This paper provides a clear analysis of how hypothetical concepts not allowed in Special Relativity should be treated and exposes hidden assumptions in space-time diagrams used on YouTube, where some prominent physici...This paper provides a clear analysis of how hypothetical concepts not allowed in Special Relativity should be treated and exposes hidden assumptions in space-time diagrams used on YouTube, where some prominent physicists have taken to publishing on popular topics that may not survive peer review. Such casual graphical treatment conceals the fact that space-time diagrams provide only for the Einstein synchronization convention for all observers, not the many other valid synchronization protocols, and also obscure that relativity’s equality of reference frames is rebutted if concepts outside relativity, such as instant communication, are introduced. These omissions of unconscious assumptions have been used to “prove” the existence of block time and time travel or time paradoxes. We will show the contradictory assumptions amount to assuming time travel, rather than the more mundane need to adjust synchronization conventions. We further show a new result that the use of the space-time diagrams as proposed by these “explainers” leads to discontinuities in which a differential change in communication speed leads to a sudden jump from present to long-past arrival time, strongly suggesting invalidity of the method.展开更多
The feasibility of a Lunar LIGO (Laser Interferometer Gravitational-Wave Observatory) was introduced in 1986 as part of NASA’s planned return to the Moon by the end of the last century. That return to the Moon missio...The feasibility of a Lunar LIGO (Laser Interferometer Gravitational-Wave Observatory) was introduced in 1986 as part of NASA’s planned return to the Moon by the end of the last century. That return to the Moon mission was cancelled, but is once again planned as Artemis in 2024. In this paper, the feasibility of such a Lunar LIGO as part of NASA’s return there will be discussed for that program. Details of the physics of the original Lunar LIGO proposal as a potential portion of future lunar base astronomy and astrophysics designs are presented. Results from NASA’s original planned return to the Moon to establish a gravitational wave observatory there are presented and discussed.展开更多
Background: The effect of the K?hler group dynamics paradigm(i.e., working together with a more capable partner where one's performance is indispensable to the team outcome) has been shown to increase motivation t...Background: The effect of the K?hler group dynamics paradigm(i.e., working together with a more capable partner where one's performance is indispensable to the team outcome) has been shown to increase motivation to exercise longer at a strength task in partnered exercise video games (exergames) using a software-generated partner(SGP). However, the effect on exercise intensity with an SGP has not been investigated. The purpose of this study was to examine the motivation to maintain or increase exercise intensity among healthy, physically active middle-aged adults using an SGP in an aerobic exergame.Methods: Participants(n = 85, mean age = 44.9 years) exercised with an SGP in a 6-day cycle ergometer protocol, randomly assigned to either(a)no partner control,(b) superior SGP who was not a teammate, or(c) superior SGP as a teammate(team score was dependent on the inferior member). The protocol alternated between 30-min continuous and 4-min interval lhigh-intensity session days, during which participants could change cycle power output(watts) from target intensity to alter distance and speed.Results: Mean change in watts from a targeted intensity(75% and 90% maximum heart rate) was the primary dependent variable reflecting motivational effort. Increases in performance over baseline were demonstrated without significant differences between conditions. Self-efficacy and enjoyment were significantly related to effort in the more intense interval sessions.Conclusion: Under these conditions, no K?hler effect was observed. Exercise performance during the higher-intensity interval format is more closely related to enloyment and self-efficacy beliefs compared to the continuous sessions.展开更多
