scholarly journals Novel ultra nanoindentation method with extremely low thermal drift: Principle and experimental results

2009 ◽  
Vol 24 (3) ◽  
pp. 873-882 ◽  
Author(s):  
J. Nohava ◽  
N.X. Randall ◽  
N. Conté
Keyword(s):  
Thin Films ◽  
High Resolution ◽  
Thermal Stabilization ◽  
Maximum Load ◽  
Experimental Results ◽  
Thermal Drift ◽  
The Past ◽  
Short Period ◽  
Low Levels

Despite active development over the past 15 years, contemporary nanoindentation methods still suffer serious drawbacks, particularly long thermal stabilization and thermal drift, which limit the duration of the measurements to only a short period of time. The presented work introduces a novel ultra nanoindentation method that uses loads from the μN range up to 50 mN, is capable of performing long-term stable measurements, and has negligible frame compliance. The method is based on a novel patented design, which uses an active top referencing system. Several materials were used to demonstrate the performance of the method. The measurements with hold at maximum load confirm extremely low levels of instrument thermal drift. The presented Ultra Nanoindentation Tester opens new possibilities for testing thin films and long-term testing, including creep of polymers at high resolution without the need of long thermal stabilization.

scholarly journals Heatwaves in Kenya 1987–2016: Facts from CHIRTS High Resolution Satellite Remotely Sensed and Station Blended Temperature Dataset

Atmosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 37
Author(s):  
Martial Amou ◽  
Amatus Gyilbag ◽  
Tsedale Demelash ◽  
Yinlong Xu
Keyword(s):  
High Resolution ◽  
Adaptation Strategies ◽  
Reference Period ◽  
The West ◽  
Tana River ◽  
Short Period ◽  
The World ◽  
Northern Side ◽  
Data Source

As global temperatures continue to rise unabated, episodes of heat-related catastrophes across the world have intensified. In Kenya, heatwave phenomena and their associated impacts are ignored and neglected due to several reasons, including unreliable and inconsistent weather datasets and heatwave detection metrics. Based on CHIRTS satellite infrared estimates and station blended temperature, this study investigated the spatiotemporal distribution of the heatwave events over Kenya during 1987–2016 using the Heatwave Magnitude Index daily (HWMId). The results showed that contrary to the absence of heatwave records in official national and international disaster database about Kenya, the country experienced heatwaves ranging from less severe (normal) to deadly (super-extreme) between 1987 and 2016. The most affected areas were located in the eastern parts of the country, especially in Garissa and Tana River, and in the west-northern side around the upper side of Turkana county. It was also found that the recent years’ heatwaves were more severe in magnitude, duration, and spatial extent. The highest magnitude of the heatwaves was recorded in 2015 (HWMId = 22.64) while the average over the reference period is around 6. CHIRTS and HWMId were able to reveal and capture most critical heatwave events over the study period. Therefore, they could be used respectively as data source and detection metrics, for heatwaves disaster emergency warning over short period as well as for long-term projection to provide insight for adaptation strategies.

scholarly journals The Duration of Breastfeeding and Its Association with Metabolic Syndrome among Obese Children

2015 ◽  
Vol 2015 ◽  
pp. 1-4 ◽  
Author(s):  
Renata Yakubov ◽  
Erez Nadir ◽  
Roni Stein ◽  
Adi Klein-Kremer
Keyword(s):  
Metabolic Syndrome ◽  
Statistical Significance ◽  
Breastfeeding Duration ◽  
Obese Children ◽  
The Metabolic Syndrome ◽  
Short Period ◽  
Study Population ◽  
Low Levels ◽  
Duration Of Breastfeeding

Objective. The objective of this study was to evaluate whether duration of breastfeeding is associated with a lower prevalence of metabolic syndrome in obese children.Methods. A retrospective analysis of obese children aged 3 to 18 years followed at a pediatric outpatient clinic at a single center between the years 2008 and 2012. The children were divided according to their breastfeeding duration: no breastfeeding, a short period of breastfeeding, and a long term breastfeeding. Also, they were divided into metabolic and nonmetabolic syndrome groups, based on physical examination and laboratory tests.Results. Out of 4642 children who visited the clinic, 123 were obese and were included in the study. About half of them matched the metabolic syndrome criteria. There was no correlation between the prevalence of metabolic syndrome and the duration of breastfeeding. Hypertension, abnormal low levels of HDL, high levels of HbA1c, and high fasting triglyceride levels were very common in our study population, yet no statistical significance was noted among the different breastfeeding groups.Conclusion. In this study, breastfeeding was not associated with a reduced risk for metabolic syndrome, compared with formula feeding, in children who are obese.

