this procedure and also to avoid possible contingencies and accidents. A formulation was implemented in this work capable of representing discontinuities in a continuous mesh using a finite element code. The Extended Finite Element Method (XFEM) was implemented in a hydro-mechanical coupled formulation. Additionally, analyses were performed to identify how the permeability of the rock and the permeability of the fracture influence the hydraulic fracturing. As a result, it was observed that maintaining all of the mechanical properties constant, the hydraulic properties have a great impact on the hydraulic fracturing process. Also, the velocity of propagation of the fracture is affected by the permeability of the rock, and its ratio is inversely proportional
Investigation of partially coherent vector vortex beams with non-isotropic states of spatial correlation
Department of Science and Technology, Ministry of Science and Technology, India ((DST/ICPS/QuST/Theme-I/2019).In this work, the far-field properties of non-isotropic partially coherent vector vortex beams (PCVVBs) are investigated both theoretically and experimentally. The term non-isotropic signifies that the spatial correlations between the parallel and orthogonal electric field components are distinguishable. It is found that self-orientation and shaping of intensity profile, correlation-induced polarization and depolarization are highly dependent on both the non-isotropic correlation parameters and Poincaré-Hopf index (PHI) of the beam. The simultaneous depolarization and polarization effects are due to the difference in the input correlation parameters that alter the state of polarization (SOP) and degree of polarization (DOP) distributions. The experimental results are in good agreement with the theoretical predictions. The distinguishability of correlation parameters at the source plane leads to significant changes on its intensity profile, DOP, and SOP distributions on far-field propagation, which may found potential applications in beam shaping, detecting and imaging atmospheric lidar, optical imaging and directional transportation where the self-rotation characteristic of beam plays an important role.Publisher PDFPeer reviewe
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