Short-leg walking boots are a common intervention for acute and chronic lower extremity injury.Few studies have examined the neuromuscular adaptations associated with short-leg walking boots and no previous study has ...Short-leg walking boots are a common intervention for acute and chronic lower extremity injury.Few studies have examined the neuromuscular adaptations associated with short-leg walking boots and no previous study has investigated timing characteristics of muscle activation during gait.The purpose of the current study was to examine the timing and amplitudes of muscle activation of the extrinsic ankle musculature during walking in two types of short-leg walking boots.Methods:Eleven healthy young adults performed five level walking trials at a self-selected pace in each of three conditions:normal walking,Gait Walker and Equalizer short-leg walking boots.Ground reaction forces were collected from a force platform while surface electromyography (EMG)was collected from the tibialis anterior,peroneus longus and medial gastrocnemius.EMG signals were rectified and smoothed using the root mean squared with a 20-ms smoothing window and were normalized to the largest mean of the normal walking trials.A repeated measures analysis of variance was used to assess the effect of short-leg walking boots on the onset,duration and amplitude of muscle activation.Results:Short-leg walking boots were generally associated with earlier onsets of muscle activation and longer durations of muscle activation.However,there was no reduction in EMG amplitude.Conclusion:The findings of this study show that the induced alterations in muscle activation patterns may limit the short-leg walking boots.Copyright(C)2012,Shanghai University of Sport.Production and hosting by Elsevier B.V.All rights reserved.展开更多
A 41-year-old woman developed skin lesions on her upper back and arm. Initially, a definitive diagnosis could not be made. Subsequently, PCR detected VZV DNA in skin lesions and saliva. Immediate antiviral treatment l...A 41-year-old woman developed skin lesions on her upper back and arm. Initially, a definitive diagnosis could not be made. Subsequently, PCR detected VZV DNA in skin lesions and saliva. Immediate antiviral treatment led to a quick recovery without complicating prolonged fatigue and weakness typically seen in adults with varicella.展开更多
The twins or clock paradox has been a subject of lively discussion and occasional disagreement among both relativists and the public for over 100 years, and continues to attract physicists who write papers giving new ...The twins or clock paradox has been a subject of lively discussion and occasional disagreement among both relativists and the public for over 100 years, and continues to attract physicists who write papers giving new analyses or defending old ones, even though many physicists now consider the matter only of educational interest. This paper investigates the number of papers, which is increasing, and trends in explanations, some of which are now targeted at professional physicists and other of which are targeted at optical or radar visualization rather than problem solving. Observations of students indicate that the latest techniques help but only somewhat. An analysis is made of 21 previous treatments appearing in the education related American Journal of Physics, Einstein’s discussions and several other pedagogical papers. A new memory aid for simultaneity transformation is given that puts it on a par with “time dilation” and “length contraction” for quick and easy problem visualization. The point of view of a trailing twin is introduced to show how simultaneity changes account for missing time in the turnaround. Length contraction is treated on equal footing with time dilation, and Swann’s insight into clocks is extended to lengths. Treatments using the conventionality of simultaneity are seen as equivalent to choice of co-moving frames. Responses to difficult questions are suggested which avoid being dismissive, and engage students’ critical thinking.展开更多
Using security incident history we identify threats to and using the IoT and other ubiquitous devices emerging since 2012, gaining widespread recognition in 2016, and only lightly addressed in either IoT security lite...Using security incident history we identify threats to and using the IoT and other ubiquitous devices emerging since 2012, gaining widespread recognition in 2016, and only lightly addressed in either IoT security literature or the press. We show the IoT has likely already been used in cyber war between major powers. The new threats, most notably “hijack,” are larger than previous threats combined, but only mildly affect suppliers, and only a few clients. Using a successful behavioral-economic model we show that traditional mitigation places responsibility on un-affected parties and likely will not work. For suppliers, there are profit-conflicted motives, as the new threat rides on a profit vehicle. The new threat circumvents conventional security architecture at a behavioral level. We analyze each actor-target pair and evaluate technical strategies. More effective technical strategies are suggested where old ones are overmatched by the budgets, technical prowess or regulatory power of hostile actors, or the technical nature of the threats. Consolidated action may be needed, but regulation is difficult because of conflicts of interest within the national security community.展开更多
