Mm In Period Research Articles

Evaluation and Modeling of Ground Water for Aqra Aquifer

From the hydrogeologist point of view, Aqra area in northern Iraq is considered as a significant area, where rainfall average in Aqra station was 654.6mm for period 2000-2016, while rainfall was 597.7mm has calculated for six stations for period 2012-2014 by Isohytal via ArcGIS in the area. The area is surrounded by the Upper Zab river from the east, and the Khazer river from the west, while Zanta river runs from its east. Due to previous and wide use of groundwater in study area, the knowledge of the response of the aquifer to different stresses is important to predict its uses in the future to optimal utilization of this aquifer. Consequently, in this study MODFLOW model under GMS platform has been used to evaluate the groundwater availability and examine response of the aquifer to stress conditions. The model has been calibrated in steady state using trial and error procedure, and verified in two states steady and unsteady, and then used for predicting purpose under two scenarios: Scenario–I running the model by pumping with recharge over 5 years the average of heads has been downed 4 meters but over 10 years has been downed 5 meters. Phase-II running the model by pumping without recharge over 5 years the average of heads has been downed 7 meters and over 10 years has been downed 8 meters. The heads have downed a little due to thickness and extend of aquifer.

Assessing the Impact of Precipitation Change on Design Annual Runoff in the Headwater Region of Yellow River, China

A significant decrease in annual runoff (AR) in the headwater region of Yellow River, China, has been observed during the past decades, which produces a recognized impact on long-term water resources management and planning. In this paper, the Pettitt method and Sequential Clustering method are used to detect the change point of AR and annual precipitation (AP) series. On the basis of the change point, the whole observed period is divided into two periods, before-point (Period I) and after-point period (Period II). The distribution characteristic of occurrence number of given extreme AP and AR and the relationship between the AP and AR in the two periods are analyzed. Then, the impact of AP change on the design AR is quantified. The results indicate that the AP and AR has a change point at the location of 1989.The distribution of occurrence number of given AP with more than 500 mm and AR with more than 150 mm in Period I is clearly different than that in Period II as well as the AP-AR relationship. The quantiles of AP and AR with the given non-exceedance probabilities of 0.8, 0.9, 0.95, 0.98, 0.99, 0.995, 0.998 and 0.999 in Period I decrease significantly compared to those in Period II. The AP decrease accounts for 53, 53, 54, 57, 60, 62, 66 and 68% of the total decrease in AR at the level of quantile with respect to the given eight non-exceedance probabilities from 0.8 to 0.999. Overall, the decrease in the AR quantile is mainly caused by the decrease in AP change.

Year-Round Irrigation Schedule for a Tomato–Maize Rotation System in Reservoir-Based Irrigation Schemes in Ghana

Improving irrigation management in semi-arid regions of Sub-Saharan Africa is crucial to respond to increasing variability in rainfall and overcome deficits in current irrigation schemes. In small-scale and medium-scale reservoir-based irrigation schemes in the Upper East region of Ghana, we explored options for improving the traditional, dry season irrigation practices and assessed the potential for supplemental irrigation in the rainy season. The AquaCrop model was used to (i) assess current water management in the typical tomato-maize rotational system; (ii) develop an improved irrigation schedule for dry season cultivation of tomato; and (iii) determine the requirement for supplemental irrigation of maize in the rainy season under different climate scenarios. The improved irrigation schedule for dry season tomato cultivation would result in a water saving of 130–1325 mm compared to traditional irrigation practices, accompanied by approximately a 4–14% increase in tomato yield. The supplemental irrigation of maize would require 107–126 mm of water in periods of low rainfall and frequent dry spells, and 88–105 mm in periods of high rainfall and rare dry spells. Therefore, year-round irrigated crop production may be feasible, using water saved during dry season tomato cultivation for supplemental irrigation of maize in the rainy season.

