scholarly journals Gravitational Radiation, Vorticity And Super–Energy: A Conspicuous Threesome

Universe ◽  
2019 ◽  
Vol 5 (7) ◽  
pp. 164 ◽  
Author(s):  
Luis Herrera
Keyword(s):  
Gravitational Radiation ◽  
Fluid Distribution ◽  
Ring Lasers ◽  
Vorticity Vector ◽  
Atom Lasers ◽  
Open Question ◽  
High Degree ◽  
Laser Interferometers ◽  
The Waves ◽  
Theoretical Issues

We elaborate on the link relating gravitational radiation, vorticity and a flux of super–energy on the plane orthogonal to the vorticity vector. We examine the vorticity appearing in the congruence of observers at the outside of the source, as well as the vorticity of the fluid distribution, the source of the gravitational radiation is made of. The information provided by the study of the physical aspects of the source poses new questions which could, in principle, be solved by the observational evidence. Besides the study of the theoretical issues associated to such relationship, we also stress the new observational possibilities to detect gravitational radiation, appearing as consequence of the above mentioned link. The high degree of development achieved in the gyroscope technology, as well as recent proposals to detect rotations by means of ring lasers, atom interferometers, atom lasers and anomalous spin–precession experiments, lead us to believe that an alternative to the laser interferometers used so far to detect gravitational waves, may be implemented based on the detection of the vorticity associated with gravitational radiation. Additionally, this kind of detectors might be able to elucidate the open question about the physical properties of the tail of the waves appearing as the consequence of the violation of the Huygens’s principle in general relativity.

scholarly journals A network of heterodyne laser interferometers for monitoring and control of large ring-lasers

2016 ◽  
Author(s):  
Alberto Donazzan ◽  
Giampiero Naletto ◽  
Maria G. Pelizzo ◽  
Davide Cuccato ◽  
Alessandro Beghi ◽  
...  
Keyword(s):  
Monitoring And Control ◽  
Large Ring ◽  
Ring Lasers ◽  
And Control ◽  
Laser Interferometers

The Negative Effects of Using Smart Devices on the Physical and Psychological Health of Palestinian Children aged (13-16) years from their Perspective

2020 ◽  
Vol 8 (3) ◽  
pp. 01-19
Author(s):  
Nuha Iter
Keyword(s):  
Psychological Health ◽  
Smart Devices ◽  
Smart Device ◽  
Negative Effects ◽  
Physical And Psychological Health ◽  
Palestinian Children ◽  
Open Question ◽  
High Degree ◽  
The Relationship ◽  
Descriptive Method

The study aimed to explore the negative effects of using smart devices on the physical and psychological health of children aged (13-16) years from their perspective. The study was applied to a random sample of children aged (13-16), consisting of (102) male and female students. The descriptive method was used to answer the study questions, and a questionnaire was developed to collect data, which contains (3) sections, first section asked about the most used and preferred devices by children aged (13-16) years, and the number of hours the child used the smart device, the second one asked about the negative effects of using the smart devices on the physical and psychological health of children aged (13-16) years from their perspective, and the third section is an open question to know other negative effects of using the smart devices on the physical and psychological health of children aged (13-16) years. The study achieved a set of results, such as the smartphones are the most used and preferred devices by children aged (13-16) years, where (57%) of the study sample preferred to use, and there is  (86.3%) of children aged (13-16) use these devices at average from 4 up to 6 hours daily.  The responders highly agreed upon the negative effects of the use of smart devices on the physical health with average (4.2); which is a high degree, also the responders highly agreed upon the negative effects of  the use of smart devices on the physiological health with average  is  (3.73) which is also high,  added there are other effects caused by the use of smart devices for long hours on  children aged (13-16); the low rate of family discussions, and causes the low writing skills for child.   Depending on the results of the study, the researcher recommends that:  researchers should conduct a correlative study to know the relationship between the effects and the number of hours of daily use of devices; families should rationalize the use of smart devices.

SOGRO — Terrestrial full-tensor detector for mid-frequency gravitational waves

2019 ◽  
Vol 29 (04) ◽  
pp. 1940001 ◽  
Author(s):  
Ho Jung Paik ◽  
M. Vol Moody ◽  
Ronald S. Norton
Keyword(s):  
Laser Interferometer ◽  
Newtonian Gravity ◽  
Cryogenic Temperatures ◽  
Wave Polarization ◽  
Future Space ◽  
Single Detector ◽  
Frequency Window ◽  
High Degree ◽  
Laser Interferometers ◽  
Very High