This paper will discuss the current viewpoint of the vacuum state and explore the idea of a “natural” vacuum as opposed to immutable, non-degradable vacuum. This concept will be explored for all primary quantum numb...This paper will discuss the current viewpoint of the vacuum state and explore the idea of a “natural” vacuum as opposed to immutable, non-degradable vacuum. This concept will be explored for all primary quantum numbers to show consistency with observation at the level of Bohr theory. A comparison with the Casimir force per unit area will be made, and an explicit function for the spatial variation of the vacuum density around the atomic nucleus will be derived. This explicit function will be numerically modeled using the industry multi-physics tool, COMSOL, and the eigenfrequencies for the n = 1 to n = 7 states will be found and compared to expectation.展开更多
A new approach to solving two of the cosmological constant problems (CCPs) is proposed by introducing the Abbott-Deser (AD) method for defining Killing charges in asymptotic de Sitter space as the only consistent mean...A new approach to solving two of the cosmological constant problems (CCPs) is proposed by introducing the Abbott-Deser (AD) method for defining Killing charges in asymptotic de Sitter space as the only consistent means for defining the ground-state vacuum for the CCP. That granted, Einstein gravity will also need to be modified at short-distance nuclear scales, using instead a nonminimally coupled scalar-tensor theory of gravitation that provides for the existence of QCD’s two-phase vacuum having two different zero-point energy states as a function of temperature. Einstein gravity alone cannot accomplish this. The scalar field will be taken from bag theory in hadron physics, and the origin of the bag constant B is accounted for by gravity’s CC as B—noting that the Higgs mechanism does not account for either the curved-space origin of λ or the mass of composite hadrons. A small Hubble-scale graviton mass mg^10-33eV naturally appears external to the hadron bag, induced by λ≠0. This mass is unobservable and gravitationally gauge-dependent. It is shown to be related to the cosmological event horizon in asymptotic de Sitter space.展开更多
In spite of tremendous progress in experimental high-energy physics such as the apparent discovery of the Higgs boson at CERN, there exist a number of inconsistencies in theoretical physics which continue to go either...In spite of tremendous progress in experimental high-energy physics such as the apparent discovery of the Higgs boson at CERN, there exist a number of inconsistencies in theoretical physics which continue to go either unnoticed or unstated. These include the Higgs mechanism itself as well as recent discussions of problems with inflationary cosmology. The subject will be addressed in the context of this author’s recent paper [1] 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003400310031003900330032003700350034000000 on the requirement for compatible asymptotic states in the study of the cosmological constant problem (CCP). Inconsistency in the Higgs mechanism is eliminated by using scalar-tensor gravity where the scalar field is a gravitational field with zero spin that represents the spontaneous symmetry breaking potential.展开更多
Soft structural textiles,or softgoods,are used within the space industry for inflatable habitats,parachutes and decelerator systems.Evaluating the safety and structural integrity of these systems occurs through struct...Soft structural textiles,or softgoods,are used within the space industry for inflatable habitats,parachutes and decelerator systems.Evaluating the safety and structural integrity of these systems occurs through structural health monitoring systems(SHM),which integrate non-invasive/non-destructive testing methods to detect,diagnose,and locate damage.Strain/load monitoring of these systems is limited while utilizing traditional strain gauges as these gauges are typically stiff,operate at low temperatures,and fail when subjected to high strain that is a result of high loading classifying them as unsuitable for SHM of soft structural textiles.For this work,a capacitance based strain gauge(CSG)was fabricated via aerosol jet printing(AJP)using silver nanoparticle ink on a flexible polymer substrate.Printed strain gauges were then compared to a commercially available high elongation resistance-based strain gauge(HE-RSG)for their ability to monitor strained Kevlar straps having a 26.7 kN(6 klbf)load.Dynamic,static and cyclic loads were used to characterize both types of strain monitoring devices.Printed CSGs demonstrated superior performance for high elongation strain measurements when compared to commonly used HE-RSGs,and were observed to operate with a gauge factor of 5.2 when the electrode arrangement was perpendicular to the direction of strain.展开更多
