Assessing salinity leaching efficiency in three soils by the HYDRUS-1D and -2D simulations

Salinity leaching is necessary to sustain agricultural production in irrigated croplands. Improving salinity leaching efficiency not only conserves water but also reduces groundwater contamination. Current leaching requirement (LR) calculations are based on steady-state and one-dimensional (1D) approaches, and consequently, this LR concept may not be applicable to drip irrigation (approximately 2D), which is becoming more common due to its higher water use efficiency. The aims of this study were to assess the salinity leaching fraction (LF) in clay, loam, and sand soils under 1D (to mimic sprinkler irrigation) and 2D (to mimic drip irrigation) transient conditions with a numerical model (HYDRUS). Water applications used the actual irrigation scheme in an almond orchard located in central California without considering precipitation. Model simulations showed that soil salinity at the lower boundary (depth of 150 cm) reached steady-state in 10 years in HYDRUS-1D simulations. The leaching fractions calculated from the ratio of drainage-water depth to irrigation-water depth (LFw = Ddw/Diw) and irrigation-water salinity to drainage-water salinity (LFEC = ECiw/ECdw) from HYDRUS-1D were similar among different textured soils. However, they were much higher under drip irrigation (2D) than under sprinkler irrigation (1D) when the same amount of water was applied, and LFEC values were much greater than the LFw values under 2D simulations. Salt balance (SB) and leaching efficiency (LE) indicated that sprinkler irrigation (1D) is more effective for salinity leaching than drip irrigation (2D). To improve salinity leaching efficiency, further evaluation of LRs under drip irrigation is needed

Towards an analytical framework of science communication models

This chapter reviews the discussion in science communication circles of models for public communication of science and technology (PCST). It questions the claim that there has been a large-scale shift from a ‘deficit model’ of communication to a ‘dialogue model’, and it demonstrates the survival of the deficit model along with the ambiguities of that model. Similar discussions in related fields of communication, including the critique of dialogue, are briefly sketched. Outlining the complex circumstances governing approaches to PCST, the author argues that communications models often perceived to be opposed can, in fact, coexist when the choices are made explicit. To aid this process, the author proposes an analytical framework of communication models based on deficit, dialogue and participation, including variations on each

Towards a knowledge-rich learning environment in preparatory secondary education

In this case study a novel educational programme for students in preparatory vocational education was studied. The research questions were: (1) Which teaching/learning processes occur in a simulated workplace using the concept of a knowledge-rich workplace? (2) What is the role of models and modelling in the teaching/learning processes? The curriculum project consisted of design and construction tasks. The students were collaboratively involved in the process of designing a tricycle for a real customer. This real-life activity creates opportunities for students to develop and use models, which can be used in more than in one context. The case study explored how the teachers deal with the students' explicit and implicit need for knowledge and skills. The main findings are that teachers more often provide this knowledge, rather than guide the students in reconstructing it, and towards the end of the project, knowledge tended to remain situated

Method for passivating at least a part of a substrate surface

A method for passivating at least a part of a surface of a semiconductor substrate, wherein at least one layer comprising at least one a-Si:H passivation layer is realized on said part of the substrate surface by: - generating a plasma (P) by means of at least one plasma source (3) mounted on the process chamber (5) at a distance (L) from the substrate surface, at least part of the plasma (P) being injected into the chamber (5) and achieving a supersonic speed; - contacting at least a part of the plasma (P), injected into the chamber (5), with the said part of the substrate surface; and - supplying at least one precursor suitable for passivation layer realization to the said part of the plasma (P) via a plurality of injection nozzles (19) of an injector device (17), such that the density of the precursor at each injection nozzle (19) is lower than 12x1022 particles/m3

Method for passivating at least a part of a substrate surface

A method for passivating at least a part of a surface of a semiconductor substrate, wherein at least one layer comprising at least one a-Si:H passivation layer is realized on said part of the substrate surface by: - generating a plasma (P) by means of at least one plasma source (3) mounted on the process chamber (5) at a distance (L) from the substrate surface, at least part of the plasma (P) being injected into the chamber (5) and achieving a supersonic speed; - contacting at least a part of the plasma (P), injected into the chamber (5), with the said part of the substrate surface; and - supplying at least one precursor suitable for passivation layer realization to the said part of the plasma (P) via a plurality of injection nozzles (19) of an injector device (17), such that the density of the precursor at each injection nozzle (19) is lower than 12x1022 particles/m3