Laser interferometer gravitational-wave (GW) detectors are observing signals from merging black hole and neutron star binaries with a frequency window from 10[Formula: see text]Hz to several kHz. Future space-based laser interferometers will open a new window of 0.1[Formula: see text]mHz to 0.1[Formula: see text]Hz. In this paper, we discuss the possibility of constructing a terrestrial GW detector named Superconducting Omni-directional Gravitational Radiation Observatory (SOGRO), which can fill the missing frequency window, 0.1 to 10[Formula: see text]Hz, with astronomically interesting sensitivity. SOGRO measures all five tensor components of the spacetime metric, which results in uniform sensitivity for all-sky directions and enables identification of the source direction and wave polarization with a single detector. Seismic and Newtonian gravity noise pose the greatest challenges for constructing ground-based detectors below 10[Formula: see text]Hz. SOGRO utilizes enhanced mechanical and electrical stabilities of materials at cryogenic temperatures to reject common-mode seismic noise to a very high degree. Further, its full-tensor characteristic gives an advantage in the rejection of the Newtonian noise over conventional detectors.

Evaluating future beach reduction in a changing climate: Methodologies and uncertainties.

2020 ◽  
Author(s):  
Miguel Agulles ◽  
Gabriel Jordà
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Climate Change Impacts ◽  
Cost Effective ◽  
Swash Zone ◽  
Wave Runup ◽  
First Results ◽  
High Degree ◽  
The Impact ◽  
The Waves

<p>In recent years there have been endless coastal actions that have substantially modified the equilibrium conditions of much of the coastline. This fact, along with an unprecedented coastal population growth and the projected sea level rise, make beaches a particularly vulnerable region to climate change impacts. In particular, there is a clear need to quantify the reduction of the beach area due to the combination effects of the sea level rise and changes in the waves in the swash zone, under different future climate scenarios.</p><p>In this work different methodologies are developed to estimate the retreat of the coastline and to quantify the associated uncertainties. The methodologies have been applied to three beaches of the Balearic Islands, which have been continuously monitored during the last decade. The different methodologies imply the use of models to propagate the waves from deep waters to shallow depths and to compute wave runup. The results are compared to simpler approaches based on empirical formulations that provide a cost-effective solution to cover large domains. All the different approaches are validated with coastal wave recorders (AWACs) and data from cameras from which wave runup is estimated. Furthermore, a sensitivity analysis has been performed to assess the impact of uncertainties in the beach bathymetry.</p><p>The first results show that under the RCP8.5 scenario, the expected coastline retreat under mean conditions would be of ~22 ± 5 meters at mid-century. Considering extreme waves conditions, the retreat would reach ~40 ± 5 meters.</p><p>It is worth mentioning that the three studied beaches have a very different exposure, granulometry and maritime climate, and in spite of that, the estimated uncertainty level is relatively low (~10-25%) in all of them. Therefore, the proposed methodologies along with their uncertainty analysis, might be extrapolated to any sandy beach with a reasonable high degree of accuracy. </p>

scholarly journals Distinct gene expression dynamics in developing and regenerating limbs

2021 ◽  
Author(s):  
Chiara Sinigaglia ◽  
Alba Almazan ◽  
Marie Semon ◽  
Benjamin Gillet ◽  
Sandrine Hughes ◽  
...  
Keyword(s):  
Gene Expression ◽  
Temporal Patterns ◽  
Molting Cycle ◽  
Transcriptional Dynamics ◽  
Gene Sets ◽  
Leg Development ◽  
Gene Expression Dynamics ◽  
Global Patterns ◽  
Open Question ◽  
High Degree

Regenerating animals have the ability to reproduce organs that were originally generated in the embryo and subsequently lost due to injury. Understanding whether the process of regeneration mirrors development is an open question in most regenerative species. Here we take a transcriptomics approach to examine to what extent leg regeneration shows the same temporal patterns of gene expression as leg development in the embryo, in the crustacean Parhyale hawaiensis. We find that leg development in the embryo shows stereotypic temporal patterns of gene expression. In contrast, global patterns of gene expression during leg regeneration show a high degree of variation, related to the physiology of individual animals. A major driver of this variation is the molting cycle. After dissecting the transcriptional signals of individual physiology from regeneration, we obtain temporal signals that mark distinct phases of leg regeneration. Comparing the transcriptional dynamics of development and regeneration we find that, although both processes use largely the same genes, the temporal patterns in which these gene sets are deployed are different and cannot be systematically aligned.

scholarly journals Stochastic asymmetric repartition of lytic machinery in dividing CD8+ T cells generates heterogeneous killing behavior

