Greater Head Research Articles

An unconfined groundwater model of the Death Valley Regional Flow System and a comparison to its confined predecessor

Summary The MODFLOW version of the United States Geological Survey (USGS) Death Valley Regional Flow System (DVRFS) in California and Nevada is conceptually inaccurate in that it models an unconfined aquifer as a confined system and does not accurately simulate unconfined drawdown in transient pumping simulations. The transfer of geologic and hydrologic information from the confined MODFLOW DVRFS model to an unconfined MODFLOW–SURFACT (SURFACT) version was accomplished by maintaining cell structure between models and computing effective cell properties to translate the HUF2 package used in MODFLOW to the BCF4 package used by SURFACT. The confined version of the DVRFS was compared to the unconfined SURFACT version by examining head contour maps and the ability of the SURFACT model to match the 4900 observations of hydraulic head/drawdown, 49 observations of groundwater discharge, and 15 estimates of groundwater fluxes into/out of the model domain. Resultant weighted root mean squared error (ωRMSE) for the unconfined SURFACT model was lower than the USGS confined model. Despite a lower ωRMSE, unconfined conditions simulated with SURFACT did produce greater heads in mountainous regions compared to the confined MODFLOW with differences most pronounced in regions where cell thickness is large, horizontal conductivity small and recharge large. Difference in computed heads reflects computation schemes employed by both models to estimate interblock conductance. Specifically, interblock conductance for the unconfined SURFACT model is dependent on the relative saturation of a modeled cell while MODFLOW’s confined system is not. Despite head differences, SURFACT simulates comparable flux estimates to MODFLOW (e.g. observed ET, groundwater spring flow, and groundwater flux across model boundaries), while significantly improving transient well drawdown estimates. SURFACT is also capable of producing more realistic estimates of water availability from proposed groundwater development and resultant potential impacts to the region.

Onion thrips (Thrips tabaciLindeman) damage on early white cabbage grown under mulch and non-mulch conditions

In 2005 the damage caused by onion thrips (Thrips tabaci) on a susceptible hybrid of early cabbage (cv. ‘Parel’) was studied in a block field experiment. The cabbage was grown in four treatments: 1) on non-mulched surfaces, 2) on surfaces mulched with barley straw, 3) on surfaces mulched with hay and 4) on surfaces mulched with black PE mulch. The trial consisted of two parts: the first part included plots that were mulched as indicated from the very beginning (normal), while in the second part the soil was first covered with black PE mulch for about one month, than this was removed and replaced either by organic mulches or left non-mulched (postponed). In this way, we wanted to diminish the yield loss because of low temperatures and abundant precipitation. Under cold and wet conditions in spring which led to late appearance and low levels of the pest, the growing of cabbage under black PE mulch proved most effective and these plants exhibited the greatest head mass as well as the greatest net mass, altho...

Comparing the effect of habitat on the magnitude of inbreeding depression in the Mediterranean native Senecio malacitanus and the alien S. inaequidens: consequences for invasive ability

We studied the effects of inbreeding depression and the level of self-compatibility on overall fitness parameters in the invasive species Senecio inaequidens DC. and the native Senecio malacitanus Huter, in plots with and without interspecific competition by natural vegetation. Competition had a stronger effect on fitness parmeters for both species, but it mostly affected the survival of S. malacitanus during the first year, and particularly the survival of individuals issued from inbred crosses. Inbreeding depression decreased the seed production in both species. Summer drought in the second year reduced the fitness of all inbreeding levels, masking the effect of inbreeding.The alien species had a shorter pre-reproductive time, a greater head production, and greater resistance to competition from established vegetation. In addition, a negative relationship was found between inbreeding coefficient and herbivory in the native species only. All these factors may help to explain the invasive ability of S. inaequidens. The magnitude of inbreeding depression and the environmental conditions can thus determine the success or failure of an invasion.