Microstructural Characterization and Mechanical Properties of Similar and Dissimilar Al Alloys Joined using Friction Stir Welding

The influence of pre- shot peening and welding parameters on mechanical and metallurgical properties of dissimilar and similar aluminum alloys AA2024-T3 and AA6061-T6 joints using friction stir welding have been studied. In this work, numbers of plates were equipped from sheet alloys in dimensions (150*50*6) mm then some of them were exposed to shot peening process before friction stir welding using steel ball having diameter 1.25 mm for period of 15 minutes. FSW joints were manufactured from plates at three welding speeds (28, 40, 56 mm/min) and welding speed 40mm/min was chosen at a rotating speed of 1400 rpm for welding the dissimilar pre- shot plates. Tow joints were made at rotational speed of 1000 rpm and welding speed of 40m/min from shot and without shot peening plats. Welding temperature was measured in three zones using thermocouple. Micro hardness (HV) and tensile tests were performed to evaluate the mechanical characteristic of the joints. The results show a decay in mechanical qualities when the welding speed was increased and the best result was at (28) mm/min and the opposite result was obtained when rotational speed increased and pre-shot contributed in improving of this decay at 88% of welding speed (40) mm/min and 98% at the rotational speed of 1000 rpm.
 
 

Microstructural Characterization and Mechanical Properties of Similar and Dissimilar Al Alloys Joined using Friction Stir Welding

The influence of pre- shot peening and welding parameters on mechanical and metallurgical properties of dissimilar and similar aluminum alloys AA2024-T3 and AA6061-T6 joints using friction stir welding have been studied. In this work, numbers of plates were equipped from sheet alloys in dimensions (150*50*6) mm then some of them were exposed to shot peening process before friction stir welding using steel ball having diameter 1.25 mm for period of 15 minutes. FSW joints were manufactured from plates at three welding speeds (28, 40, 56 mm/min) and welding speed 40mm/min was chosen at a rotating speed of 1400 rpm for welding the dissimilar pre- shot plates. Tow joints were made at rotational speed of 1000 rpm and welding speed of 40m/min from shot and without shot peening plats. Welding temperature was measured in three zones using thermocouple. Micro hardness (HV) and tensile tests were performed to evaluate the mechanical characteristic of the joints. The results show a decay in mechanical qualities when the welding speed was increased and the best result was at (28) mm/min and the opposite result was obtained when rotational speed increased and pre-shot contributed in improving of this decay at 88% of welding speed (40) mm/min and 98% at the rotational speed of 1000 rpm.
 
 

Microstructural Characterization and Mechanical Properties of Similar and Dissimilar Al Alloys Joined using Friction Stir Welding

ان تاثير القذف بالكرات الفولاذية السابق لعملية اللحام وكذلك سرعته الخطية والدورانية على الخواص الميكانيكية والمتالورجية لوصلات لحام انتجت بطريقة الخلط الاحتكاكي لسبائك الالمنيوم المتشابهة وغير المتشابهة وذات المتانة العالية - AA2024 T3–AA6061 .تم تحضير عددا من الصفائح من السبائك المختارة بابعاد ملم وان عدد من هذه السبائك تعرضت الى القذف بكرات فولاذية قطرها (1.25) ملم ولمدة (15) دقيقة بعدها عدة وصلات لحام انجزت من الصفائح غير المتماثلة والمتماثلة المقذوفة وغير المقذوفة وبسرعة لحام (28,40,56)mm/min مع تثبيت السرعة الدورانية عند (1400)Rpm وقد انتخبت سرعة لحام (40)mm/min وبالسرعة الدورانية نفسها (1400)Rpm في عملية لحام صفائح اللحام التي تم قذفها لبيان تاثير عملية القذف على اما الخواص الميكانيكية فقد تمت عملية اللحام بواسطة ماكنة تفريز عمودية وتم قياس التغير في درجة الحرارة في مناطق اللحام باستخدام مزدوج حراري وكذلك اجري اختبار الصلادة المايكروية والشد ومن النتائج التي تم الحصول عليها وجد انخفاض في الخواص الميكانيكة عند زيادة في السرعة وان افضل نتيجة ظهرت عند سرعة خطية مقدارها (28m/min) وان عملية القذف بالكرات الفولاذية قبل عملية اللحام ساهمت في تحسين الخواص الميكانيكية لدرجة مقاربة لنتائج المعدن الاساس وقد وجد تحسن في الخواص الميكانيكة عند زيادة السرعة الدورانية.