scholarly journals Reconstruction of a continuous high-resolution CO<sub>2</sub> record over the past 20 million years

2011 ◽  
Vol 7 (4) ◽  
pp. 1459-1469 ◽  
Author(s):  
R. S. W. van de Wal ◽  
B. de Boer ◽  
L. J. Lourens ◽  
P. Köhler ◽  
R. Bintanja
Keyword(s):  
High Resolution ◽  
Sea Level ◽  
Northern Hemisphere ◽  
Climate Models ◽  
Ice Core ◽  
Co2 Concentration ◽  
Temperature Record ◽  
Absorption Bands ◽  
The Past

Abstract. The gradual cooling of the climate during the Cenozoic has generally been attributed to a decrease in CO2 concentration in the atmosphere. The lack of transient climate models and, in particular, the lack of high-resolution proxy records of CO2, beyond the ice-core record prohibit, however, a full understanding of, for example, the inception of the Northern Hemisphere glaciation and mid-Pleistocene transition. Here we elaborate on an inverse modelling technique to reconstruct a continuous CO2 series over the past 20 million year (Myr), by decomposing the global deep-sea benthic δ18O record into a mutually consistent temperature and sea level record, using a set of 1-D models of the major Northern and Southern Hemisphere ice sheets. We subsequently compared the modelled temperature record with ice core and proxy-derived CO2 data to create a continuous CO2 reconstruction over the past 20 Myr. Results show a gradual decline from 450 ppmv around 15 Myr ago to 225 ppmv for mean conditions of the glacial-interglacial cycles of the last 1 Myr, coinciding with a gradual cooling of the global surface temperature of 10 K. Between 13 to 3 Myr ago there is no long-term sea level variation caused by ice-volume changes. We find no evidence of change in the long-term relation between temperature change and CO2, other than the effect following the saturation of the absorption bands for CO2. The reconstructed CO2 record shows that the Northern Hemisphere glaciation starts once the long-term average CO2 concentration drops below 265 ppmv after a period of strong decrease in CO2. Finally, only a small long-term decline of 23 ppmv is found during the mid-Pleistocene transition, constraining theories on this major transition in the climate system. The approach is not accurate enough to revise current ideas about climate sensitivity.

scholarly journals A General Origin for Multiplanetary Systems With Significantly Misaligned USP Planets

2021 ◽  
Vol 162 (6) ◽  
pp. 242
Author(s):  
L. Brefka ◽  
J. C. Becker
Keyword(s):  
Perturbation Theory ◽  
The Past ◽  
Short Period ◽  
Mutual Inclination ◽  
Dynamical Parameters ◽  
Orbital Periods ◽  
Star Ages ◽  
The Relationship ◽  
Host Stars

Abstract Ultra-short-period (USP) planets are exoplanets that have orbital periods of less than one day and are unique because they orbit inside the nominal magnetic truncation gap of their host stars. In some cases, USP planets have also been observed to exhibit unique dynamical parameters such as significant misalignments in inclination angle with respect to nearby planets. In this paper, we explore how the geometry of a multiplanet system hosting a USP planet can be expected to evolve as a star ages. In particular, we explore the relationship between the mutual inclination of the USP planet and the quadrupole moment (J 2) of the host star. We use secular perturbation theory to predict the past evolution of the example TOI-125 system, and then confirm the validity of our results using long-term N-body simulations. Through investigating how the misalignment between the candidate USP planet and the three other short-period planets in the TOI-125 system arose, we intend to derive a better understanding of the population of systems with misaligned USP planets and how their observed parameters can be explained in the context of their dynamical histories.

The Production and Application of Chemical Fertilizers in China

1975 ◽  
Vol 64 ◽  
pp. 712-729 ◽  
Author(s):  
Kang Chao
Keyword(s):  
Growth Rate ◽  
Chemical Fertilizer ◽  
The Self ◽  
Chemical Fertilizers ◽  
Power Struggles ◽  
The Past ◽  
Fertilizer Industry ◽  
Self Reliance ◽  
Short Period

The production of chemical fertilizers has been one of the most successful industries in China in the past two decades. It has not only manifested a remarkable long-term growth rate but also avoided shortterm fluctuations. During the crisis years of the early 1960s when virtually all industries suffered set-backs, the production of fertilizers managed to progress steadily. Its success is attributed to a number of favourable factors. First of all the importance of chemical fertilizers in developing China's agriculture was fully recognized by all leaders in the Party after their early policy of reliance on the mobilization of natural fertilizers had failed. Consequently, in spite of the frequent power struggles, the chemical fertilizer industry has received uninterrupted emphasis and support. Secondly, the technological problems in producing fertilizers are less formidable than in some other industries so that in a relatively short period the Chinese have learned the basic methods of producing fertilizers and of manufacturing new equipment for this industry. Thus, production has been able to expand whether under the foreign embargo or under the self-imposed policy of self-reliance. Finally, there is no serious resource barrier in the provision of key materials for the production of fertilizers.