Psychosocial issues of women with type 1 diabetes transitioning to motherhood: a structured literature review

BACKGROUND: Life transitions often involve complex decisions, challenges and changes that affect diabetes management. Transition to motherhood is a major life event accompanied by increased risk that the pregnancy will lead to or accelerate existing diabetes-related complications, as well as risk of adverse pregnancy outcomes, all of which inevitably increase anxiety. The frequency of hyperglycaemia and hypoglycaemia often increases during pregnancy, which causes concern for the health and physical well-being of the mother and unborn child. This review aimed to examine the experiences of women with T1DM focusing on the pregnancy and postnatal phases of their transition to motherhood. METHODS: The structured literature review comprised a comprehensive search strategy identifying primary studies published in English between 1990-2012. Standard literature databases were searched along with the contents of diabetes-specific journals. Reference lists of included studies were checked. Search terms included: 'diabetes', 'type 1', 'pregnancy', 'motherhood', 'transition', 'social support', 'quality of life' and 'psychological well-being'. RESULT: Of 112 abstracts returned, 62 articles were reviewed in full-text, and 16 met the inclusion criteria. There was a high level of diversity among these studies but three common key themes were identified. They related to physical (maternal and fetal) well-being, psychological well-being and social environment. The results were synthesized narratively. CONCLUSION: Women with type 1 diabetes experience a variety of psychosocial issues in their transition to motherhood: increased levels of anxiety, diabetes-related distress, guilt, a sense of disconnectedness from health professionals, and a focus on medicalisation of pregnancy rather than the positive transition to motherhood. A trusting relationship with health professionals, sharing experiences with other women with diabetes, active social support, shared decision and responsibilities for diabetes management assisted the women to make a positive transition. Health professionals can promote a positive transition to motherhood by proactively supporting women with T1DM in informed decision-making, by facilitating communication within the healthcare team and co-ordinating care for women with type 1 diabetes transitioning to motherhood

Accurate control of ion bombardment in remote plasmas using pulse-shaped biasing

This paper deals with a pulsed biasing technique employed to a downstream expanding thermal plasma. Two pulsed biasing approaches are presented: asymmetric rectangular pulses and modulated pulses with a linear voltage slope during the pulse, and their applicability is discussed on the basis of the intrinsic capacitance of the processed substrate-layer system. The substrate voltage and current waveforms are measured, and the relation to the obtained ion energy distributions is discussed. Accurate control of the ion bombardment is demonstrated for both aforementioned cases, and the cause of broadening of the peaks in the ion energy spectra is determined as well. Moreover, several methods to determine the modulated pulse duration, such that the sloping voltage exactly compensates for the drop of the substrate sheath potential due to charging, are presented and their accuracy is discussed. © 2009 American Institute of Physics. U7 - Export Date: 24 March 2010 U7 - Source: Scopus U7 - Art. No.: 07330

Large-Scale Utilization of Saline Groundwater for Irrigation of Pistachios Interplanted with Cotton

