Apomixis, the formation of asexual seeds in plants, leads to populations that are genetically uniform maternal clones. The transfer of apomixis to crop plants holds great promise in plant breeding ...for fixation of heterozygosity and hybrid vigour because it would allow the propagation of hybrids over successive generations. Apomixis involves the production of unreduced (diploid) female gametes that retain the genotype of the parent plant (apomeiosis), followed by parthenogenetic development of the egg cell into an embryo and the formation of functional endosperm. The molecular mechanisms underlying apomixis are unknown. Here we show that mutation of the Arabidopsis gene DYAD/SWITCH1 (SWI1) a regulator of meiotic chromosome organization, leads to apomeiosis. We found that most fertile ovules in dyad plants form seeds that are triploid and that arise from the fertilization of an unreduced female gamete by a haploid male gamete. The unreduced female gametes fully retain parental heterozygosity across the genome, which is characteristic of apomeiosis. Our results show that the alteration of a single gene in a sexual plant can bring about functional apomeiosis, a major component of apomixis.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Understanding the burden and pattern of mental disorders as well as mapping the existing resources for delivery of mental health services in India, has been a felt need over decades. Recognizing this ...necessity, the Ministry of Health and Family Welfare, Government of India, commissioned the National Mental Health Survey (NMHS) in the year 2014-15. The NMHS aimed to estimate the prevalence and burden of mental health disorders in India and identify current treatment gaps, existing patterns of health-care seeking, service utilization patterns, along with an understanding of the impact and disability due to these disorders. This paper describes the design, steps and the methodology adopted for phase 1 of the NMHS conducted in India. The NMHS phase 1 covered a representative population of 39,532 from 12 states across 6 regions of India, namely, the states of Punjab and Uttar Pradesh (North); Tamil Nadu and Kerala (South); Jharkhand and West Bengal (East); Rajasthan and Gujarat (West); Madhya Pradesh and Chhattisgarh (Central) and Assam and Manipur (North East). The NMHS of India (2015-16) is a unique representative survey which adopted a uniform and standardized methodology which sought to overcome limitations of previous surveys. It employed a multi-stage, stratified, random cluster sampling technique, with random selection of clusters based on Probability Proportionate to Size. It was expected that the findings from the NMHS 2015-16 would reveal the burden of mental disorders, the magnitude of the treatment gap, existing challenges and prevailing barriers in the mental-health delivery systems in the country at a single point in time. It is hoped that the results of NMHS will provide the evidence to strengthen and implement mental health policies and programs in the near future and provide the rationale to enhance investment in mental health care in India. It is also hoped that the NMHS will provide a framework for conducting similar population based surveys on mental health and other public health problems in low and middle-income countries.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Laser boriding technique was used to form boride layers on EN25 steel. The main aim of this current study is to form the hard laser borided layer on the low alloy steel surface and analyze the effect ...of process parameters on borided layer hardness, depth, and width. The properties and microstructure (micro-hardness, boride layer width, and depth) are analyzed after laser boriding process with different laser process parameters (power and speed). The micro-hardness of the boride layer was measured using the Vickers micro-hardness tester. The boride depth and width was measured and captured using a machine vision inspection system. The existence of borides formed in the laser treated layer was confirmed via X-ray diffraction technique. The corrosion rates of the laser borided and as received samples are observed in 3% NaCl solution using Potentiodynamic polarization test. The response surface methodology was used to analyze the effects of power, travel speed on the hardness and the boron layer width and depth. The two-factor three-level full factorial design available in response surface methodology was used to develop the regression model for laser boriding process. A multiobjective optimization technique was used to optimize the laser process parameters to maximize the boron layer width and to minimize the boride layer depth. The validation trail assures that the expected value has good conformant with the actual experimental value.
•It is the first attempt of laser boriding on EN25 (2.5% Ni Cr Mo steel) low alloy steel.•The corrosion rates of the laser borided and as received samples are observed.•The response surface methodology was used to analyze the effects of parameters.•Optimum laser boriding parameters are identified using optimization technique.
Synthetic Clonal Reproduction Through Seeds Marimuthu, Mohan P.A; Jolivet, Sylvie; Ravi, Maruthachalam ...
