Hemispheric Asymmetry in the Mars Summer Ionosphere at Various Solar Forcing Conditions

2020 ◽  
Author(s):  
Marcin Pilinski ◽  
Laila Andersson ◽  
Ed Thiemann
Keyword(s):  
Magnetic Fields ◽  
Electron Temperature ◽  
Southern Hemisphere ◽  
Polar Regions ◽  
The North ◽  
Northern Summer ◽  
Solar Wind Magnetic Field ◽  
The Difference ◽  
North And South ◽  
Ionospheric Dynamics

<p>The MAVEN satellite has now made two Martian-years of ionosphere-thermosphere (I-T) observations enabling limited studies of seasonal changes in the upper atmosphere. Before examining the ionospheric dynamics associated with space weather, we wish to understand the climatological conditions of the system.  For example, previous studies have revealed the morning electron temperature overshoot as well as a close dependence between electron temperatures and neutral densities in the equatorial regions. In this presentation, we will examine differences in the northern and southern dayside ionosphere during the summer season of each hemisphere. The differences between these two cases will be contrasted with the seasonal dependence at the equator. Differences between the equatorial and polar regions are expected due to (A) differences in neutral scale heights, (B) differences in the solar zenith angle, and (C) the equilibration of I-T coupling due to differences in solar illumination.</p><p>In this work, we present a statistical analysis of MAVEN measurements comparing the north and south summer I-T. We find that when controlling for neutral pressure and latitude, the north and south plasma densities and temperatures are nearly identical below the demagnetization altitude (higher neutral pressures). Above the demagnetization altitude (lower neutral pressures), the southern hemisphere electron densities are higher than those in the northern hemisphere by ~100%. A significantly lower electron temperature is also observed in the south at these lower pressures. Given that the difference in solar EUV (and corresponding neutral heating) is ~20% between the two summer seasons, we postulate that the significantly lower plasma densities (above the demagnetization altitude) in the northern summer are due in part to an increase in ionospheric loss. This loss may be associated with the acceleration of ionospheric particles by the draped magnetic fields at an altitude where ions are not demagnetized. Furthermore, the loss may be diminished in the southern hemisphere where crustal magnetic fields increase the standoff distance to the solar wind magnetic field.</p>

The Difference of Being Overweight or Obese between the North and South of China

2020 ◽  
Author(s):  
Daisheng Tang ◽  
Tao Bu ◽  
Yahong Liu ◽  
Xuefan Dong
Keyword(s):  
Logistic Regression ◽  
Dietary Patterns ◽  
Odds Ratio ◽  
Nutrition Survey ◽  
High Intake ◽  
Related Information ◽  
The North ◽  
Health Related ◽  
The Difference ◽  
North And South

Abstract Objectives: The geographical environment, dietary culture, food patterns, and obesity rates are substantially different between the North and South of China. Determining the geographical distribution and local dietary patterns involved in being overweight or obese is useful for designing intervention strategies. Methods: Residents between 18 and 65 years old (n=10,863) from 11 Chinese provinces (five Northern provinces and six Southern provinces) were selected to compare dietary patterns, BMI, and health-related information from the China Health and Nutrition Survey packages in 2011. Linear and logistic regression analyses were performed to assess the strength of the association among geographic variables, the obesity problem, and dietary patterns. Results: The overall prevalence of being overweight or obese was 10.51% higher in the North than in the South. Northern dietary patterns feature a high intake of wheat and soybeans, whereas Southern dietary patterns feature a high intake of rice, vegetables, meat, and poultry. The estimated coefficient of regional variables surrounding dietary score is 1.494; surrounding the odds ratio for being overweight is 1.681, whereas surrounding the odds ratio for obesity is 2.035. Multivariate logistic regression including both the variable of South–North areas and Northern dietary patterns showed a significant correlation with being overweight or obese. Conclusion: Northern areas and their local dietary patterns are more likely to contribute to being overweight or obese. These findings provide support for tracking the progression of obesity, epidemics, and policies that target the ‘‘obesogenic’’ environment, promoting opportunities for persons to access healthy dietary patterns and nutritional balance.