Twelve, 19.5 acre test plots arranged in a randomized complete block design are set within two 155 acre fields to provide a realistic production environment. These blocks of welldrained Panoche clay loam were formerly irrigated with California Aqueduct water and sprinklers for the last 30 years. Overall the field electrical conductivity (EC) ranged from 0.5 to 4.5, averaging 1.57 dS/m to a 3-foot depth. Saturation extract boron was 0.6 ppm. The area is underlain by a semi-saline aquifer that has been made worse over the decades by contamination from oilfield leachate water. Several production wells were drilled in fall 2003 to begin using this water. A drip tape irrigation system was set up to allow the planting of 6 rows of cotton every 22 feet the first year of the project (2004) followed with the planting of 1 year old pistachio seedling rootstocks March 2005 in 22 foot rows interplanted with 4, 38 inch rows of pima cotton. Salinity of the shallow groundwater for the test fields has varied from 4 to 7.5 dS/m with 8 to 11 ppm B. Three treatments were imposed: AQUEDUCT/CONTROL: EC ~ 0.4 dS/m (Aqueduct water only), BLEND: EC ~ 2.5 dS/m (50/50 mix) and WELL: EC ~ 5 dS/m.Chloride and boron contents in late season cotton petioles and pistachio leaf tissues were significantly higher in the WELL treatment compared to the Control. Saturation extract EC and B in the top three feet of rootzone were significantly increased in the BLEND and WELL treatments over the Control at the end of the season, with most salts increasing significantly to 3 feet with a significant increase in Cl to 5 feet.Cotton yield and tree development: Pima cotton lint yields were nearly 4 bale/acre in 2004, but crashed to about 2 bale/acre in 2005 due to very cool spring conditions that made for poor stand establishment. Cotton yields and plant height were unaffected by salinity. Spring 2006 provided excellent conditions for cotton growth, but excessive salts accumulated in the top 4 inches of the Well treatment beds reduced cotton emergence by 14% (statistically insignificant) and lint yield from the saline Well treatment was reduced by 275 lb/ac compared to the Aqueduct water. However, the Well treatment yield was still excellent at 3.12 bale/ac.Increase in pistachio rootstock diameter and general tree development was unaffected by salinity for both rootstocks for the first three years, but PG1 rootstocks showed a significant 7% decrease at the end of 4th leaf (Figure 1). However, Photoshop® pixel counts of green foliage down the row show an equal amount of green foliage for all treatments as of 10/18/08.Salinity and sustainability: At the end of 2006, after three seasons of cotton irrigation this program applied about 6,600, 32,500 and 54,000 lb/ac of salt in the Aqueduct, Blend and Well treatments, respectively. Rootzone salinity to 5 feet in the wettest part of the profile (between the two hoses) measured by Spring and Fall soil samples has remained surprisingly stable at about an ECe of 2.5 dS/m for the Aqueduct and about 5 to 6 dS/m for the Well treatment. However, in-season ECe in the top two feet is much higher as water and salts sub up from the buried drip tape. Without 6 to 10 inches of effective rainfall or fresh water winter irrigation for efficient leaching this system may not be sustainable. Due to the decrease in cotton yield in 2006, combined with a 50% increase in the Well water EC over the last four years we reduced the salinity of the Well treatment (by blending with Aqueduct water) down to 4.5 dS/m. This is about the salinity of the Well at the start of the test in 2004. After one year of cotton and four years of drip tape irrigation in the pistachios a total of 73,823 lb salt/wetted acre (about a 9.5 foot wide zone of subbing) was applied in the active rootzone of the Well treatment compared to 8,050 lb salt/wetted acre for Aqueduct water.At an average pima price of $1.08/lb, an economic analysis of cotton production and yields for the year prior to and first two years after planting pistachios shows a net return of$2,120 for Aqueduct water @ $120/ac-ft and$2,249 for Well water @ $45/ac-ft for this system

Passive and active spectroscopy on flowing plasmas

The equil. departures of two types of flowing plasmas were studied exptl. The combination of abs. emission spectroscopy with the non-intrusive active tool of Thomson/Rayleigh scattering made it possible to compare the at. state distribution function (ASDF) with its equil. form. The electron excitation kinetics (EEK) of a highly recombinative Cascaded Arc Created Magnetized Expanding Plasma was studied using time resolved laser induced fluorescence. The recombination process was found to be largely affected by heavy particle excitation kinetics (HEK). A comparable study of an inductively coupled plasma revealed that the deviations from partial local Saha equil. (pLSE) were much less pronounced. To get insight in this plasma, global active spectroscopy was performed by following the response to the power interruption

Silicon surface passivation by hot-wire CVD Si thin films studied in situ surface spectroscopy

Silicon thin films can provide an excellent surface passivation of crystalline silicon (c-Si) which is of importance for high efficiency heterojunction solar cells or diffused emitter solar cells with well-passivated rear surfaces. Hot-wire chemical vapor deposition (hotwire CVD) is an attractive method to synthesize Si thin films for these applications as the method is ion-bombardment free yielding good quality films over a wide range of deposition rates. The properties of the interface between Si thin films and H-terminated c-Si substrates have been studied during film growth by three complementary in situ techniques. Spectroscopic ellipsometry has been used to determine the optical properties, film thickness and surface roughness whereas information on the H-bonding modes and H-depth profile has been obtained by attenuated total reflection infrared spectroscopy. Second-harmonic generation (SHG), a nonlinear optical technique sensitive to surface and interface states, has been used to probe two-photon resonances related to modified Si-Si bonds at the interface. The observations have been correlated with ex situ lifetime spectroscopy experiments. On the basis of the results, the growth and surface passivation mechanism of the films will be discussed, including the role of defect states, built-in electric fields, (nanometer-level) epitaxial growth, influence of the substrate temperature, etc