Abstract: Collapsible soils like loess comprise an important category of problematic soils for construction purposes and sustainable development. As a result, research on both geological and geotechnical aspects of this type of soil have been in progress for decades. However, considerable natural variability in physical properties of in-situ loess strata even in a single block sample challenges the fundamental laboratory investigations. The reason behind this is that it is somehow impossible to remove the effect of a specific factor like void ratio from fair comparisons to come with a reliable conclusion. In order to cope with this limitation, two types of artificially made dispersive and calcareous loess are introduced which can be easily reproduced in any soil mechanics laboratory provided that all its compositions are known and controlled. The collapse potential is explored for a variety of soil water salinity and lime content and comparisons are made against the natural soil behavior. Trends are reported for the influence of pore water salinity on collapse potential under different osmotic flow conditions. The most important advantage of artificial loess is the ease of controlling cementing agent content like calcite or dispersive potential for studying their influence on mechanical soil behavior.
Abstract: Magnetic susceptibility (χ) is operational to identify of late quaternary glacial-interglacial cycles in loess-paleosol sequences. It is well accepted that many loess-paleosol sequences bear witness to cold-dry/warm-humid periods, well known as glacial-interglacial cycles, respectively. For this study, loess-paleosol sequence of north-east of Iran was magnetically investigated. The study area is situated at about 8 km away of Neka city, on the main road of Sari-Behshahr, in Mazandaran Province, north of Iran. The youngest deposits of study area are the late Quaternary wind-blown accumulations. In this study, the total number of 117 samples was collected from loess-paleosols units. After that, the natural remnant magnetization (NRM) and magnetic susceptibility (MS) of the samples were measured. Variation of MS of more than 110 loess samples was plotted to reveal the correlation of the MS and paleoclimatic changes. This study aims reconstruction of climatic changes (glacial-interglacial and stadials-interstadials cycles). To confirm our results we compared MS (χ) and the curves of other investigations in paleoclimatology. This correspondence abled us to recognize worldly events in the study area such as: Younger Dryas, the Last Glacial Maximum (LGM), deglaciation of Northern Hemisphere etc. The obtained magnetic data indicate that during almost 50 ka, at least two glacial-interglacial periods occurred in north-east of Iran. Further, variation of χ values revealed short period of climatically cycles known as stadials-interstadials. We recognized 4 stadials and a single stadial as colder sub-periods for S0 (recently soil-paleosol) and S2 (lower paleosol), respectively, Moreover, we recognized 6 warmer sub-periods (interstadials) for L1 (upper loess) and one interstadial L2 (lower loess).
Abstract: The objectives of the research are to find the basic engineering properties of lateritic soil and to predict the impact on community members who live nearby the excavation pits in the area of Amphur Pak Thor, Ratchaburi Province in the western area of Thailand. The research was conducted by collecting soil samples from four excavation pits for basic engineering properties, testing and collecting questionnaire data from 120 community members who live nearby the excavation pits, and applying statistical analysis. The results found that the basic engineering properties of lateritic soil can be classified into silt soil type which is cohesionless as the loess or collapsible soil which is not suitable to be used for a pavement structure for commuting highway because it could lead to structural and functional failure in the long run. In terms of opinion from community members toward the impact, the highest impact was on the dust from excavation activities. The prediction from the logistic regression in terms of impact on community members was at 84.32 which can be adapted and applied onto other areas with the same context as a guideline for risk prevention and risk communication since it could impact the infrastructures and also impact the health of community members.
Abstract: One of the biggest challenges in nonparametric
regression is the curse of dimensionality. Additive models are known
to overcome this problem by estimating only the individual additive
effects of each covariate. However, if the model is misspecified, the
accuracy of the estimator compared to the fully nonparametric one
is unknown. In this work the efficiency of completely nonparametric
regression estimators such as the Loess is compared to the estimators
that assume additivity in several situations, including additive and
non-additive regression scenarios. The comparison is done by
computing the oracle mean square error of the estimators with regards
to the true nonparametric regression function. Then, a backward
elimination selection procedure based on the Akaike Information
Criteria is proposed, which is computed from either the additive or
the nonparametric model. Simulations show that if the additive model
is misspecified, the percentage of time it fails to select important
variables can be higher than that of the fully nonparametric approach.
