ISSN / EISSN : 2150-4091 / 2150-4105
Current Publisher: Scientific Research Publishing, Inc. (10.4236)
Total articles ≅ 1,134
Latest articles in this journal
Natural Science, Volume 13, pp 43-75; doi:10.4236/ns.2021.133006
In this review paper, the remarkable impacts of the first Internet Institute, the Gordon Life Science Institute, as well as its profound and far-reaching influence have been systematically and comprehensively presented.
Natural Science, Volume 13, pp 9-17; doi:10.4236/ns.2021.132002
Objective of the study: This study aimed at characterizing output features of the higher-order motor control centers (hoMCCs), including secondary (premotor cortex [Pre] and supplementary motor area [SMA]) and association (prefrontal cortex [PFC]) motor regions to the primary motor cortex (M1) during graded force tasks. It is well known that one of the major roles of the primary motor cortex (M1) is controlling motor output such as muscle force. However, it is unclear how the hoMCCs interact with M1 in regulating voluntary muscle contractions. Methods: fMRI data was acquired during graded force tasks and fMRI-based effective connectivity (EC) and muscle force analyses were performed to study the relationship between hoMCCs-M1 effective connectivity and voluntarily exerted handgrip force. Results: The results show that there is a consistent information flow from the hoMCCs to M1 under all force conditions, suggesting a hierarchical control mechanism in the brain in regulating voluntary muscle force. Only the premotor cortex exhibited a significant role in mediating the level of force production through its EC with M1 but that role diminished when the exerted force was high, suggesting perhaps a ceiling and/or fatigue effect on the EC. A flip in the direction of EC from the primary sensory cortex (S1) to the hoMCCs (PFC, SMA, and Pre) at lower force levels while at higher forces EC was observed from the hoMCCs to S1. Conclusion: The hoMCCs regulate M1 output to produce desired voluntary muscle force. Only the Pre-to-M1 connectivity strength directly correlates with the force level especially from low to moderate levels. The hoMCCs are involved in modulating higher force production likely by strengthening M1 output and downgrading inhibition from S1 to M1.
Natural Science, Volume 13, pp 21-25; doi:10.4236/ns.2021.132004
The purpose of this note is to stimulate interest in measuring and characterizing the emitted ultraviolet frequencies in antimicrobial copper materials. Antimicrobial sanitizing materials are urgently needed to limit the spread of COVID-19 virus. In the current pandemic, ultraviolet radiation is often used for sterilization. It is shown that 3 d-orbital capture in copper can result in radiation generated by copper materials. Since ultraviolet radiation is known to be effective in antimicrobial sterilization, it is logical to assume that the radiation formed by copper occurs in the ultraviolet region. Electron transitions in 3 d-orbital capture are expected to occur in this region. A description of the 3 d-orbital capture process, and the origin of the associated frequency, is given. It is shown that for Group 1B elements the strength of electron affinity in the d-orbital capture process increases with increasing Periodic Table period number, n. This is the opposite of other electron affinity properties for atoms that decrease wth an increase in n. A brief discussion of the relationship of d-orbital capture to the chemical inertness of gold is given. The same type of d-orbital capture process that occurs in antimicrobial copper occurs in high temperature superconducting cuprates.
Natural Science, Volume 13, pp 26-41; doi:10.4236/ns.2021.132005
Drought stress in plants is accompanied by several metabolic changes. One of them is the appearance of N-malonyltryptophan (MT) during leaf wilting of many species, but there is a significant number of plant species in which the appearance of MT did not occur. Plants of some species were able to synthesize also N-acetyltryptophan (AT). Excised tomato leaves incubated with D-amino acids (including D-Trp) transform them into malonyl- and acetyl-derivatives even without water deficit. However, MT which appeared during water deficit has been shown to contain L-Trp. Amino acid—1-amino-cyclopropane-1-carboxylic acid (ACC) is also malonylated during water deficit, but other L-amino acids were not malonylated. N-malonyl transferases specific for Trp and ACC have been found in several plants. The existence of N-malonyltransferase specific to L-Trp and appeared during water deficit in plants forming MT is supposed, but clear experimental proof has not been obtained yet. Plants can transform MT applied exogenously into Trp and further to indole-3-acetic acid (IAA). But no evidence has been appeared up to now that endogenous MT may be a source of IAA. It is unknown till now why it is necessary for plants of many species to malonylate only Trp during water deficit. How MT metabolized in animals and if it affects them is also unknown. The necessity to use molecular-genetic approaches for the elucidation of the physiological significance of MT formation during water deficit is underlined.