scholarly journals Low-frequency photospheric and wind variability in the early-B supergiant HD 2905

2018 ◽  
Vol 612 ◽  
pp. A40 ◽  
Author(s):  
S. Simón-Díaz ◽  
C. Aerts ◽  
M. A. Urbaneja ◽  
I. Camacho ◽  
V. Antoci ◽  
...  
Keyword(s):  
High Resolution ◽  
Light Curve ◽  
High Performance ◽  
Low Frequency ◽  
High Resolution Spectroscopy ◽  
Photometric Variability ◽  
Wind Variability ◽  
Short Period ◽  
Convective Motions

Context. Despite important advances in space asteroseismology during the last decade, the early phases of evolution of stars with masses above ~15 M⊙ (including the O stars and their evolved descendants, the B supergiants) have been only vaguely explored up to now. This is due to the lack of adequate observations for a proper characterization of the complex spectroscopic and photometric variability occurring in these stars. Aim. Our goal is to detect, analyze, and interpret variability in the early-B-type supergiant HD 2905 (κ Cas, B1 Ia) using long-term, ground-based, high-resolution spectroscopy. Methods. We gather a total of 1141 high-resolution spectra covering some 2900 days with three different high-performance spectrographs attached to 1–2.6m telescopes at the Canary Islands observatories. We complement these observations with the hipparcos light curve, which includes 160 data points obtained during a time span of ~1200 days. We investigate spectroscopic variability of up to 12 diagnostic lines by using the zero and first moments of the line profiles. We perform a frequency analysis of both the spectroscopic and photometric dataset using Scargle periodograms. We obtain single snapshot and time-dependent information about the stellar parameters and abundances by means of the FASTWIND stellar atmosphere code. Results. HD 2905 is a spectroscopic variable with peak-to-peak amplitudes in the zero and first moments of the photospheric lines of up to 15% and 30 km s−1, respectively. The amplitude of the line-profile variability is correlated with the line formation depth in the photosphere and wind. All investigated lines present complex temporal behavior indicative of multi-periodic variability with timescales of a few days to several weeks. No short-period (hourly) variations are detected. The Scargle periodograms of the hipparcos light curve and the first moment of purely photospheric lines reveal a low-frequency amplitude excess and a clear dominant frequency at ~0.37 d−1. In the spectroscopy, several additional frequencies are present in the range 0.1–0.4 d−1. These may be associated with heat-driven gravity modes, convectively driven gravity waves, or sub-surface convective motions. Additional frequencies are detected below 0.1 d−1. In the particular case of Hα, these are produced by rotational modulation of a non-spherically symmetric stellar wind. Conclusions. Combined long-term uninterrupted space photometry with high-precision spectroscopy is the best strategy to unravel the complex low-frequency photospheric and wind variability of B supergiants. Three-dimensional (3D) simulations of waves and of convective motions in the sub-surface layers can shed light on a unique interpretation of the variability.

scholarly journals Continuous and self-consistent CO<sub>2</sub> and climate records over the past 20 Myrs

2011 ◽  
Vol 7 (1) ◽  
pp. 437-461 ◽  
Author(s):  
R. S. W. van de Wal ◽  
B. de Boer ◽  
L. Lourens ◽  
P. Köhler ◽  
R. Bintanja
Keyword(s):  
High Resolution ◽  
Sea Level ◽  
Northern Hemisphere ◽  
Climate Models ◽  
Ice Core ◽  
Co2 Concentration ◽  
Temperature Record ◽  
Absorption Bands ◽  
The Past