A dimension reduction step is included when nonparametric estimator
cannot be computed due to the curse of dimensionality. Finally, the
Boston housing dataset is analyzed using the proposed backward
elimination procedure and the selected variables are identified.
Abstract: Twenty seven tektites from the Wenchang area, Hainan
province (south China) and five tektites from the Khon Kaen area
(northeast Thailand) were analyzed for major and trace element
contents and Rb-Sr isotopic compositions. All the samples studied are
splash-form tektites. Tektites of this study are characterized by high
SiO2 contents ranging from 71.95 to 74.07 wt% which is consistent
with previously published analyses of Australasian tektites. The trace
element ratios Ba/Rb (avg. 3.89), Th/Sm (avg. 2.40), Sm/Sc (avg.
0.45), Th/Sc (avg. 0.99) and the rare earth elements (REE) contents of
tektites of this study are similar to the average upper continental crust.
Based on the chemical composition, it is suggested that tektites in this
study are derived from similar parental material and are similar to the
post-Archean upper crustal rocks. The major and trace element
abundances of tektites analyzed indicate that the parental material of
tektites may be a terrestrial sedimentary deposit. The tektites from the
Wenchang area, Hainan Island have high positive εSr(0)
values-ranging from 184.5~196.5 which indicate that the parental
material for these tektites have similar Sr isotopic compositions to old
terrestrial sedimentary rocks and they were not dominantly derived
from recent young sediments (such as soil or loess). Based on Rb-Sr
isotopic data, it has been suggested by Blum (1992) [1]that the
depositional age of sedimentary target materials is close to 170Ma
(Jurassic). According to the model suggested by Ho and Chen
(1996)[2], mixing calculations for various amounts and combinations
of target rocks have been carried out. We consider that the best fit for
tektites from the Wenchang area is a mixture of 47% shale, 23%
sandstone, 25% greywacke and 5% quartzite, and the other tektites
from Khon Kaen area is a mixture of 46% shale, 2% sandstone, 20%
greywacke and 32% quartzite.
Abstract: We measured the major and trace element contents
and Rb-Sr isotopic compositions of 12 tektites from the Maoming
area, Guandong province (south China). All the samples studied are
splash-form tektites which show pitted or grooved surfaces with
schlieren structures on some surfaces. The trace element ratios Ba/Rb
(avg. 4.33), Th/Sm (avg. 2.31), Sm/Sc (avg. 0.44), Th/Sc (avg. 1.01) ,
La/Sc (avg. 2.86), Th/U (avg. 7.47), Zr/Hf (avg. 46.01) and the rare
earth elements (REE) contents of tektites of this study are similar to the
average upper continental crust. From the chemical composition, it is
suggested that tektites in this study are derived from similar parental
terrestrial sedimentary deposit which may be related to post-Archean
upper crustal rocks. The tektites from the Maoming area have high
positive εSr(0) values-ranging from 176.9~190.5 which indicate that
the parental material for these tektites have similar Sr isotopic
compositions to old terrestrial sedimentary rocks and they were not
dominantly derived from recent young sediments (such as soil or
loess). The Sr isotopic data obtained by the present study support the
conclusion proposed by Blum et al. (1992)[1] that the depositional age
of sedimentary target materials is close to 170Ma (Jurassic). Mixing
calculations based on the model proposed by Ho and Chen (1996)[2]
for various amounts and combinations of target rocks indicate that the
best fit for tektites from the Maoming area is a mixture of 40% shale,
30% greywacke, 30% quartzite.
Abstract: The field research was carried out at the Látókép AGTC KIT research area of the University of Debrecen in Eastern-Hungary, on the area of the aeolain loess of the Hajdúság. We examined the effects of the sowing time on the phytopathogenic characteristics and yield production by applying various fertilizer treatments on two different sunflower genotypes (NK Ferti, PR64H42) in 2012 and 2013. We applied three different sowing times (early, optimal, late) and two different treatment levels of fungicides (control = no fungicides applied, double fungicide protection).