Many potential applications of carbon nanotubes are expected to benet from the availability of single-walled carbon nanotube materials enriched in metallic species,and specifically armchair nanotubes.The present work...Many potential applications of carbon nanotubes are expected to benet from the availability of single-walled carbon nanotube materials enriched in metallic species,and specifically armchair nanotubes.The present work focuses on the modification of the pulsed laser vaporization(PLV)technique to selectively produce certain carbon nanotube structures.Nanotube nuclei were“warmed-up”with an additional laser pulse,timed to coincide approximately with the nucleation event.The effect of the second laser on the carbon vapor temperature was studied by emission spectroscopy.Nanotube type populations with and without warm-up were compared by means of absorption,photoluminescence,and Raman spectroscopy.It was found that the warm-up of nanotube nuclei with a laser pulse has a noticeable,albeit small,effect on the nanotube population.The intensity of spectral features associated with(9,7)nanotube and its large chiral angle neighbors increased,while small chiral angle nanotubes decreased,with exception of the(15,0)tube.This experiment demonstrates that nanotube population during PLV synthesis can be manipulated in a controlled fashion.展开更多
文摘This paper provides a clear analysis of how hypothetical concepts not allowed in Special Relativity should be treated and exposes hidden assumptions in space-time diagrams used on YouTube, where some prominent physicists have taken to publishing on popular topics that may not survive peer review. Such casual graphical treatment conceals the fact that space-time diagrams provide only for the Einstein synchronization convention for all observers, not the many other valid synchronization protocols, and also obscure that relativity’s equality of reference frames is rebutted if concepts outside relativity, such as instant communication, are introduced. These omissions of unconscious assumptions have been used to “prove” the existence of block time and time travel or time paradoxes. We will show the contradictory assumptions amount to assuming time travel, rather than the more mundane need to adjust synchronization conventions. We further show a new result that the use of the space-time diagrams as proposed by these “explainers” leads to discontinuities in which a differential change in communication speed leads to a sudden jump from present to long-past arrival time, strongly suggesting invalidity of the method.
文摘The feasibility of a Lunar LIGO (Laser Interferometer Gravitational-Wave Observatory) was introduced in 1986 as part of NASA’s planned return to the Moon by the end of the last century. That return to the Moon mission was cancelled, but is once again planned as Artemis in 2024. In this paper, the feasibility of such a Lunar LIGO as part of NASA’s return there will be discussed for that program. Details of the physics of the original Lunar LIGO proposal as a potential portion of future lunar base astronomy and astrophysics designs are presented. Results from NASA’s original planned return to the Moon to establish a gravitational wave observatory there are presented and discussed.
基金supported by research grant #MA03401 (Feltz,PI),NASA/National Space Biomedical Research
文摘Background: The effect of the K?hler group dynamics paradigm(i.e., working together with a more capable partner where one's performance is indispensable to the team outcome) has been shown to increase motivation to exercise longer at a strength task in partnered exercise video games (exergames) using a software-generated partner(SGP). However, the effect on exercise intensity with an SGP has not been investigated. The purpose of this study was to examine the motivation to maintain or increase exercise intensity among healthy, physically active middle-aged adults using an SGP in an aerobic exergame.Methods: Participants(n = 85, mean age = 44.9 years) exercised with an SGP in a 6-day cycle ergometer protocol, randomly assigned to either(a)no partner control,(b) superior SGP who was not a teammate, or(c) superior SGP as a teammate(team score was dependent on the inferior member). The protocol alternated between 30-min continuous and 4-min interval lhigh-intensity session days, during which participants could change cycle power output(watts) from target intensity to alter distance and speed.Results: Mean change in watts from a targeted intensity(75% and 90% maximum heart rate) was the primary dependent variable reflecting motivational effort. Increases in performance over baseline were demonstrated without significant differences between conditions. Self-efficacy and enjoyment were significantly related to effort in the more intense interval sessions.Conclusion: Under these conditions, no K?hler effect was observed. Exercise performance during the higher-intensity interval format is more closely related to enloyment and self-efficacy beliefs compared to the continuous sessions.