The role of serial measurements of cervical length in asymptomatic women with triplet pregnancy

Objective: To assess the predictive accuracy of serial measurements of cervical length (CL) for preterm birth in asymptomatic women with triplet pregnancy.Methods: A retrospective study of women with triplets who underwent serial sonographic measurements of CL until 28–32 weeks of gestation. The predictive accuracy of CL for preterm birth was determined at 4 periods along gestation: 18–20 weeks (period 1), 21–24 weeks (period 2), 25–27 weeks (period 3) and 28–32 weeks (period 4).Results: A total of 431 measurements of CL from were analyzed. CL decreased in a linear manner across gestation: 40.8 ± 7.1 mm, 36.5 ± 8.4 mm, 29.9 ± 11.4 mm and 25.0 ± 11.8 mm in periods 1, 2, 3 and 4, respectively. The difference in CL between women who did and did not deliver prematurely was small before 25 weeks (periods 1&2) but became more pronounced later in pregnancy (periods 3&4), mainly due to a rapid cervical shortening between periods 2 and 3 (shortening rate −29.0 ± 20.0% vs. −12.6 ± 20.5%, respectively, p = .01). The best predictors of preterm birth were either a single measurement of CL during period 3 or the degree of cervical shortening between periods 2 and 3.Conclusions: Care providers should be aware of the limited predictive value of cervical length before 25 + 0 weeks in triplet pregnancies.

Influence of climate variability and human activities on stream flow variation in the past 50 years in Taoer River, Northeast China

Taoer River Basin, which is located in the west of Northeast China, is an agropastoral ecotone. In recent years, the hydrological cycle and water resources have changed significantly with the deterioration of the environment. Many water problems such as river blanking, wetland shrinking and salinization have occurred in this region. All of these phenomena were directly caused by changes in stream flow under climate variability and human activities. In light of the situation, the impact of climate variability and human activities on stream flow should be identified immediately to identify the primary driving factors of basin hydrological processes. To achieve this, statistical tests were applied to identify trends in variation and catastrophe points in mean annual stream flow from 1961 to 2011. A runoff sensitive coefficients method and a SIMHYD model were applied to assess the impacts of stream flow variation. The following conclusions were found: 1) The years 1985 and 2000 were confirmed to be catastrophe points in the stream flow series. Thus, the study period could be divided into three periods, from 1961 to 1985 (Period I), 1986 to 2000 (Period II) and 2001 to 2011 (Period III). 2) Mean annual observed stream flow was 31.54 mm in Period I, then increased to 65.60 mm in Period II and decreased to 2.92 mm in Period III. 3) Using runoff sensitive coefficients, the contribution of climate variability was 41.93% and 43.14% of the increase in stream flow during Periods II and III, suggesting that the contribution of human activities to the increase was 58.07% and 56.86%, respectively. 4) Climate variability accounted for 42.57% and 44.30% of the decrease in stream flow, while human activities accounted for 57.43% and 55.70% of the decrease, according to the SIMHYD model. 5) In comparison of these two methods, the primary driving factors of stream flow variation could be considered to be human activities, which contributed about 15% more than climate variability. It is hoped that these conclusions will benefit future regional planning and sustainable development.

Test Results of the CLIC Damping Wiggler Prototype

The Compact Linear Collider (CLIC) will require ultralow emittance electron and positron beams. Such emittance will be achieved by radiative damping in the CLIC damping rings that will be realized by a use of high-field short-period superconducting damping wigglers. In the course of the CLIC technical feasibility studies, a full-scale damping wiggler prototype was fabricated in BINP. Main parameters of the wiggler are 51 mm of period, 3 T of magnetic field, 1.8 m of magnetic length, 18 mm of the pole gap, and indirect cooling by LHe. Four cryocoolers were used in the wiggler design, which allow its ordinary operation without LHe consumption. Above the magnetic requirements, the main design challenges for this prototype are scalability, particularly of the cooling concept, modularity, and the capability of sustaining a high radiative heat load. The wiggler powering tests and performance of the cryogenic system are described in this paper.