Natural Science, Volume 13, pp 91-102; doi:10.4236/ns.2021.133009
In this work, Laser Induced Breakdown Spectroscopy (LIBS) was used to determine the constituent of Gum Arabic (Acacia nilotica) collected from five different locations in Sudan. Gum samples were irradiated with 80 mJ pulse energy of Nd-YAG laser (1064 nm) and Atomic spectra Database was used for the spectral analysis of the plasma emitted from these samples. It was found that the samples contain the elements C, O, H, S, N, P, Na, Mg, Ca, Fe, Cr, Mn, Co with different amounts. Some elements like (Ti, Br, Ar, Th, Kr, Sc and Pr) are recorded here for the first time.
Natural Science, Volume 13, pp 88-90; doi:10.4236/ns.2021.133008
Natural Science, Volume 13, pp 18-20; doi:10.4236/ns.2021.132003
Fluid particles in translating surface gravity waves have an orbital motion which decreases in size with increasing mean depth. These wave characteristics came from observations and were not forecast theoretically. The classical potential flow model is incapable of explaining the particle movement due to the irrotational assumption and to a flaw in carrying out the method. When a wave passes by an observer from left to right, the particles move clockwise under a crest and a trough. This correct conclusion is consistent with what the incorrect standard theory implies but should not be considered to have been derived from it.
Natural Science, Volume 13, pp 1-7; doi:10.4236/ns.2021.131001
This paper discusses the “Hubble constant measurement—mystery”. Independent measurements of this cosmic parameter, referred to as H0 in abbreviated form, have all led to different values, with the highest value ≈ 74 km·s-1·Mpc-1 and the lowest ≈ 67 km·s-1·Mpc-1, where km denotes kilometer, s second and Mpc-1 megaparsec. These measurements have mainly been obtained with space telescopes. Apparently, up to now there was no way to explain the differences. However, previously published studies seem to regard the problem of the different measurement results for H0 [1, 2]. I have shown that due to a symmetrical expansion of the Minkowski space (SMS), each respective frame of reference for an observer, who rests in the zero point of the frame, is converted into a state of apparent rest relative to the cosmic microwave background (CMB) radiation. This SMS-relativistic effect also seems to be responsible for the different measurement results of the Hubble constant, especially through space telescopes.
Natural Science, Volume 13, pp 133-135; doi:10.4236/ns.2021.134012
A first attempt has been made to confirm experimentally a theoretical concept, recently published, involving a rigid cone rotating about its long axis under still water: it should tend to translate along that axis blunt end leading and apex trailing. Two identical hollow cones, neutrally buoyant, with equal weights attached to the apexes, were released simultaneously at the surface of a swimming pool. One cone had a thin light weight spiral vane vertically attached to the cone’s outside surface in order to cause it to rotate as it sank. Several trial runs were made in the shallow and deep ends of the pool, and in every case, the non-rotating cone without a vane hit the bottom of the pool first. These comparisons qualitatively and indirectly validate the prediction.
Natural Science, Volume 13, pp 117-132; doi:10.4236/ns.2021.134011
At some future time, each person alive today will be either an ancestor of everyone or an ancestor of no one. If the global population were unstructured by geography, race, religion and other factors, the time to future common ancestry for present-day humans would be between 33 and 66 generations, or about 1000 - 2000 years. In a structured population, migration and intermarriage are the necessary conditions for global common ancestry. Simulation of random and hierarchical migration models, shows that time to future global ancestry is generally less than triple, and often less than twice, that required for an unstructured population. The models suggest that someone alive today will become a common ancestor of the entire world population by about 5000 CE, or sooner; and that all current humans who are destined to become global common ancestors will be so by about 8000 CE, or sooner. At which time, everybody then alive will have the exact same genealogical ancestors from the present day.