Water losses, distribution, and use under a center-pivot irrigation system

Non-Peer ReviewedA study was conducted to quantify the water losses that occur under center pivot irrigation. Spray and drift losses were calculated as the difference between the amount of water applied, as measured by a flow meter attached to the mainline pipe, and the amount of water collected by a network of rain gauges located just above the crop canopy. Evapotranspiration from durum was measured directly using an energy balance/Bowen ratio system. Spray and drift losses at times exceeded 49 % of the water applied. The mean loss over the 1988 growing season was 29 %. The extent of the loss was highly dependent on the wind speed, wind direction relative to the sprinkler lateral and the vapour pressure deficit. Distribution of water across the field was extremely variable and again highly dependent on wind speed and direction. At times 93 % of applied water was lost within 24 hours of application with daily evapotranspiration exceeding 14 mm. Evaporation rates were often significantly increased by advective energy so that latent energy flux densities exceeded net radiation by up to 30 %. In most cases evaporation became soil limited within three days of irrigation, despite the fact that for most of the growing season soil water content in the 50-180 cm soil layer was seldom less than field capacity. Neutron probe data indicated that there was little uptake of water in this layer

Growth and water use of irrigated and dryland lentils and wheat

Non-Peer ReviewedLentils are becoming an increasingly more important crop in Saskatchewan with over 230,000 ha planted in 1987. A large part of this acreage was in the Brown Soil Zone. To date lentil water relations and adaptation to water deficits are largely undescribed. This study was initiated to determine the drought tolerance characteristics of lentils and to compare them to those of wheat growing under the same weather conditions. Dryland lentils exhibited considerable drought tolerance with large changes in osmotic potential in response to increasing soil water deficits. Despite maintaining high levels of turgor, values of stomatal conductance were very low. This behaviour enabled leaves to maintain high relative water contents and survive an extensive dry period. In contrast wheat displayed little drought tolerance. Consequently throughout the growing season the rates of dry land to irrigated above-ground dry matter was consistently higher for lentils than for wheat and at final harvest was 0. 71 and 0.41 for the two crops, respectively. Wheat and lentils had similar water use efficiencies, but lentils used more water because of their greater dry matter production. Very high dry matter production in irrigated lentils did not translocate into high grain yields

A new distance learning national framework for social work continuing education: critical reflections on the first phases of implementation

This article utilizes a range of secondary research methodologies to explore the challenges and opportunities that have arisen from the establishment and first years of delivery of a new single and predominantly distant learning national post-qualifying framework. The continuing professional education and learning (CPEL) framework is directly commissioned by the professional regulator Social Care Wales, provided by an alliance of four universities (Bangor, Cardiff, Glyndwr and Swansea) and actively involves employers, practitioners and service users in their development. Critical reflections on the early implementation of the Experienced, Senior and Consultant Programs that contribute to the CPEL framework will help understand the key characteristics, challenges and opportunities post-qualifying education for social workers can bring. The article commences with an analysis of the moves to design a national post-qualification framework that is more accessible, flexible and responsive than the previous patchwork quilt set-up, including an examination of the increased role of distance learning and the teaching methodologies that support it. It then critically summarizes the specific context and developments of the CPEL framework. This is followed by substantive analyses of the key messages. These messages are of the value of; provider collaboration, quality of e-learning experience, employer commitment and student-perceived competence/satisfaction

Mid-Infrared Imaging of the Bipolar Planetary Nebula M2-9 from SOFIA

We have imaged the bipolar planetary nebula M2-9 using SOFIA's FORCAST instrument in six wavelength bands between 6.6 and 37.1 $\mu m$. A bright central point source, unresolved with SOFIA's $\sim$ 4${''}$-to-5${''}$ beam, is seen at each wavelength, and the extended bipolar lobes are clearly seen at 19.7 $\mu m$ and beyond. The photometry between 10 and 25 $\mu m$ is well fit by the emission predicted from a stratified disk seen at large inclination, as has been proposed for this source by Lykou et al and by Smith and Gehrz. The principal new results in this paper relate to the distribution and properties of the dust that emits the infrared radiation. In particular, a considerable fraction of this material is spread uniformly through the lobes, although the dust density does increase at the sharp outer edge seen in higher resolution optical images of M2-9. The dust grain population in the lobes shows that small ($$ 1 $\mu m$) particles appear to be present in roughly equal amounts by mass. We suggest that collisional processing within the bipolar outflow plays an important role in establishing the particle size distribution.Comment: 40 pages, 9 figures, 2 table