2020 ◽  
Author(s):  
Fanny Lafouresse ◽  
Romain Jugele ◽  
Sabina Müller ◽  
Marine Doineau ◽  
Valérie Duplan-Eche ◽  
...  
Keyword(s):  
T Cells ◽  
Asymmetric Distribution ◽  
Lytic Granules ◽  
Daughter Cells ◽  
Lytic Function ◽  
Intracellular Vesicles ◽  
Open Question ◽  
High Degree ◽  
Two Sides ◽  
Lytic Compartment

AbstractCytotoxic immune cells are endowed with a high degree of heterogeneity in their lytic function, but how this heterogeneity is generated is still an open question. We therefore investigated if human CD8+ T cells could segregate their lytic components during telophase, using imaging flow cytometry, confocal microscopy and live cell imaging. We show that CD107a+-intracellular vesicles, perforin and granzyme B unevenly segregate in a constant fraction of telophasic cells during each division round. Mathematical modeling posits that unequal lytic molecule inheritance by daughter cells results from the random distribution of lytic granules on the two sides of the cleavage furrow. Finally, we establish that the level of lytic compartment in individual CTL dictates CTL killing capacity. Together, our results show the stochastic asymmetric distribution of effector molecules in dividing CD8+ T cells. They propose uneven mitotic repartition of pre-packaged lytic components as a mechanism generating non-hereditary functional heterogeneity in CTL.

scholarly journals Stochastic asymmetric repartition of lytic machinery in dividing CD8+ T cells generates heterogeneous killing behavior

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Fanny Lafouresse ◽  
Romain Jugele ◽  
Sabina Müller ◽  
Marine Doineau ◽  
Valérie Duplan-Eche ◽  
...  
Keyword(s):  
T Cells ◽  
Asymmetric Distribution ◽  
Lytic Granules ◽  
Daughter Cells ◽  
Lytic Function ◽  
Intracellular Vesicles ◽  
Open Question ◽  
High Degree ◽  
Two Sides ◽  
Lytic Compartment

Cytotoxic immune cells are endowed with a high degree of heterogeneity in their lytic function, but how this heterogeneity is generated is still an open question. We therefore investigated if human CD8+ T cells could segregate their lytic components during telophase, using imaging flow cytometry, confocal microscopy and live cell imaging. We show that CD107a+-intracellular vesicles, perforin and granzyme B unevenly segregate in a constant fraction of telophasic cells during each division round. Mathematical modeling posits that unequal lytic molecule inheritance by daughter cells results from the random distribution of lytic granules on the two sides of the cleavage furrow. Finally, we establish that the level of lytic compartment in individual CTL dictates CTL killing capacity. Together, our results show the stochastic asymmetric distribution of effector molecules in dividing CD8+ T cells. They propose uneven mitotic repartition of pre-packaged lytic components as a mechanism generating non-hereditary functional heterogeneity in CTL.

Investigating active users’ sustained participation in brand communities

Kybernetes ◽  
2019 ◽  
Vol 48 (10) ◽  
pp. 2353-2372
Author(s):  
Ruoyu Liang ◽  
Linghao Zhang ◽  
Wei Guo
Keyword(s):  
Social Capital ◽  
Shared Vision ◽  
Third Party ◽  
Brand Community ◽  
Continuance Intention ◽  
Content Type ◽  
Brand Communities ◽  
Novel Method ◽  
Open Question ◽  
High Degree

Purpose Members’ sustained participation positively influences success of brand community. Although scholars have confirmed the effects of social capital on continuance intention in third-party hosted communities, little work has been done to explore these relationships in context of enterprise-sponsored brand communities, especially, the precursors of active members’ sustained participation in such context is still unclear. Besides, how to recognize active users with high precision and coverage remains an open question. Therefore, this paper aims to propose a novel method to identify active users effectively and investigate the antecedents of their continuance intention from perspective of social capital in enterprise-sponsored brand community. Design/methodology/approach This work established several social networks based on the information of Xiaomi smartphone forum users’ posts and feedbacks. Node centrality (out-degree) analysis was adopted to identify the users with high degree of active in these networks, and then behaviour analysis was performed to exclude the community managers from the group of active users. Finally, a research model was proposed based on the theory of social capital. It was tested by applying partial least squares technique, and the data were collected from a survey of members (n = 327) of Xiaomi forum. Findings The empirical results showed that the proposed method can recognize the active users effectively. Additionally, social tie, identification, trust and shared vision were proved to be significant predictors of active users’ continuance intention in the context of enterprise-sponsored brand community. Originality/value This paper contributes to the information system usage literature and provides opinions regarding how social capital influence active users’ sustained participation in enterprise-sponsored brand community. Besides, this work proposed a novel method to identify active users, which will be useful to assist enterprises to improve their community management.

scholarly journals IX. Bakerian Lecture .—On the law of the pressure of gases between 75 and 150 millimetres of mercury