Characteristics and importance of rill and gully erosion: a case study in a small catchment of a marginal olive grove

Measurements of gullies and rills were carried out in an olive orchard microcatchment of 6.1 ha over a 4-year period (2010-2013). No tillage management allowing the development of a spontaneous grass cover was implemented in the study period. Rainfall, runoff and sediment load were measured at the catchment outlet. The objectives of this study were: 1) to quantify erosion by concentrated flow in the catchment by analysis of the geometric and geomorphologic changes of the gullies and rills between July 2010 and July 2013; 2) to evaluate the relative percentage of erosion derived from concentrated runoff to total sediment yield; 3) to explain the dynamics of gully and rill formation based on the hydrological patterns observed during the study period; and 4) to improve the management strategies in the olive grove. Control sections in gullies were established in order to get periodic measurements of width, depth and shape in each campaign. This allowed volume changes in the concentrated flow network to be evaluated over 3 periods (period 1 = 2010-2011; period 2 = 2011-2012; and period 3 = 2012-2013). The cumulative precipitation values were 610 mm, 219 mm and 406 mm for period 1, 2 and 3, respectively, whereas the sediment ratios of rill erosion to total sediment yield were 44% and 118%, respectively, with a negative value (as a result of the volume reduction of rills and gullies) in period 3 when the total load was equal to 0.4 t ha-1. The increased development of the gully network was associated to intense events with a return period of the maximum intensity in 30 minutes greater than 2 years. A high dependency on the sequence of events according to their intensity values could explain the sedimentary budget in the catchment. Most of the events generating runoff in the catchment could contribute to interrill and rill erosion, but only very intense events would allow the runoff to transport sediment to the outlet. In addition to the grass cover, control measures in the gullies would substantially improve the sustainability of the farm. These gullies are important sediment sources, particularly in autumn when there is no vegetation cover and intense rainfall events occur.

Dosimetric Impact of Intrafraction Motion During RapidArc Stereotactic Vertebral Radiation Therapy Using Flattened and Flattening Filter-Free Beams

To study the dosimetric impact of relatively short-duration intrafraction shifts during a single fraction of RapidArc delivery for vertebral stereotactic body radiation therapy (SBRT) using flattened (FF) and flattening filter-free (FFF) beams. The RapidArc plans, each with 2 to 3 arcs, were generated for 9 patients using 6-MV FF and 10-MV FFF beams with maximum dose rates of 1000 and 2400 MU/min, respectively. A total of 1272 plans were created to estimate the dosimetric consequences in target and spinal cord volumes caused by intrafraction shifts during one of the arcs. Shifts of 1, 2, and 3 mm for periods of 5, 10, and 30 seconds, and 5 mm for 5 and 10 seconds, were modelled during a part of the arc associated with high doses and steep dose gradients. For FFF plans, shifts of 2 mm over 10 seconds and 30 seconds could increase spinal cord Dmax by up to 6.5% and 13%, respectively. Dosimetric deviations in FFF plans were approximately 2-fold greater than in FF plans. Reduction in target coverage was <1% for 83% and 96% of the FFF and FF plans, respectively. Even short-duration intrafraction shifts can cause significant dosimetric deviations during vertebral SBRT delivery, especially when using very high dose rate FFF beams and when the shift occurs in that part of the arc delivering high doses and steep gradients. The impact is greatest on the spinal cord and its planning-at-risk volume. Accurate and stable patient positioning is therefore required for vertebral SBRT.

Glyoxal crosslinking of cell-seeded chitosan/collagen hydrogels for bone regeneration

Chitosan and collagen are natural biomaterials that have been used extensively in tissue engineering, both separately and as composite materials. Most methods to fabricate chitosan/collagen composites use freeze drying and chemical crosslinking to create stable porous scaffolds, which subsequently can be seeded with cells. In this study, we directly embedded human bone marrow stem cells (hBMSC) in chitosan/collagen materials by initiating gelation using β-glycerophosphate at physiological temperature and pH. We further examined the use of glyoxal, a dialdehyde with relatively low toxicity, to crosslink these materials and characterized the resulting changes in matrix and cell properties. The cytocompatibility of glyoxal and the crosslinked gels were investigated in terms of hBMSC metabolic activity, viability, proliferation and osteogenic differentiation. These studies revealed that glyoxal was cytocompatible at concentrations below about 1 mM for periods of exposure up to 15 h, though the degree of cell spreading and proliferation were dependent on matrix composition. Glyoxal-crosslinked matrices were stiffer and compacted less than uncrosslinked controls. It was further demonstrated that hBMSC can attach and proliferate in three-dimensional matrices composed of 50/50 chitosan/collagen, and that these materials supported osteogenic differentiation in response to stimulation. Such glyoxal-crosslinked chitosan/collagen composite materials may find utility as cell delivery vehicles for enhancing the repair of bone defects.