Effect of foliar urea application on quality, growth, mineral uptake and yield of broccoli (Brassica oleracea L., var. italica)

The objective of this study was to determine the effect of foliar urea applications on quality, growth, mineral content and yield of broccoli under field conditions in 2003, 2004 and 2005. Broccoli cultivars AG 3317 and AG 3324 were treated with foliar urea applications at different concentrations (0.0, 0.4, 0.8 and 1.0%). Foliar applications of urea, especially 0.8 and 1.0% resulted in larger heads, weightier heads and plants as well as higher plants. Conversely, the greatest head and leaf dry matter contents were obtained with no fertilizer-nitrogen application. SPAD chlorophyll readings that were measured in the third year increased with elevated urea concentrations. In regard to the nutrient content, it can be interfered that soil nitrogen fertilization and foliar urea applications increased the content of almost all nutrients in leaves and heads of both broccoli cultivars in three experiment years. Generally, the greatest values were obtained from 1.0% urea application for both cultivars. It results from the study that for optimum yields 0.61 and 0.96% concentrations of urea sprays could be successfully used to obtain better growth and yield in broccoli cultivars AG 3317 and AG 3324, respectively.

Laboratory Assessment of Altered Atmospheric Carbon Dioxide on Filamentous Green Algae Phenolic Content and Caddisfly Growth and Survival

ABSTRACT To test global change effects on lentic ecosystems, we examined I) if algae phenolic content was influenced by CO2 treatments, and 2) if algivores fed CO2-treated algae were impacted. Four common Chlorophytes (Cladophora glomerata, Spirogyra grevilleana, Ulothrix, fimbriata, and Zygnema sp.) were grown under three atmospheric carbon dioxide environments (200, 360, and 3000 mg/L). Algivore (the microcaddisfly Hydroptila waubesiana [Trichoptera: Hydroptilidae]) feeding assays, using identically treated algae (C. glomarata and U. fimbriata) as a food source, were run in parallel. Generally, Folin-Denis reactive phenolics were highest among algae grown under high CO2 treatments, intermediate at ambient CO2, and lowest under low CO2 treatment. Differential species responses in reactive phenolics were observed, with U. fimbriata being most responsive (∼6 %) to CO2 enrichment, and C. glomarata being unresponsive (<1%). Regardless of algal species or CO2 treatment, developmental rates of H. wauhesiana larvae to mid and late instars were statistically identical. Percent survival for larvae given U. fimbriata and C. glomerata were similar; however, survival rates were higher when larvae were fed low CO2 treated U. fimbriata. For larvae fed C. glomerata, the general trend was that larvae fed algae grown at high CO2 levels had the greatest head capsule width; those fed algae at low CO2 levels had the greatest head capsule length and pronotal length. In contrast, larvae fed U. fimbriata had the largest head capsule widths under ambient CO2 levels, the largest head capsule widths under high levels, and had equal pronotal lengths at all CO2 levels. Larvae fed C. glomerata grown under ambient conditions produced portable cases of the greatest length at the experiment's conclusion, but no distinct trend was seen for larvae fed U. fimbriata. Overall, CO2 induced production of reactive phenolics in chlorophytes did not appreciably influence herbivorous microcaddisfly development or survival.

PLANTAR PRESSURE REDISTRIBUTION AFTER A HIGH AND LOW UNLOAD

The plantar soft tissue is the primary means of physical interaction between a person and the ground during locomotion. Dynamic loads greater than body weight are borne across the entire plantar surface during each step. However, most testing of these tissues has concentrated on the structural properties of the heel pad. The purpose of this study was to determine the material properties of the plantar soft tissue from six locations beneath: the great toe (subhallucal), the 1st, 3rd and 5th metatarsal heads (submetatarsal), the lateral midfoot (lateral submidfoot) and the heel (subcalcaneal). We obtained specimens from these locations from 11 young, non-diabetic donors; the tissue was cut into 2 cm×2 cm blocks and the skin was removed. Stress relaxation experiments were conducted and the data were fit using the quasi-linear viscoelastic (QLV) theory. To determine tissue modulus, energy loss and the effect of test frequency, we also conducted displacement controlled triangle waves at five frequencies ranging from 0.005 to 10 Hz. The subcalcaneal tissue was found to have an increased relaxation time compared to the other areas. The subcalcaneal tissue was also found to have an increased modulus and decreased energy loss compared to the other areas. Across all areas, the modulus and energy loss increased for the 1 and 10 Hz tests compared to the other testing frequencies. This study is the first to generate material properties for all areas of the plantar soft tissue, demonstrating that the subcalcaneal tissue is different than the other plantar soft tissue areas. These data will have implications for foot computational modeling efforts and potentially for orthotic pressure reduction devices.