scholarly journals Measuring the local dark matter density with LAMOST DR5 and Gaia DR2

2020 ◽  
Vol 495 (4) ◽  
pp. 4828-4844 ◽  
Author(s):  
Rui Guo ◽  
Chao Liu ◽  
Shude Mao ◽  
Xiang-Xiang Xue ◽  
R J Long ◽  
...  
Keyword(s):  
Dark Matter ◽  
Azimuthal Angle ◽  
Matter Density ◽  
Dwarf Stars ◽  
Dark Matter Density ◽  
The North ◽  
Vertical Data ◽  
Data Release ◽  
The Difference ◽  
North And South

ABSTRACT We apply the vertical Jeans equation to the kinematics of Milky Way stars in the solar neighbourhood to measure the local dark matter density. More than 90 000 G- and K-type dwarf stars are selected from the cross-matched sample of LAMOST (Large Sky Area Multi-Object Fibre Spectroscopic Telescope) fifth data release and Gaia second data release for our analyses. The mass models applied consist of a single exponential stellar disc, a razor thin gas disc, and a constant dark matter density. We first consider the simplified vertical Jeans equation that ignores the tilt term and assumes a flat rotation curve. Under a Gaussian prior on the total stellar surface density, the local dark matter density inferred from Markov chain Monte Carlo simulations is $0.0133_{-0.0022}^{+0.0024}\ {\rm M}_{\odot }\, {\rm pc}^{-3}$. The local dark matter densities for subsamples in an azimuthal angle range of −10° < ϕ < 5° are consistent within their 1σ errors. However, the northern and southern subsamples show a large discrepancy due to plateaux in the northern and southern vertical velocity dispersion profiles. These plateaux may be the cause of the different estimates of the dark matter density between the north and south. Taking the tilt term into account has little effect on the parameter estimations and does not explain the north and south asymmetry. Taking half of the difference of σz profiles as unknown systematic errors, we then obtain consistent measurements for the northern and southern subsamples. We discuss the influence of the vertical data range, the scale height of the tracer population, the vertical distribution of stars, and the sample size on the uncertainty of the determination of the local dark matter density.

The growth pattern of the African tortoise Geochelone pardalis and other chelonians

1999 ◽  
Vol 77 (2) ◽  
pp. 181-193 ◽  
Author(s):  
Adrian Hailey ◽  
Ian M Coulson
Keyword(s):  
Growth Pattern ◽  
High Growth ◽  
Growth Patterns ◽  
Growth Rings ◽  
Frequency Distributions ◽  
The North ◽  
Body Sizes ◽  
Biased Sex Ratio ◽  
The Difference ◽  
North And South

Growth rings were measured in dead African leopard tortoises, Geochelone pardalis, collected in the seasonal tropics of Zimbabwe over an 11-year period. A series of Ford-Walford plots using growth measured from annuli showed that growth fitted a logistic by mass curve best, logistic by length and Gompertz curves less well, and a Bertalanffy curve least well. The Bertalanffy curve, often fitted to growth of chelonians, is characterised by particularly high growth rates of juveniles compared with larger individuals. It is suggested that this growth pattern is likely to be found in species showing a marked decrease in diet quality with size. This hypothesis is supported by a review of growth patterns in chelonians: Bertalanffy curves are associated with an omnivorous (and thus potentially variable) diet and other growth patterns with an obligate carnivorous or herbivorous diet. Geochelone pardalis in Zimbabwe showed significant sexual size dimorphism, the mean asymptotic mass of females being 1.7 times that of males, unlike populations with larger body sizes to the north and south. Annual survival estimated from age-frequency distributions was significantly higher in males (0.80) than in females (0.72), the difference being sufficient to account for the male-biased sex ratio of live animals.

scholarly journals Variation in Drosophila sensory bristle number at ‘Evolution Canyon’