Long Rotating Coil System Based on Stretched Tungsten Wires for Insertion Device Characterization

A very precise rotating coil was developed using stretched tungsten wires in a new geometric arrangement for the accurate magnetic characterization of insertion devices (IDs). Many sources of errors were analyzed, and a procedure to evaluate coil defects by means of a dipolar magnetic field is presented. Tests were performed in a 2-T planar wiggler, which is 2.8 m long, with 180 mm of period, of the Brazilian synchrotron light source (LNLS). The advantages of using the tungsten wires and the measurement repeatability and accuracy are also discussed.

How sweet it is: sensing low glucose in the carotid body

How sweet it is: sensing low glucose in the carotid body

ATTENUATION WITH SOIL DEPTH OF DYNAMIC FLUCTUATIONS IN THE RATIO OF CHEMICALS TO IRRIGATION WATER IN CHEMIGATION

Use of chemigation for the application of fertilizers and chemicals through the irrigation system has increasedworldwide. The concentration is usually controlled and maintained constant over the irrigation duration. Dynamicfluctuation in the concentration may, however, result in inaccurate application of the fertilizers and chemicals. This may, inturn, cause a reduction in crop yield when the application amounts are lower than the planned amounts, or present anenvironmental hazard when they are higher. These dynamic fluctuations in the chemical concentration of the irrigation waterdecay with soil depth due to the convection-dispersion nature of the transport process of infiltrating water during irrigation.An analytical solution, which employs the Fourier Transform method, is used here to estimate the decay of these dynamicfluctuations as water infiltrates from the soil surface to the root zone. This solution assumed constant irrigation flux and soilmoisture conditions, typical to high frequency irrigation. It assumes periodic fluctuations in the chemical concentration ofthe irrigation water. A general analytical solution was derived for these asymmetric dynamic periodic fluctuations. The effectsof fluctuation period, asymmetric time factor, and high and low concentration values within the irrigation period on the decayprocess were evaluated and results are presented for clay loam and sandy loam soils. Damping depth was chosen tocharacterize this decay process. It is the depth at which the amplitude of the chemical concentration decays by a factor exp(-1). 37% of its value at the soil surface Two (high and low) damping depths characterize the decay process of asymmetric timefluctuations. Damping depths for symmetric fluidations in clay loam were 21, 58, 138 mm for periods of 2, 10, 30 days, and78, 239, 682 mm in sandy loam for the same periods, showing the significance of soil texture and fluctuation periods. Theeffect of asymmetry was assessed for constant average concentration. High damping depths values of 92, 156, 235, and308 mm were computed for asymmetric factors 0.1, 0.25, 0.50, and 0.80, while the low damping depths were 322, 296, 239,and 145 mm, respectively, in sandy loam and 10 days period, showing a significant effect of asymmetry. This analysis is usefulfor assessing the level of accuracy required for controlling chemical concentration during chemigation, considering the soilbuffer effect.

In vitro DNA damage and mutations induced by a macrocyclic tetraamide chromium(V) complex: implications for the role of Cr(V) peptide complexes in chromium-induced cancers.

Electron paramagnetic resonance and electronic absorption spectroscopies have shown that unlike the bidentate Cr(V) complex [Cr(ehba)2O]- (ehba = 2-hydroxy-2-ethylbutanoato(2-)), I, the macrocyclic tetradentate complex, [Cr (mampa-dcb)(O)]- (mampa-dcb = 5,6-(4,5-dichlorobenzo)-3,8,11,13-tetraoxo-2,2,9,9-tetrameth yl-12,12-diethyl-1, 4,7,10-tetraazacyclotridecane), II, is substitutionally inert. Low levels of DNA strand cleavage were observed after treatment with II under physiological conditions (50 mM sodium phosphate, pH 7.4, 37 degrees C) at concentrations as high as 2 mM for periods as long as 2 days. II also induces a lower number of revertants in mutation assays with Salmonella typhimurium TA100 than I when identical Cr concentrations are applied. The slopes of the linear portion of the dose-response curves are parallel, however, indicating that the mutagenicity of II is comparable to I. II is stable toward ligand exchange, reduction and disproportionation in the mutagenicity test medium and also in the presence of bacteria and the common cell reductant, glutathione. This indicates that ligand exchange with DNA and/or reduction to Cr(IV) are not responsible for the mutagenicity of II (unlike I). It is believed that II reversibly but weakly intercalates with DNA placing the Cr(V) center in close proximity for hydrogen atom abstraction or oxo-transfer reactions to ensure. This tetraamide complex is a good structural and biomimetic model for non-sulfur-containing Cr(V) peptide species that may form in vivo from reactions of Cr(VI) with peptides. Hence, it is likely to be relevant to understanding one possible mechanism by which Cr(VI) causes cancer.