The compressive material properties of the plantar soft tissue

The plantar soft tissue is the primary means of physical interaction between a person and the ground during locomotion. Dynamic loads greater than body weight are borne across the entire plantar surface during each step. However, most testing of these tissues has concentrated on the structural properties of the heel pad. The purpose of this study was to determine the material properties of the plantar soft tissue from six locations beneath: the great toe (subhallucal), the 1st, 3rd and 5th metatarsal heads (submetatarsal), the lateral midfoot (lateral submidfoot) and the heel (subcalcaneal). We obtained specimens from these locations from 11 young, non-diabetic donors; the tissue was cut into 2 cm×2 cm blocks and the skin was removed. Stress relaxation experiments were conducted and the data were fit using the quasi-linear viscoelastic (QLV) theory. To determine tissue modulus, energy loss and the effect of test frequency, we also conducted displacement controlled triangle waves at five frequencies ranging from 0.005 to 10 Hz. The subcalcaneal tissue was found to have an increased relaxation time compared to the other areas. The subcalcaneal tissue was also found to have an increased modulus and decreased energy loss compared to the other areas. Across all areas, the modulus and energy loss increased for the 1 and 10 Hz tests compared to the other testing frequencies. This study is the first to generate material properties for all areas of the plantar soft tissue, demonstrating that the subcalcaneal tissue is different than the other plantar soft tissue areas. These data will have implications for foot computational modeling efforts and potentially for orthotic pressure reduction devices.

Thirty-two millimetre heads and accelerated polyethylene wear in total hip arthroplasty

In total hip arthroplasty 32 mm heads are often used as the greater diameter is thought to contribute to improved stability. However, greater head diameter can also lead to greater volumetric wear. We compared polyethylene wear between patients with 32 mm heads and those with smaller heads. All patients who had Harris Galante1 metal-backed, uncemented cups inserted between 1986 and 1996 at our institute were annually reviewed clinically and radiographically. Accelerated polyethylene wear was noted between the fifth and seventh postoperative year in 17 out of 165 total hip replacements with 32 mm heads, but only in 21 out of 961 total hip arthroplasties with smaller femoral heads. In all 17 THRs, accelerated wear was also associated with thin polyethylene (<6 mm). This paper highlights a potentially serious problem. When 32 mm metal heads are used with uncemented cups and polyethylene liners, there is a risk of accelerated acetabular wear in patients with thin polyethylene.

Examining the Role of Surfactant Packing in Phase Transformations of Periodic Templated Silica/Surfactant Composites

In this work, we examine the role of curvature and surfactant packing in controlling the structure of periodic silica/surfactant composites by driving such materials through a transformation from a hexagonal to a lamellar phase. We focus on how the interplay of desired packing and volume constraints dictates the resulting structures. In general, surfactants expand in a complex way upon heating, and this can cause a change in the optimal packing geometry. However, the presence of a rigid silica framework may prevent surfactants from reaching this preferred volume and/or curvature. Real-time in situ X-ray diffraction is used to monitor the structural evolution of these materials heated under hydrothermal treatments. Because the thermal-driven disorder of the surfactant tails drives the phase transition, we examine four types of composites with varying tail density. Ordinarily, composites consist of surfactants with one 20-carbon tail and one positively charged ammonium headgroup. Tail density is varied by replacing a small amount (0-16%) of these single-tail, single-head surfactants with single-tail, double-head 'gemini' surfactants. A greater head--tail ratio indeed produces different results, causing the phase transition to occur at higher temperatures. Using simple geometric models to gain better understanding of our experimental results, we find that, while both unfavorable curvature and limited volume may exist for the surfactants in these composites, the constrained curvature appears to be the dominant effect in driving structural rearrangement.