2002 ◽  
Vol 80 (3) ◽  
pp. 215-223 ◽  
Author(s):  
RICHARD F. LYMAN ◽  
EVIATAR NEVO ◽  
TRUDY F. C. MACKAY
Keyword(s):  
Environmental Gradients ◽  
Extreme Environments ◽  
Geographic Scale ◽  
Thermal Environments ◽  
The North ◽  
Relative Contribution ◽  
Bristle Number ◽  
Evolution Canyon ◽  
The Difference ◽  
North And South

‘Evolution Canyon’ on Mount Carmel, Israel, displays highly contrasting physical and biotic environments on a micro-geographic scale, and is a natural laboratory for investigating genetic responses to variable and extreme environments across species. Samples of Drosophila melanogaster and D. simulans were collected from three sites each on the north- and south-facing slopes of the canyon along altitudinal transects, and one site on the valley floor. Numbers of abdominal and sternopleural sensory bristles were recorded for each of these subpopulations in three thermal environments. In D. simulans, sternopleural bristle number exhibited micro-geographic differentiation between the north- and south-facing slopes, while abdominal bristle number was stable across subpopulations. In D. melanogaster, the magnitudes of the difference in mean sternopleural bristle number between the north- and south-facing slopes and of mean abdominal bristle number along the altitudinal gradients were both conditional on rearing temperature. Thus, the pattern of genetic variation between sites was consistent with underlying heterogeneity of genetic mechanisms for response to the same environmental gradients between traits and sibling species. In contrast, the genetic architecture of bristle number at the level of variation within populations was very similar between species for the same bristle trait, although the two traits differed in the relative contribution of genotype by temperature and genotype by sex interaction.

scholarly journals Analysis of Screening Results of 1012 Sperm Donors in China: A Retrospective Cohort Study of Geographic Differences in Semen Quality

2021 ◽  
Author(s):  
Qian-Cheng Zhao ◽  
Zhe Zhang ◽  
Lian-Ming Zhao ◽  
Zhen-Feng Deng ◽  
Jiang-Man Gao ◽  
...  
Keyword(s):  
Semen Quality ◽  
Sperm Concentration ◽  
Strong Relationship ◽  
Male Reproduction ◽  
Geographical Differences ◽  
Sperm Donors ◽  
The North ◽  
Significant Difference ◽  
The Difference ◽  
North And South

Abstract Male reproductive health has become a concern in public health, and semen quality is essential to male reproduction. To investigate the geographical differences in semen quality of sperm donors from the north and south of China, a total of 1012 sperm donors from all over China were enrolled in this work, which were divided by their residential latitude. There were statistically significant differences in sperm concentration among men from different latitudes in China(P=0.04). The sperm concentrations of people from 18°-27° north latitude were lower than those from 36°-45°, and 45°-54° (median 131, 134, 146, respectively, P=0.021[18°-27° vs. 36°-45°] and P=0.01[18°-27° vs. 45°-54°]). It was further confirmed when the samples were re-divided into 2 groups (typically north and south) that contains 667 samples. The analysis also showed a significant difference in terms of the regions to which the samples belonged (the median of the north is 134; the median of the south is 125; P =0.015). Although other sperm parameters don’t show significant change with latitude, some of them possess a strong relationship with sperm concentration (r=-0.19364, P<0.001). Specifically, we suppose that environmental pollution and mental stress due to increased population may be the main factors in the difference.

Surveying terrestrial magnetism in time and space

2005 ◽  
Vol 32 (2) ◽  
pp. 346-360 ◽  
Author(s):  
Anita McConnell
Keyword(s):  
Polar Regions ◽  
Horizontal Force ◽  
Magnetic Pole ◽  
Compass Direction ◽  
The North ◽  
Magnetic Variation ◽  
Magnetic Meridian ◽  
Magnetic Poles ◽  
North And South ◽  
Over Time