Relationship between vertical and horizontal magnetic fields in the quiet Sun

Vertical magnetic fields have been known to exist in the internetwork region for decades, while the properties of horizontal magnetic fields have recently been extensively investigated with \textit{Hinode}. Vertical and horizontal magnetic fields in the internetwork region are considered to be separate entities and have thus far not been investigated in a unified way. We discover clear positional association between the vertical and horizontal magnetic fields in the internetwork region with \textit{Hinode}. Essentially all of the horizontal magnetic patches are associated with the vertical magnetic patches. Alternatively, half of the vertical magnetic patches accommodate the horizontal magnetic patches. These horizontal patches are located around the borders of the vertical patches. The intrinsic magnetic field strength as obtained with the Stokes $V$ line ratio inside the horizontal patches is weak, and is in sub-equipartition field regime ($B<700$ G), while the field strength outside the horizontal patches ranges from weak to strong (kG) fields. Vertical magnetic patches are known to be concentrated on mesogranular and supergranular boundaries, while the horizontal magnetic patches are found only on the mesogranular boundaries. These observations provide us with new information on the origin of the vertical and horizontal internetwork magnetic fields, in a unified way. We conjecture that internetwork magnetic fields are provided by emergence of small-scale flux tubes with bipolar footpoints, and the vertical magnetic fields of the footpoints are intensified to kG fields due to convective collapse. Resultant strong vertical fields are advected by the supergranular flow, and eventually form the network fields.Comment: 50 pages, 11 figures, accepted for publication in The Astrophysical Journa

Explanation of the activity sensitivity of Mn I 5394.7 \AA

There is a long-standing controversy concerning the reason why the Mn I 5394.7 A line in the solar irradiance spectrum brightens more at larger activity than most other photospheric lines. The claim that this activity sensitivity is caused by spectral interlocking to chromospheric emission in Mg II h & k is disputed. Classical one-dimensional modeling is used for demonstration; modern three-dimensional MHD simulation for verification and analysis. The Mn I 5394.7 A line thanks its unusual sensitivity to solar activity to its hyperfine structure. This overrides the thermal and granular Doppler smearing through which the other, narrower, photospheric lines lose such sensitivity. We take the nearby Fe I 5395.2 A line as example of the latter and analyze the formation of both lines in detail to demonstrate and explain granular Doppler brightening. We show that this affects all narrow lines. Neither the chromosphere nor Mg II h & k play a role, nor is it correct to describe the activity sensitivity of Mn I 5394.7 A through plage models with outward increasing temperature contrast. The Mn I 5394.7 A line represents a proxy diagnostic of strong-field magnetic concentrations in the deep solar photosphere comparable to the G band and the blue wing of H-alpha, but not a better one than these. The Mn I lines are more promising as diagnostic of weak fields in high-resolution Stokes polarimetry.Comment: 12 pages, 8 figures, accepted by A&

Flux penetration in slab shaped Type-I superconductors

We study the problem of flux penetration into type--I superconductors with high demagnetization factor (slab geometry).Assuming that the interface between the normal and superconducting regions is sharp, that flux diffuses rapidly in the normal regions, and that thermal effects are negligible, we analyze the process by which flux invades the sample as the applied field is increased slowly from zero.We find that flux does not penetrate gradually.Rather there is an instability in the process and the flux penetrates from the boundary in a series of bursts, accompanied by the formation of isolated droplets of the normal phase, leading to a multiply connected flux domain structure similar to that seen in experiments.Comment: 4 pages, 2 figures, Fig 2.(b) available upon request from the authors, email - [email protected]

The Spatial and Temporal Expression Patterns of Integrin α9β1 and One of Its Ligands, the EIIIA Segment of Fibronectin, in Cutaneous Wound Healing

The fibronectins (FN) comprise a family of adhesive extracellular matrix proteins thought to mediate important functions in cutaneous wounds. Plasma fibronectin (pFN) extravasates for days from intact hyperpermeable vessels following injury whereas mRNAs encoding the cellular fibronectins (cFN) that include two segments, termed EIIIA (EDA) and EIIIB (EDB), are expressed by wound cells. Wounds in mice null for pFN appear to heal normally whereas those in EIIIA null mice exhibit defects, suggesting that cFN may play a role when pFN is missing. Integrin α9β1, a receptor for several extracellular matrix proteins as well as the EIIIA segment, is expressed normally in the basal layer of squamous epithelia. We report results from immunohistochemistry on healing wounds demonstrating that EIIIA-containing cFN are deposited abundantly but transiently from day 4 to 7 whereas EIIIB-containing cFN persist at least through day 14. Elevated expression of α9β1 is seen in basal and suprabasal epidermal keratinocytes in wounds. The spatial expression patterns of cFN and α9β1 are distinct, but overlap in the dermal–epidermal junction, and both are expressed contemporaneously. These observations suggest a role for α9β1–EIIIA interactions in wound keratinocyte function

Changes in standard of candidates taking the MRCP(UK) Part 1 examination, 1985 to 2002: Analysis of marker questions

The maintenance of standards is a problem for postgraduate medical examinations, particularly if they use norm-referencing as the sole method of standard setting. In each of its diets, the MRCP(UK) Part 1 Examination includes a number of marker questions, which are unchanged from their use in a previous diet. This paper describes two complementary studies of marker questions for 52 diets of the MRCP(UK) Part 1 Examination over the years 1985 to 2001 to assess whether standards have changed