The influence of pool length on local turbulence production and energy slope: a flume experiment

AbstractThe influence of pool length on the strength of turbulence generated by vortex shedding was investigated in a 6 m long recirculating flume. The experiment utilized a 38% constriction of flow and an average channel‐bed slope of 0·007. The base geometry for the intermediate‐length pool experiment originated from a highly simplified, 0·10 scale model of a forced pool from North Saint Vrain Creek, Colorado. Discharge in the flume was 31·6 l/s, which corresponds to a discharge in the prototype channel of 10 m3/s. Three shorter and four longer pool lengths also were created with a fixed bed to determine changes in turbulence intensities and energy slope with pool elongation. Three‐dimensional velocities were measured with an acoustic Doppler velocimeter at 31–40 different 0·6‐depth and near‐bed locations downstream of the rectangular constriction. The average velocity and root mean square (RMS) of the absolute magnitude of velocity at both depths are significantly related to the distance from the constriction in most pool locations downstream of the constriction. In many locations, pool elongation results in a non‐linear change in turbulence intensities and average velocity. Based on the overall flow pattern, the strongest turbulence occurs in the center of the pool along the shear zone between the jet and recirculating eddy. The lateral location of this shear zone is sensitive to changes in pool length. Energy slope also was sensitive to pool length due to a combination of greater length of the pool and greater head loss with shorter pools. The results indicate some form of hydraulic optimization is possible with pools adjusting their length to adjust the location and strength of turbulent intensities in the center of pools, and lower their rate of energy dissipation. Copyright © 2004 John Wiley &amp; Sons, Ltd.

Response of two sunflower hybrids to planting dates and densities

This investigation was carried out at the Experimental Farm of Assiut University during the summers of 2000 and 2001 to study the responses of two sunflower hybrids (Vidoc and Euroflora) to planting dates (May 1st, June 1st and July 1st) and planting densities (55,533, 83,300 and 166,600 plants/ha). The results indicated that the two varieties differed highly significantly in all studied traits except oil yield/ha. The highest seed yield (3.64 t/ha) was obtained with the variety Vidoc. In addition, the results revealed that the planting date exerted a highly significant influence on all vegetative growth traits along with yield and its components. Increasing plant density increased the seed and oil yield/ha. By contrast, the stem diameter, head diameter, 100-seed weight and seed yield/plant decreased with increasing plant density. The interaction between varieties and plant density had a highly significant effect on head diameter. The greatest head diameter (20.06 cm) was recorded for the variety Vidoc planted at lower density. Concerning the interaction between planting density and planting date, the highest seed yield (4.47 t/ha) was obtained from dense plants at the early sowing date, and the highest oil % (45.32) at the late planting date and the lowest plant density. The second order interaction exerted a highly significant influence on stem and head diameter in addition to seed yield/plant, where the highest value (78.13 g/plant) was obtained with the variety Vidoc planted on May 1st at the lowest plant density.

Robert Insall

Robert Insall

Coastal karst springs in the Mediterranean basin : study of the mechanisms of saline pollution at the Almyros spring (Crete), observations and modelling

Variations in salinity and flow rate in the aerial, naturally salty spring of Almyros of Heraklion on Crete were monitored during two hydrological cycles. We describe the functioning of the coastal karstic system of the Almyros and show the influence of the duality of the flow in the karst (conduits and fractured matrix) on the quality of the water resource in the coastal area. A mechanism of saltwater intrusion into this highly heterogeneous system is proposed and validated with a hydraulic mathematical model, which describes the observations remarkably well.

The Public Service Ethos: Decline and Renewal?

This article examines the two principal means by which ethically based standards of conduct can be secured in public administration. The first approach, advocated by Carl Friedrich in the 1940s, places the primary emphasis on the values and self-directed willingness of the public servant to act in the public interest. This reliance on a public service ethos was to some extent the hallmark of the British Civil Service before the post-1979 managerial and organisational changes and was a product of the exemplary leadership of two great heads of the home civil service, Sir Warren Fisher and Sir Edward Bridges. It will be argued that marketization, managerialism and organisational down-sizing in the public services have created a culture whose values (risk-taking, short-term profits and efficiency gains) greatly threaten the existence of the public service ethos. Consequently, the only effective way to secure any semblance of the public interest and to deter impropriety lies in the second approach - that is to place a much greater emphasis on external monitoring and legally based sanctions and safeguards. This alternative approach was advocated by Herman Finer, a contemporary of Karl Friedrich. The legal protection given by the 1998 Public Interest Disclosure Act to ‘whistle blowers’ should be seen as a welcome step in this direction. Greater precision in the wording of the Civil Service Code and a strengthening of its inadequate enforcement mechanism would, it is argued, further help to protect endangered public service values within the Civil Service.