Charts marked with the lines of magnetic variation have been published since Halley's Atlantic chart of 1701. It was already known that the location of the magnetic poles shifted over time, and that the north and south poles were not diametrically opposite. As more seafarers penetrated the Southern Ocean, isogons on the charts were extended southwards with greater confidence. At sea variation was measured by comparing compass direction with the Sun's midday shadow. In polar regions, where horizontal force is too weak to attract a compass needle, the location of the pole was sought by observing the inclination of a dip needle swinging in the magnetic meridian, which would hang vertically at the pole. The Fox dip circle, developed in 1834, was the first instrument capable of measuring dip and intensity at sea, and allowed James Clark Ross to predict the location of the South Magnetic Pole. In 1902 Discovery's crew landed an observatory ashore, but a trek on to the plateau failed to reach the magnetic pole. Success came in 1909 during Shackleton's Nimrod expedition, when T. Edgeworth David's party reached the zone of maximum dip. Over the following years data from photographic magnetometers recording declination, vertical and horizontal intensity were routinely made at the various national bases round Antarctica; they contributed to our knowledge of the Earth's internal magnetism and on the solar influences.

Genetic differentiation and inversion clines in Indian natural populations of Drosophila melanogaster

Genome ◽  
1991 ◽  
Vol 34 (4) ◽  
pp. 618-625 ◽  
Author(s):  
Aparup Das ◽  
B. N. Singh
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Differentiation ◽  
Natural Populations ◽  
The South ◽  
The North ◽  
Chromosome Inversions ◽  
The Difference ◽  
And Inversion ◽  
First Time ◽  
North And South

To study the genetic differentiation and inversion clines in Indian natural populations of Drosophila melanogaster, 14 natural populations (6 from the north and 8 from the south) were screened for chromosome inversions. The chromosomal analysis revealed the presence of 23 paracentric inversions, which include 4 common cosmopolitan, 4 rare cosmopolitan, 2 recurrent endemic, and 13 unique endemic (new inversions detected for the first time) inversions. The difference in karyotype frequencies between populations from the north and south were highly significant and the level of inversion heterozygosity was higher in populations from the south. Statistically significant negative correlations were found between each of the four common cosmopolitan inversions and latitude. These findings are in accord with results from other worldwide geographic regions and show that Indian populations of D. melanogaster have undergone considerable genetic differentiation at the level of inversion polymorphism.Key words: Drosophila melanogaster, Indian natural populations, chromosome inversions, genetic differentiation, north–south clines.

scholarly journals Trends of halon gases in polar firn air: implications for their emission distributions

2005 ◽  
Vol 5 (8) ◽  
pp. 2055-2064 ◽  
Author(s):  
C. E. Reeves ◽  
W. T. Sturges ◽  
G. A. Sturrock ◽  
K. Preston ◽  
D. E. Oram ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Ice Core ◽  
Atmospheric Model ◽  
Polar Regions ◽  
Emission Rates ◽  
Atmospheric Concentration ◽  
Depth Profiles ◽  
Devon Island ◽  
The North ◽  
Indirect Evaluation

Abstract. Four halons (H-1301, H-1211, H-2402 and H-1202) have been measured in air samples collected from polar firn from Dome Concordia (Dome C), Antarctica, from Devon Island, Canada and the North Greenland Ice Core Project (NGRIP) site, Greenland. H-2402 and H-1202 are reported for the first time in firn air. The depth profiles show the concentrations of all four halons to be close to zero (i.e. below the detection limit of 0.001 ppt) at the base of the firn thus demonstrating their entirely anthropogenic origin. This is the first evidence of this for H-2402 and H-1202. A 2-D atmospheric model was run with emissions previously derived using archive air measurements from the southern hemisphere mid-latitudes to produce historical trends in atmospheric concentrations at the firn sites, which were then input into a firn diffusion model to produce concentration depth profiles for comparison with the firn measurements. This comparison provides an evaluation of the model-derived atmospheric concentration histories in both hemispheres and thus an indirect evaluation of the emission rates and distributions used in the atmospheric model. Atmospheric concentration trends produced using global emissions previously determined from measurements at Cape Grim are found to be consistent with the firn data from the southern hemisphere. Further emissions of H-1202 in recent years (late 1980s onwards) are likely to have come from latitudes mostly south of 40° N, but emissions prior to that may have come from further north. Emissions of H-1211 may also have shifted to latitudes south of 40° N during the late 1980s. Following comparison of the atmospheric model output with the firn data, modelled atmospheric trends of total organic bromine in the form of halons were derived for both polar regions.