During our investigations, the studied cropyears were of different sowing time optimum in terms of yield amount (2012: early, 2013: average). By Pearson’s correlation analysis, we have found that delaying the sowing time pronouncedly decreased the extent of infection in both crop years (Diaporthe: r=0.663**, r=0.681**, Sclerotinia: r=0.465**, r=0.622**). The fungicide treatment not only decreased the extent of infection, but had yield increasing effect too (2012: r=0.498**, 2013: r=0.603**). In 2012, delaying of the sowing time increased (r=0.600**), but in 2013, it decreased (r= 0.356*) the yield amount.
Abstract: Thousands of masters athletes participate
quadrennially in the World Masters Games (WMG), yet this cohort
of athletes remains proportionately under-investigated. Due to a
growing global obesity pandemic in context of benefits of physical
activity across the lifespan, the BMI trends for this unique population
was of particular interest. The nexus between health, physical
activity and aging is complex and has raised much interest in recent
times due to the realization that a multifaceted approach is necessary
in order to counteract the obesity pandemic. By investigating age
based trends within a population adhering to competitive sport at
older ages, further insight might be gleaned to assist in understanding
one of many factors influencing this relationship.BMI was derived
using data gathered on a total of 6,071 masters athletes (51.9% male,
48.1% female) aged 25 to 91 years ( =51.5, s =±9.7), competing at
the Sydney World Masters Games (2009). Using linear and loess
regression it was demonstrated that the usual tendency for prevalence
of higher BMI increasing with age was reversed in the sample. This
trend in reversal was repeated for both male and female only sub-sets
of the sample participants, indicating the possibility of improved
prevalence of BMI with increasing age for both the sample as a
whole and these individual sub-groups.This evidence of improved
classification in one index of health (reduced BMI) for masters
athletes (when compared to the general population) implies there are
either improved levels of this index of health with aging due to
adherence to sport or possibly the reduced BMI is advantageous and
contributes to this cohort adhering (or being attracted) to masters
sport at older ages.
Abstract: Non-saturated soils that while saturation greatly
decrease their volume, have sudden settlement due to increasing
humidity, fracture and structural crack are called loess soils. Whereas
importance of civil projects including: dams, canals and
constructions bearing this type of soil and thereof problems, it is
required for carrying out more research and study in relation to loess
soils. This research studies shear strength parameters by using
grading test, Atterberg limit, compression, direct shear and
consolidation and then effect of using cement and lime additives on
stability of loess soils is studied. In related tests, lime and cement are
separately added to mixed ratios under different percentages of soil
and for different times the stabilized samples are processed and effect
of aforesaid additives on shear strength parameters of soil is studied.
Results show that upon passing time the effect of additives and
collapsible potential is greatly decreased and upon increasing
percentage of cement and lime the maximum dry density is
decreased; however, optimum humidity is increased. In addition,
liquid limit and plastic index is decreased; however, plastic index
limit is increased. It is to be noted that results of direct shear test
reveal increasing shear strength of soil due to increasing cohesion
parameter and soil friction angle.
Abstract: Whilst there is growing evidence that activity
across the lifespan is beneficial for improved health, there are
also many changes involved with the aging process and
subsequently the potential for reduced indices of health. The
nexus between health, physical activity and aging is complex
and has raised much interest in recent times due to the
realization that a multifaceted approached is necessary in
order to counteract a growing obesity epidemic. By
investigating age based trends within a population adhering to
competitive sport at older ages, further insight might be
gleaned to assist in understanding one of many factors
influencing this relationship.
BMI was derived using data gathered on a total of 6,071
masters athletes (51.9% male, 48.1% female) aged 25 to 91
years ( =51.5, s =±9.7), competing at the Sydney World
Masters Games (2009). Using linear and loess regression it
was demonstrated that the usual tendency for prevalence of
higher BMI increasing with age was reversed in the sample.
This trend in reversal was repeated for both male and female
only sub-sets of the sample participants, indicating the
possibility of improved prevalence of BMI with increasing
age for both the sample as a whole and these individual subgroups.
This evidence of improved classification in one index of
health (reduced BMI) for masters athletes (when compared to
the general population) implies there are either improved
levels of this index of health with aging due to adherence to
sport or possibly the reduced BMI is advantageous and
contributes to this cohort adhering (or being attracted) to
masters sport at older ages. Demonstration of this
proportionately under-investigated World Masters Games
population having an improved relationship between BMI and
increasing age over the general population is of particular
interest in the context of the measures being taken globally to
curb an obesity epidemic.