INFLUENCE OF FRESHWATER FLOW REGIME ON FISH ASSEMBLAGES IN THE GREAT FISH RIVER AND ESTUARY

Summary Two and a half years of data were collected from the lower Great Fish River, head region and estuary to determine the fish species composition within these areas. Gilchristella aestuaria, Liza dumerilii, Rhabdosargus holubi and Pomadasys commersonnii were the four most abundant species captured, with riverine flow rate having an important effect on both species composition and numbers of fishes in the different regions. Most marine species displayed a strong inverse relationship between catch per unit effort and elevated freshwater inputs. Euryhaline marine species dominated the catches at all sampling sites during low flows but were less common during high flow periods when catadromous species were most abundant. Based on the available evidence it is suggested that for most marine species in the river this decline in abundance is related to low conductivity levels following floods rather than avoidance of elevated flows. The impact of elevated suspensoid concentrations and lowered dissolved oxyge...

DISTRIBUTION PATTERNS OF FISHES IN AN EASTERN CAPE ESTUARY AND RIVER WITH PARTICULAR EMPHASIS ON THE EBB AND FLOW REGION

SUMMARY Two and a half years of data were collected from the Great Fish River (>1%‰), head(1–4%‰) and estuary (>4%‰) using seine and gill nets to determine the fish species composition within these regions. Euryhaline marine taxa belonging to the families Mugilidae and Sparidae dominated the catch in all three regions. Gilchristella aestuaria was the single most common estuarine resident, and several marine species were captured in freshwater for the first time. The cichlid Oreochromis mossambicus was the most common freshwater species but was only abundant in riverine samples. Catches made with the gill nets and large seine net both indicated that the densities of fish were higher at the head than in either the river or the estuary. Since the highest levels of suspended particulate organic matter in the Great Fish estuary are known to be in the head region, the highest densities of fishes would be expected from the same area. Physical parameters were also measured to ascertain some of the possible factor...

Whatʼs Your Feedback Style?

Ruth I. Hansten, RN, MBA, and Marilynn Washburn, RN, MA, are health-care consultants on Bainbridge Island, WA, who conduct nursing and management workshops. Since December of 1990, they have led nearly 100 clinical delegation-skills seminars in six states. Their seminar is a collaborative effort with Loretta O'Neill, RN, MN, and the Washington Organization of Executives, Seattle. The authors have also developed a learning module, Managerial Delegation, for the University of Phoenix in Arizona. Ruth Hansten was named a Great Head Nurse by her co-workers in AJN'sJanuary 1989 article. right, do it yourself! c. Leave a note for the nurse manager saying, Jo just-isn't working out. d. Review the order sheet with Jo, noting that today the unit is short of certain supplies, and ask her if she needs further instruction.

Saluting Great Head Nurses

Saluting Great Head Nurses

Great Head Nurses

Great Head Nurses

BEHAVIORAL AND PHYSIOLOGICAL RESPONSES TO SPATIAL NOVELTY IN DAIRY COWS

Thirty-two lactating Holstein cows were used in a study of excitability and agonistic behavior of dairy cattle. When cattle were moved from a familiar stall to an unfamiliar place, heart rate immediately increased on average from 83.2 to 107.8 (P &lt; 0.01). The total distance of head movement in a novel environment varied considerably. The animal with the greatest head movement had a distance 6.6 times larger than the cow with the least head movement. Significant deviation from the mean values of agonistic interactions were found for 28 cows: of these 10 showed tendencies for physical attacks (P &lt; 0.05), 5 for threats (P &lt; 0.05), 6 for displacement of physical attacks (P &lt; 0.05), and 7 showed significant tendencies for avoidance when threatened (P &lt; 0.05). Both the instigator and victim cows that showed a higher proportion of the psychological form of agonistic behavior also tended to show a larger amount of head movement with less variation, lower increase in heart rate, and less change in norepinephrine concentration due to transfer. The results indicate that analyses of head movement patterns may be used for an assessment of excitability of cows. Key words: Cow, behavior, spatial novelty, head movement, excitability, temperament