Explaining globally inhomogeneous future changes in monsoons using simple moist energy diagnostics

2021 ◽  
pp. 1-45
Author(s):  
Rodrigo J. Bombardi ◽  
William R. Boos
Keyword(s):  
North America ◽  
South America ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Southern Africa ◽  
Rainy Season ◽  
Coupled Model ◽  
Summer Precipitation ◽  
The North ◽  
The Difference

AbstractThis study examines the annual cycle of monsoon precipitation simulated by models from the Coupled Model Intercomparison Project phase 6 (CMIP6), then uses moist energy diagnostics to explain globally inhomogeneous projected future changes. Rainy season characteristics are quantified using a consistent method across the globe. Model bias is shown to include rainy season onsets tens of days later than observed in some monsoon regions (India, Australia, and North America) and overly large summer precipitation in others (North America, South America, and southern Africa). Projected next-century changes include rainy season lengthening in the two largest Northern Hemisphere monsoon regions (South Asia and central Sahel) and shortening in the two largest Southern Hemisphere regions (South America and southern Africa). Changes in the North American and Australian monsoons are less coherent across models. To understand these changes, relative moist static energy (MSE) is defined as the difference between local and tropical-mean surface air MSE. Future changes in relative MSE in each region correlate well with onset and demise date changes. Furthermore, Southern Hemisphere regions projected to undergo rainy season shortening are spanned by an increasing equator-to-pole MSE gradient, suggesting their rainfall will be increasingly inhibited by fluxes of dry extratropical air; Northern Hemisphere regions with projected lengthening of rainy seasons undergo little change in equator-to-pole MSE gradient. Thus, although model biases raise questions on the reliability of some projections, these results suggest that globally inhomogeneous future changes in monsoon timing may be understood through simple measures of surface air MSE.

scholarly journals Pinnacles on the surface of the comet 67P/Churyumov-Gerasimenko: regional distribution and morphology

2019 ◽  
Author(s):  
S S Krasilnikov ◽  
Y V Skorov ◽  
A T Basilevsky ◽  
S F Hviid ◽  
U Mall ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Regional Distribution ◽  
Surface Erosion ◽  
Maximum Height ◽  
Minimum Thickness ◽  
Mean Values ◽  
The North ◽  
Evolutionary Changes ◽  
Nucleus Surface ◽  
North And South

Abstract Pinnacles are local topographic promontories of different shapes considered to be formed due to uneven surface erosion. In the case of comets, areal changes in the degree of erosion could be related to inhomogeneities of the nucleus. However, the amount of solar radiation and the thermal gradient is different across the orbit for geomorphological regions, which can result in different erosion and shape for a similar composition among two differently illuminated areas. Therefore, a study of the areal distribution of pinnacles on the nucleus surface and their morphology may help to understand the structure and properties of the nucleus material. We mapped 166 pinnacles on the comet nucleus surface of 67P/Churyumov-Gerasimenko. About a third of them have planimetrically rounded shape (rounded pinnacles) and the rest are planimetrically elongated (local ridges). In the southern hemisphere, number of both round pinnacles and local ridges is larger than in the northern hemisphere. This difference possibly indicates the higher effectiveness of the pinnacles’ formation in the southern hemisphere. At the same time the mean values of the measured parameters, including the height, show no statistically reliable difference between the north and south. We found that the maximum height of the pinnacles is about a hundred meters. Suggesting that they have been formed by sublimational erosion, this value allows estimating the minimum thickness of the eroded material and thus the degree of the evolutionary changes of the nucleus. In our future study, we will model pinnacles formation based on the here presented analysis of observations.

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