Abstract. The gradual cooling of the climate during the Cenozoic has generally been attributed to a decrease in CO2 concentration in the atmosphere. The lack of transient climate models and in particular the lack of high-resolution proxy records of CO2, beyond the ice-core record prohibit however a full understanding of the inception of the Northern Hemisphere glaciation, as well as the mid-Pleistocene transition. Here we elaborate on an inverse modeling technique to reconstruct a continuous high-resolution CO2 record over the past 20 Ma, by decomposing the global deep-sea benthic δ18O record into a mutually consistent temperature and sea-level record, using a set of 1-D models of the major Northern and Southern Hemisphere ice sheets. We subsequently compared the modeled temperature record to ice core and proxy-derived CO2 data to reconstruct a continuous CO2 record over the past 20 Myrs. Results show a gradual decline from 450 ppmv around 15 Myrs ago to 280 ppmv for pre-industrial conditions, coinciding with a gradual cooling of the Northern Hemisphere land temperatures by approximately 12 K, whereas there is no long-term sea-level variation caused by ice-volume changes between 13 to 3 Myrs ago. We find no evidence for a change in climate sensitivity other than the expected decrease following from saturation of the absorption bands for CO2. The reconstructed CO2 record shows that the Northern Hemisphere glaciation starts once the average CO2 concentration drops below 265 ppmv after a period of strong decrease in CO2. Finally it might be noted that we observe only a small long-term change (23 ppmv) for CO2 during the mid-Pleistocene transition.

The past of Europe's demographic future

1999 ◽  
Vol 7 (4) ◽  
pp. 529-550 ◽  
Author(s):  
Dirk J. Van De Kaa
Keyword(s):  
Fertility Decline ◽  
Population Decline ◽  
Reproductive Potential ◽  
Reproductive Capacity ◽  
The Past ◽  
Average Family Size ◽  
Low Levels ◽  
High Level ◽  
The 19Th Century

The reproductive capacity of our species is far in excess of its needs. If all women used their reproductive potential to the full they would give birth to about 15 children on average. As averages of 6 or 7 were once sufficient to compensate for the high level of mortality, and higher numbers would have led to unacceptably high levels of population growth, that, presumably, is the level of fertility found in traditional European societies and in developing countries before the onset of fertility decline. In European societies, fertility decline began in the 19th century. It was a reaction to the disequilibrium that resulted from the long-term decline in mortality. However, a clear sequence cannot always be established. The assumption that prevailed in the 1950s and 1960s that this demographic transition, as it is customarily called, would lead to a new equilibrium appears not to have been well founded. Average family size has declined to such low levels that the age structure is seriously affected and the replacement of generations is no longer assured. A new disequilibrium has resulted. If this is a temporary phenomenon it is not an important issue. However, if it has to be assumed that future generations will also limit their reproduction to not more than 10% of their potential, the perspective is different. Even with continued high levels of immigration, population decline will then become inevitable. While some argue this will turn out to be beneficial, it is not without disadvantages.

scholarly journals Multiwavelength Monitoring of the Be/X-ray Binary XPersei - Evidence for Multiple Disk Structures

2000 ◽  
Vol 175 ◽  
pp. 589-592 ◽  
Author(s):  
P. Roche ◽  
A.E. Tarasov ◽  
V.M. Lyuty ◽  
J.S. Clark ◽  
V. Larionov
Keyword(s):  
High Resolution ◽  
Uv Spectroscopy ◽  
Optical Spectra ◽  
Monitoring Programme ◽  
Optical Photometry ◽  
X Ray ◽  
The Past ◽  
Be Star

AbstractWe present optical photometry and high resolution optical spectra of the Be star X Persei/HD 24534, the counterpart to the X-ray pulsar 4U0352+30, obtained over the past ~10 years. These spectra show a variety of behaviour, ending with the onset of a strong V/R cycle. Observations of the He 16678 line suggest several episodes of discrete disc forming. This data forms part of a major long-term multiwavelength monitoring programme (UBVRIJHKL photometry plus optical and UV spectroscopy).

A novel biofilm-membrane reactor for ammonia oxidation at low concentrations

1997 ◽  
Vol 36 (1) ◽  
pp. 51-60
Author(s):  
Yoshimasa Watanabe ◽  
Katsuki Kimura ◽  
Satoshi Okabe ◽  
Genzou Ozawa ◽  
Naoki Ohkuma
Keyword(s):  
Mass Transport ◽  
Membrane Reactor ◽  
Ammonia Oxidation ◽  
Model Simulation ◽  
Experimental Results ◽  
Rotating Biological Contactor ◽  
Biofilm Reactors ◽  
Low Concentrations ◽  
Low Levels

For the oxidation of low concentrations of NH4+-N, conventional biofilm reactors such as a rotating biological contactor encounter difficulty due to mass transport limitation of NH4+-N. Therefore, the authors have developed a novel biofilm-membrane reactor, in which biomass is fixed on the surface of rotating membrane disks to enhance NH4+-N transport into the biofilm. Three long-term bench-scale experiments were carried out and sufficient nitrification efficiency was obtained even at low levels of NH4+-N. The experimental results were evaluated in comparison with model simulation.

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