基金funded in part by a grant from DeRoyal Industries,Inc.,Powell,TN,USA
文摘Short-leg walking boots are a common intervention for acute and chronic lower extremity injury.Few studies have examined the neuromuscular adaptations associated with short-leg walking boots and no previous study has investigated timing characteristics of muscle activation during gait.The purpose of the current study was to examine the timing and amplitudes of muscle activation of the extrinsic ankle musculature during walking in two types of short-leg walking boots.Methods:Eleven healthy young adults performed five level walking trials at a self-selected pace in each of three conditions:normal walking,Gait Walker and Equalizer short-leg walking boots.Ground reaction forces were collected from a force platform while surface electromyography (EMG)was collected from the tibialis anterior,peroneus longus and medial gastrocnemius.EMG signals were rectified and smoothed using the root mean squared with a 20-ms smoothing window and were normalized to the largest mean of the normal walking trials.A repeated measures analysis of variance was used to assess the effect of short-leg walking boots on the onset,duration and amplitude of muscle activation.Results:Short-leg walking boots were generally associated with earlier onsets of muscle activation and longer durations of muscle activation.However,there was no reduction in EMG amplitude.Conclusion:The findings of this study show that the induced alterations in muscle activation patterns may limit the short-leg walking boots.Copyright(C)2012,Shanghai University of Sport.Production and hosting by Elsevier B.V.All rights reserved.
文摘A 41-year-old woman developed skin lesions on her upper back and arm. Initially, a definitive diagnosis could not be made. Subsequently, PCR detected VZV DNA in skin lesions and saliva. Immediate antiviral treatment led to a quick recovery without complicating prolonged fatigue and weakness typically seen in adults with varicella.
文摘The twins or clock paradox has been a subject of lively discussion and occasional disagreement among both relativists and the public for over 100 years, and continues to attract physicists who write papers giving new analyses or defending old ones, even though many physicists now consider the matter only of educational interest. This paper investigates the number of papers, which is increasing, and trends in explanations, some of which are now targeted at professional physicists and other of which are targeted at optical or radar visualization rather than problem solving. Observations of students indicate that the latest techniques help but only somewhat. An analysis is made of 21 previous treatments appearing in the education related American Journal of Physics, Einstein’s discussions and several other pedagogical papers. A new memory aid for simultaneity transformation is given that puts it on a par with “time dilation” and “length contraction” for quick and easy problem visualization. The point of view of a trailing twin is introduced to show how simultaneity changes account for missing time in the turnaround. Length contraction is treated on equal footing with time dilation, and Swann’s insight into clocks is extended to lengths. Treatments using the conventionality of simultaneity are seen as equivalent to choice of co-moving frames. Responses to difficult questions are suggested which avoid being dismissive, and engage students’ critical thinking.
文摘Using security incident history we identify threats to and using the IoT and other ubiquitous devices emerging since 2012, gaining widespread recognition in 2016, and only lightly addressed in either IoT security literature or the press. We show the IoT has likely already been used in cyber war between major powers. The new threats, most notably “hijack,” are larger than previous threats combined, but only mildly affect suppliers, and only a few clients. Using a successful behavioral-economic model we show that traditional mitigation places responsibility on un-affected parties and likely will not work. For suppliers, there are profit-conflicted motives, as the new threat rides on a profit vehicle. The new threat circumvents conventional security architecture at a behavioral level. We analyze each actor-target pair and evaluate technical strategies. More effective technical strategies are suggested where old ones are overmatched by the budgets, technical prowess or regulatory power of hostile actors, or the technical nature of the threats. Consolidated action may be needed, but regulation is difficult because of conflicts of interest within the national security community.
文摘This paper will discuss the current viewpoint of the vacuum state and explore the idea of a “natural” vacuum as opposed to immutable, non-degradable vacuum. This concept will be explored for all primary quantum numbers to show consistency with observation at the level of Bohr theory. A comparison with the Casimir force per unit area will be made, and an explicit function for the spatial variation of the vacuum density around the atomic nucleus will be derived. This explicit function will be numerically modeled using the industry multi-physics tool, COMSOL, and the eigenfrequencies for the n = 1 to n = 7 states will be found and compared to expectation.
