4,765 research outputs found
Strong nonnegativity and sums of squares on real varieties
Motivated by scheme theory, we introduce strong nonnegativity on real
varieties, which has the property that a sum of squares is strongly
nonnegative. We show that this algebraic property is equivalent to
nonnegativity for nonsingular real varieties. Moreover, for singular varieties,
we reprove and generalize obstructions of Gouveia and Netzer to the convergence
of the theta body hierarchy of convex bodies approximating the convex hull of a
real variety.Comment: 11 pages, 4 figure
Physiological investigations of the response of wheat (Triticum aestivum L.) to soil salinity
PhD ThesisA series of greenhouse and control environment experiments
were carried out to study the response of some wheat cultivars (Triticum
aestivum L. ) to soil salinity.
The rate and percentage of seed germination were reduced
by increasing soil salinity. The cultivar Falchetto was more tolerant
in terms of germination than the other cultivars under saline
conditions.
Increasing salinity consistently reduced the growth and dry
matter production of all wheat cultivars used. The most sensitive
growth character to salinity was leaf area and tiller number while
net assimilation rate was least sensitive and sometimes not affected
by salinity. The retardation of growth under salt stress in this study
may result from reduced leaf area for photosynthesis, but the cause
of reduced leaf area is not clear.
In all cultivars tested, grain yield and its components were
reduced by increasing soil salinity (0 - 0.6% salt) or irrigation with
saline water (0 - 4000 ppm salt). The most sensitive yield characters
to salinity were spike number and grain number per spike while spike
length and spikelet number per spike were less sensitive as compared
with the other components. Falchetto and Shakha 62 were less sensitive
than the other cultivars used in this study.
Leaf proline content increased while leaf chlorophyll content
decreased with increasing soil salinity. Also, leaf and stem content
of sodium, calcium and magnesium increased with increasing salinity
levels both in vegetative parts and in grains. Increasing soil
salinity increased ash and protein content of wheat grains but
decreased moisture and total carbohydrate content.
Application of nitrogen fertilizer under saline conditions
enhanced grain yield and its components and to some extent countered
the adverse effect of soil salinity up to 0.4%. While added nitrogen
did not increase growth and dry weight of wheat plant significantly,
crop growth rate increased significantly. On the other hand spraying
wheat crop with trace elements did not affect the growth and grain
yield and its components except 1000 kernel weight under saline
conditions.
The interaction effect between salinity and some environmental
factors was significant on germination and growth. Under saline and
non-saline conditions increasing temperature from 10 to 20°C increased
germination capacity and depressed it between 20 and 30°C. Also,
increased relative humidity from 47 to 92% increased germination
capacity. For vegetative growth, generally, increasing temperature up
to 20°C, relative humidity from 47 to 92%, and available soil water
content from 20 to 100% increased vegetative growth and dry matter
production of wheat plant under saline and non-saline conditions.
The interaction effect between salinity and presoaking with
plant growth regulators (CCC, GA3, IAA and Kinetin) and salt solutions
(Nacl and Cacl2 ) on germination and growth of wheat accelerated
germination under saline and non-saline conditions. For some
characters presoaking with these plant growth regulators or salt reduced
the deleterious effect of salinity and improved plant performance at
these early stages of growth under saline conditions.
Water and osmotic potentials, total and relative water
content (RWC) and transpiration rate decreased and stomatal number
per microscope field increased with increasing soil salinity, but
turgor potential was essentially unchanged by increasing soil salinity
indicating osmotic adjustment. Also, it is evident from the water
relations, PEG and RH experiments that ion toxicity effect operated
in addition to the osmotic one during early stages of growthEgyptian Government
Empowering professional syndicates in Egypt to achieve good governance; An application to the Egyptian Medical Syndicate
In searching for a governance reform strategy, the size, the vital roles of professional syndicates and their impact on the whole society place them among our top priorities. According to both the old and the new Egyptian constitutions, the professional syndicates have the legal base to represent the different professions, defend rights and interests of their members, improve the quality of the offered services to the society, and share in creating policies and procedures related to syndicates\u27 members and their careers. The discrepancy between the proposed role of the professional syndicates and the reality motivated this research into the reasons behind their weaknesses and poor performance. Little recent analysis of Egypt\u27s syndicates could be found in the literature. Selecting the Egyptian Medical Syndicate (EMS) as a case study was invoked by its vital role in health system reform. The main research question is “To what extent do the governance structure and procedures of the Egyptian Medical Syndicate correspond to international good governance standards? The qualitative method was adopted in this research. The aspects of the governance of the Canadian Medical Association (CMA) were used as a guide to highlight what components and core compositions of the structures of the EMS should be examined in the governance process and how? In addition, two questionnaires were developed. The first one conducted to the members and the later to senior managers and Board members. The respondents answered these questionnaires through group interview for members and Individual In-Depth Interview for senior managers and Board members. The aim was to make sure through these instruments, it will be possible to assess to what extent the EMS covered the standards principles of good governance and illuminate the areas which need to be improved. The study targeted doctors in three Egyptian governorates (Cairo, Giza and Gharbia) and the sample included males and females from different ages and backgrounds. The research found that the current governance system and procedures are in a bad need to be reformed to be consistent with international good governance standards. The findings of the study illustrated that there is a crucial need to issue a new law and bylaw for the Egyptian Medical Syndicate. The elections’ system needs to be revised. There is a necessity to identify a clear vision and mission for the EMS, setting the long term objectives, consider the annual planning and evaluation for the programs and activities. The Board of Directors needs to enhance its leadership and strategic planning skills. The study also highlighted the importance of considering the new tools of communications such as emails, website and video conferences to share information, and to achieve greater connection, participation and involvements for the members of the EMS. This study open the door to further research with hope to develop a good model to evaluate the governance system in other professional syndicates, and it will be possible to apply the model with some adaptation to fit the specific features of each syndicate
Somali Demining Action Group
Somali Demining Action Group (SDAG) aims to eradicate anti-personnel landmines in Central and south Somalia. Statistics are provided for mine casualties in central and south Somalia
- …