A Comparative Study of the Radioprotective Effects of Cysteamine, WR-2721, and WR-1065 in Cultured Human Cells

The compounds, 2-mercaptoethylamine (cysteamine), S-2-(3-aminopropylamino)ethylphosphorothioic acid (WR-2721), and N-(2-mercaptoethyl)-1,3-diaminopropane (WR-1065) were tested for toxicity and radioprotective effect in cultured human cells using viability (reproductive death) as an indicator. WR-2721 and WR-1065 had no harmful effect at concentrations of 4 and 10 mM for periods up to 3 hr whereas cysteamine was toxic if left in contact with the cells for more than 30 min. The response of the cells to radiation was measured after a 30-min treatment with 4 mM of each protective agent. Survival curves were constructed and the following dose reduction factors (DRFs) were calculated: WR-2721, 1.3; cysteamine, 2.3; WR-1065, 2.9. Increasing the concentration of protective agent did not increase the DRF under these conditions except in the case of cysteamine. Extending the period of treatment with drug before irradiation increased the DRF for WR-2721 and WR-1065; values up to 1.8 and 3.4 were obtained with 10 mM WR-2721 and WR-1065, respectively. With these two compounds, the rate of development of protection with time is almost independent of concentration until the maximum is attained; it is probably controlled by the rate of transport across the cell membrane, in the case of WR-1065, and by

A study of the electroplastic effect in metals

Abstract : The effects of high density, direct current pulses (100 to 1000 A/sq. mm for periods of 55-120 microsecs) on the flow stress determined in an Instron tensile testing machine were studied in a number of polycrystalline metals representing various crystal structures (Pb, Sn, Fe and Ti), with most attention being focused on Ti. The current pulses produced a decrease in the flow stress delta (o sub p) in all four metals. The work on Ti indicated that delta (o sub p) contains a contribution in addition to heating and pinch effects. This contribution (the electroplastic effect) increased significantly with current density, interstitial content and temperature (77-300K), to a lesser degree with strain, but no change was detected for a 25 fold increase in strain rate. Computer calculations of the dynamic stress changes associated with the approximately sinusoidal current-time pulses employed here yielded a contribution due to the electron-dislocation interaction (for a current density of 5000 A/sq mm at 300K) which was 32% of delta (o sub p). A model is proposed for the electroplastic effect which is based on theoretical considerations that the current flow exerts a force on the dislocations which adds to the applied force pushing a dislocation against obstacles. Complementary studies were performed on: (a) the decremental unloading method for determining the internal stress in metals, (b) the effects of temperature, gain size and interstitial content on the flow stress of Ti and (c) plastic instability in Ti sheet. (Author)

Effects of load and duration of tension on pain induced by muscular contraction.

Pain was induced in the ischemic forearm in more than 300 tests in seven subjects by an exercise which consisted of compression of an air bulb to raise or maintain a mercury column at 50, 100, or 200 mm for periods of 1, 2, 4, or 5.5 sec. The rate of pain development could be correlated with the product ( P) of the number of contractions, square root of the load (in mm Hg), and cube root of the duration of contraction (in sec). Slight pain appeared at a product of about 345 P, moderate pain at approximately 433 P, severe pain at 536 P, and intolerable pain at 626 P. A similar relationship could be shown in maintained contraction provided the total duration was treated as if each 5.5 sec of the maintained contraction constituted a separate contraction. Ischemia of the arm for periods up to 15 min had no effect on product. Recovery from the effect of exercise was complete in 10 min. Simultaneous exercise of the other arm had no effect on the rate of pain development. The results support the concept that muscle pain results from the local accumulation of a slowly diffusible material released during muscle contraction.