文摘A new approach to solving two of the cosmological constant problems (CCPs) is proposed by introducing the Abbott-Deser (AD) method for defining Killing charges in asymptotic de Sitter space as the only consistent means for defining the ground-state vacuum for the CCP. That granted, Einstein gravity will also need to be modified at short-distance nuclear scales, using instead a nonminimally coupled scalar-tensor theory of gravitation that provides for the existence of QCD’s two-phase vacuum having two different zero-point energy states as a function of temperature. Einstein gravity alone cannot accomplish this. The scalar field will be taken from bag theory in hadron physics, and the origin of the bag constant B is accounted for by gravity’s CC as B—noting that the Higgs mechanism does not account for either the curved-space origin of λ or the mass of composite hadrons. A small Hubble-scale graviton mass mg^10-33eV naturally appears external to the hadron bag, induced by λ≠0. This mass is unobservable and gravitationally gauge-dependent. It is shown to be related to the cosmological event horizon in asymptotic de Sitter space.
文摘In spite of tremendous progress in experimental high-energy physics such as the apparent discovery of the Higgs boson at CERN, there exist a number of inconsistencies in theoretical physics which continue to go either unnoticed or unstated. These include the Higgs mechanism itself as well as recent discussions of problems with inflationary cosmology. The subject will be addressed in the context of this author’s recent paper [1] 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003400310031003900330032003700350034000000 on the requirement for compatible asymptotic states in the study of the cosmological constant problem (CCP). Inconsistency in the Higgs mechanism is eliminated by using scalar-tensor gravity where the scalar field is a gravitational field with zero spin that represents the spontaneous symmetry breaking potential.
基金This material is based upon work supported under an Integrated University Program Graduate Fellowship,and was supported in part by Department of Energy In-Pile Instrumentation program under DOE Idaho Operations Office Contract DE-AC07-05ID14517 and by the National Aeronautics Space Administration under award#80NSSC18M0088The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S.Government or any agency thereof.D.E.also acknowledges career development support by Institutional Development Awards(IDeA)from the National Institute of General Medical Sciences of the National Institutes of Health under Grants#P20GM103408 and P20GM109095.
文摘Soft structural textiles,or softgoods,are used within the space industry for inflatable habitats,parachutes and decelerator systems.Evaluating the safety and structural integrity of these systems occurs through structural health monitoring systems(SHM),which integrate non-invasive/non-destructive testing methods to detect,diagnose,and locate damage.Strain/load monitoring of these systems is limited while utilizing traditional strain gauges as these gauges are typically stiff,operate at low temperatures,and fail when subjected to high strain that is a result of high loading classifying them as unsuitable for SHM of soft structural textiles.For this work,a capacitance based strain gauge(CSG)was fabricated via aerosol jet printing(AJP)using silver nanoparticle ink on a flexible polymer substrate.Printed strain gauges were then compared to a commercially available high elongation resistance-based strain gauge(HE-RSG)for their ability to monitor strained Kevlar straps having a 26.7 kN(6 klbf)load.Dynamic,static and cyclic loads were used to characterize both types of strain monitoring devices.Printed CSGs demonstrated superior performance for high elongation strain measurements when compared to commonly used HE-RSGs,and were observed to operate with a gauge factor of 5.2 when the electrode arrangement was perpendicular to the direction of strain.
基金The authors would like to acknowledge financial support from NASA under contract#NNJ05HI05C and from State of Texas,Space Act Agreement#SAA-AT-07-021(RAN 0798)(UTA07-099).The authors thank Dr.R.Bruce Weisman and Saunab Ghosh of Rice University for help with photoluminescence measurements.
文摘Many potential applications of carbon nanotubes are expected to benet from the availability of single-walled carbon nanotube materials enriched in metallic species,and specifically armchair nanotubes.The present work focuses on the modification of the pulsed laser vaporization(PLV)technique to selectively produce certain carbon nanotube structures.Nanotube nuclei were“warmed-up”with an additional laser pulse,timed to coincide approximately with the nucleation event.The effect of the second laser on the carbon vapor temperature was studied by emission spectroscopy.Nanotube type populations with and without warm-up were compared by means of absorption,photoluminescence,and Raman spectroscopy.It was found that the warm-up of nanotube nuclei with a laser pulse has a noticeable,albeit small,effect on the nanotube population.The intensity of spectral features associated with(9,7)nanotube and its large chiral angle neighbors increased,while small chiral angle nanotubes decreased,with exception of the(15,0)tube.This experiment demonstrates that nanotube population during PLV synthesis can be manipulated in a controlled fashion.