1902 ◽  
Vol 198 (300-311) ◽  
pp. 417-430 ◽  
Keyword(s):  
Pressure Chamber ◽  
Present Communication ◽  
In Series ◽  
Experimental Errors ◽  
The Law ◽  
Open Question ◽  
High Degree ◽  
Low Pressures ◽  
Published Paper ◽  
Boyle’S Law

In a recently published paper I have examined, with the aid of a new manometer, the behaviour of gases at very low pressures, rising to 1·5 millims. of mercury, with the result that Boyle’s law was verified to a high degree of precision. There is, however, a great gap between the highest pressure there dealt with and that of the atmosphere—a gap which it appeared desirable in some way to bridge over. The sloping manometer, described in the paper referred to, does not lend itself well to the use of much greater pressures, at least if we desire to secure the higher proportional accuracy that should accompany the rise of pressure. The present communication gives the results of observations, by another method, of the law of pressure in gases between 75 millims. and 150 millims. of mercury. It will be seen that for air and hydrogen Boyle’s law is verified to the utmost. In the case of oxygen, the agreement is rather less satisfactory, and the accordance of separate observations is less close. But even here the departure from Boyle’s law amounts only to one part in 4000, and may perhaps be referred to some reaction between the gas and the mercury. In the case of argon too the deviation, though very small, seems to lie beyond the limits of experimental errors. Whether it is due to a real minute departure from Boyle’s law, or to some complication arising out of the conditions of experiment, must remain an open question. In the case of pressures not greatly below atmosphere, the determination with the usual column of mercury read by a cathetometer (after Regnault) is sufficiently accurate. But when the pressure falls to say one-tenth of an atmosphere, the difficulties of this method begin to increase. The guiding idea in the present investigation has been the avoidance of such difficulties by the use of manometric gauges combined in a special manner. The object is to test whether when the volume of a gas is halved its pressure is doubled, and its attainment requires two gauges indicating pressures which are in the ratio of 2:1. To this end we may employ a pair of independent gauges as nearly as possible similar to one another, the similarity being tested by combination in parallel, to borrow an electrical term. When connected below with one reservoir of air and above with another reservoir, or with a vacuum, the two gauges should reach their settings simultaneously, or at least so nearly that a suitable correction may be readily applied. For brevity we may for the present assume precise similarity. If now the two gauges be combined in series , so that the low-pressure chamber of the first communicates with the high-pressure chamber of the second, the combination constitutes a gauge suitable for measuring a doubled pressure.

Turbulent drag reduction and multistage transitions in viscoelastic minimal flow units

2010 ◽  
Vol 647 ◽  
pp. 421-452 ◽  
Author(s):  
LI XI ◽  
MICHAEL D. GRAHAM
Keyword(s):  
Drag Reduction ◽  
The Self ◽  
Sudden Increase ◽  
Minimal Flow ◽  
Mean Flow ◽  
Turbulent Friction ◽  
Minute Amount ◽  
Spatio Temporal ◽  
Open Question ◽  
High Degree

The observation that addition of a minute amount of flexible polymers to fluid reduces turbulent friction drag is well known. However, many aspects of this drag reduction phenomenon are not well understood; in particular, the origin of the maximum drag reduction (MDR) asymptote, a universal upper limit on drag reduction by polymers, remains an open question. This study focuses on the drag reduction phenomenon in the plane Poiseuille geometry in a parameter regime close to the laminar–turbulent transition. By minimizing the size of the periodic simulation box to the lower limit for which turbulence persists, the essential self-sustaining turbulent motions are isolated. In these ‘minimal flow unit’ (MFU) solutions, a series of qualitatively different stages consistent with previous experiments is observed, including an MDR stage where the mean flow rate is found to be invariant with respect to changing polymer-related parameters. Before the MDR stage, an additional transition exists between a relatively low degree (LDR) and a high degree (HDR) of drag reduction. This transition occurs at about 13%–15% of drag reduction and is characterized by a sudden increase in the minimal box size, as well as many qualitative changes in flow statistics. The observation of LDR–HDR transition at less than 15% drag reduction shows for the first time that it is a qualitative transition instead of a quantitative effect of the amount of drag reduction. Spatio-temporal flow structures change substantially upon this transition, suggesting that two distinct types of self-sustaining turbulent dynamics are observed. In LDR, as in Newtonian turbulence, the self-sustaining process involves one low-speed streak and its surrounding streamwise vortices; after the LDR–HDR transition, multiple streaks are present in the self-sustaining structure and complex intermittent behaviour of the streaks is observed. This multistage scenario of LDR–HDR–MDR recovers all key transitions commonly observed and studied at much higher Reynolds numbers.

Sign in / Sign up

Export Citation Format

Share Document