3,335 research outputs found
The Effect of Hypertonic Solutions on Development
Post-diapause eggs of Melanoplus differentialis, previously kept at 5° C. for two months (to break the diapause or blocked condition) were placed in aerated balanced salt solutions of varying concentrations (the NaCl content ranging from .9% to 18%)
Land Management Decisions and Agricultural Productivity in the Hillsides of Honduras
Increasing land degradation and concomitant low agricultural productivity are important determinants of rural poverty in the hillside areas of Honduras. Using data at the levels of the farm household, parcel and plot, we develop an econometric modeling framework to analyze land management decisions and their impact on crop productivity. Our econometric model allows for endogenous household decisions regarding livelihood strategy choice, use of labor and external inputs, and participation in organizations. We found support for the inverse farm size-land productivity relationship which suggests that improved land access could increase total crop production. Land tenure has no impact on crop productivity, but adoption of soil conservation practices is higher on owner-operated than leased plots. Ownership of machinery and equipment and livestock ownership both positively influence crop productivity. Education positively affects perennial crop productivity. The gender of the household head has no significant effect on crop productivity, but does influence some land management and input use decisions. Even though household participation in training programs and organizations has only limited effects on crop productivity, agricultural extension plays a key role in promoting adoption of soil conservation practices. Location assets have limited impacts on crop productivity but do influence land management decisions. Road density and better market access have a positive effect on perennial crop productivity. Population density has limited direct impact on crop productivity, though it may have indirect effects by affecting farm size and livelihood strategies.agricultural productivity, hillsides, Honduras, land management, soil conservation, Land Economics/Use, Productivity Analysis,
Simplified Method for Efficient Intravascular Inoculation of Chicken Embryos
The simple syringe-stabilizer unit described in this note provides a means for rapid intravascular inoculation of embryonated chicken eggs with minimal embryonic death from vascular trauma
Are Regions Important in British Elections? Valence Politics and Local Economic Contexts at the 2010 General Election
Pattie C. J., Johnston R. J., Schipper M. and Potts L. Are regions important in British elections? Valence politics and local economic contexts at the 2010 General Election, Regional Studies. Electoral support for major parties is influenced by judgements of economic performance. This helps account for electoral geographies, as economic conditions vary spatially. Past work, concentrating on objective economic indicators or on voters' personal economic evaluations, suggested that contextual effects work most powerfully when very local, suggesting that regional voting trends are artefacts of more intimate geographies. This paper extends that work by examining how voters' decisions are influenced by the economic evaluations of others in their communities and demonstrates that some contextual effects, at least, really are more powerful at the regional than at more local scales
The Axis-Ratio Distribution of Galaxy Clusters in the SDSS-C4 Catalog as a New Cosmological Probe
We analyze the C4 catalog of galaxy clusters from the Sloan Digital Sky
Survey (SDSS) to investigate the axis-ratio distribution of the projected two
dimensional cluster profiles. We consider only those objects in the catalog
whose virial mass is close to 10^{14}h^{-1}M_{sun}, with member galaxies within
the scale radius 1000 kpc. The total number of such objects turns out to be
336. We also derive a theoretical distribution by incorporating the effect of
projection onto the sky into the analytic formalism proposed recently by Lee,
Jing, & Suto. The theoretical distribution of the cluster axis-ratios is shown
to depend on the amplitude of the linear power spectrum (sigma_8) as well as
the density parameter (Omega_{m}). Finally, fitting the observational data to
the analytic distribution with Omega_{m} and sigma_{8} as two adjustable free
parameters, we find the best-fitting value of sigma_{8}=(1.01 +/-
0.09)(Omega_{m}/0.6)^{(0.07 +/- 0.02) +0.1 Omega_{m}}$. It is a new
sigma_{8}-Omega_{m} relation, different from the previous one derived from the
local abundance of X-ray clusters. We expect that the axis-ratio distribution
of galaxy clusters, if combined with the local abundance of clusters, may put
simultaneous constraints on sigma_{8} and Omega_{m}.Comment: accepted for publication in ApJ, 17 pages, 3 figures, improved
analysis, more discussion on the validity and the caveats of the mode
Detection of Overhead Contact Lines with a 2D-Digital-Beamforming Radar System for Automatic Guidance of Trolley Trucks
The benefit of trolley truck systems is the substitution of the diesel fuel by the cheaper and more ecological electrical energy. Trolley trucks are powered by electricity fromtwo overhead contact lines, where one is the supply and the other the return conductor. Such trolley trucks are used for haulage at open pit mining sites but could also be used for freight traffic at roadways in the future. Automatic guidance prevents the trolley-powered trucks fromleaving the track and thus allows higher operating speeds, higher loading capacity, and greater efficiency. Radar is the ideal sensing technique for automatic guidance in such environments.The presented radar systemwith two-dimensional digital beamforming capability offers a compact measurement solution as it can be installed on top of the truck. Besides the distance measurement, this radar system allows to detect the location and inclination of the overhead contact lines by digital beamforming in two dimensions. Besides automatic guidance, the knowledge of the inclination of the overhead contact lines could allow automatic speed adaption, which would help to achieve maximum speed especially in hilly terrain
Niet schieten is altijd mis : mogelijkheden ter voorkoming van kraaienschade in de fruitteelt
Als nadere uitwerking van aanbevelingen uit een eerder verschenen rapport zijn bruikbare afweermiddelen ter voorkoming van kraaienschade in de fruitteelt onderzoch
Self-perceived oral health and orofacial aesthetics of cleft patients
Purpose: To evaluate the self-perceived oral health and aesthetics of the dentition and jaw in patients with different types of oral cleft, measured by patient-reported outcome measures (PROMs). Additionally, to compare the results of the PROMs between cleft lip and or/palate (CL/P) patients and non-affected controls. Methods: 420 CL/P patients treated at the cleft team of the Erasmus Medical Center, Rotterdam, The Netherlands, were included, and 138 non-cleft patients were recruited as control-group. Patient’s perceptions were retrospectively evaluated using the CLEFT-Q Teeth for dental aesthetics at ages 8, 12 and 22, CLEFT-Q Jaw for jaw aesthetics at ages 12 and 22, and the Child Oral Health Impact Profile—Oral Symptoms Subscale (COHIP-OSS) for oral health at ages 8 and 12. One-way ANOVA was used to compare differences in oral health and aesthetic perceptions among age-groups, cleft types, as well as between cases and controls. Results: CL/P patients were significantly less satisfied than controls with their dental aesthetics (p = 0.001). CL/P patients reported significantly lower satisfaction on CLEFT-Q Teeth scores at ages 8 and 12, than at 22 years (p < 0.001). Patients with the most extensive cleft phenotype, Cleft Lip and Palate (CLAP), reported lowest satisfaction on the CLEFT-Q Teeth. No differences in perceptions of oral health nor in aesthetics of the jaw were found in the different cleft types, ages, nor in study versus control group. Conclusion: This study found differences in self-perceived dental aesthetics: CL/P patients are less satisfied than non-affected controls. CLAP patients are least satisfied, but satisfaction increases with age.</p
- …