Science (American Association for the Advancement of Science),
02/2011, Letnik:
331, Številka:
6019
Journal Article
Recenzirano
Cloning through seeds has potential revolutionary applications in agriculture, because it would allow vigorous hybrids to be propagated indefinitely. However, asexual seed formation or apomixis, ...avoiding meiosis and fertilization, is not found in the major food crops. To develop de novo synthesis of apomixis, we crossed Arabidopsis MiMe and dyad mutants that produce diploid clonal gametes to a strain whose chromosomes are engineered to be eliminated after fertilization. Up to 34% of the progeny were clones of their parent, demonstrating the conversion of clonal female or male gametes into seeds. We also show that first-generation cloned plants can be cloned again. Clonal reproduction through seeds can therefore be achieved in a sexual plant by manipulating two to four conserved genes.
This paper presents a new approach for the optimization of drilling parameters on drilling Al/SiC metal matrix composite with multiple responses based on orthogonal array with grey relational ...analysis. Experiments are conducted on LM25-based aluminium alloy reinforced with green bonded silicon carbide of size 25 μm (10% volume fraction). Drilling tests are carried out using TiN coated HSS twist drills of 10 mm diameter under dry condition. In this study, drilling parameters namely cutting speed, feed and point angle are optimized with the considerations of multi responses such as surface roughness, cutting force and torque. A grey relational grade is obtained from the grey analysis. Based on the grey relational grade, optimum levels of parameters have been identified and significant contribution of parameters is determined by ANOVA. Confirmation test is conducted to validate the test result. Experimental results have shown that the responses in drilling process can be improved effectively through the new approach.
Production process optimization has been considered as one of the essential elements in modern metal mines context. Several operations were started to modify with these resources concern, which ...mainly includes machining processes. Various technological developments have been evident in these machining processes including electrical discharge machining. However, due to several limitations of conventional process, powder mixed discharge machining has been brought into the research realm. Recent years, many applications can be found under the mining sector. Despite of various perspectives have been considered but concerning with increase of mining process through optimizing its parameters are limited. In this study, this literature gap has been addressed, with the consideration of optimizing the production process parameters optimization of metal mines, in which concentrations of the reinforcements and peak current are considered as input parameters. The performance of the proposed parameters has been measured with the outputs including surface quality, surface roughness, material removal rate and tool wear rate. Various behavior analysis was done to identify the effective process parameters with resource optimization objective. Totally, ten different combination of process parameters were studied through numerical analysis in addition with experimental studies. Finally, the results revealed that PP2 is the best process parameter for achieving better performance. Further, the necessary future direction to explore more scientific potential on the concern topic has been discussed.
•Optimizing the production process parameters optimization of metal mines.•Behavior analysis was performed to identify the effective process parameters.•Various combinations of process parameters were studied through numerical analysis.
Digital learning is a cost-effective and time-saving approach in higher education. The present study aimed to check the impact of continuing nursing education programs through digital learning by ...connecting Indian nurses to NIMHANS Digital Academy (NDA).
One group pre-test and post-test design was used for this study. Overall, 217 nurses registered for the course and 146 nurses were recruited on the basis of eligibility and their Expression of Interest (EoI) through the online registration portal. All the nurses who had access to the internet and enough internet literacy were included in the study. 64 nurses had not submitted the post-test due to various reasons within the stipulated time. Hence, the final sample achieved and calculated for the analysis was n = 82. The data for this study were collected through the retrospective chart review method.
The findings of this study reveal that most of the nurses in India had willingness and readiness for digital learning. All the nurses who joined the NDA learning program stated that they would like to improve their knowledge regarding mental health and illness, to identify and manage mentally ill patients efficiently. The results indicated that the training provided through NDA positively impacted the nurses' knowledge and fulfilled their learning needs. Statistical analysis showed a significant difference between knowledge, practice, and confidence score changes for the two-time point period, i.e. before and after the training.
It can be concluded that conducting Continuing Nursing Education (CNE) through a digital learning program is an effective teaching-learning method in the nursing curriculum.
•A 3D ANCR spur gear developed and fracture behaviour is investigated.•Effect of important gear parameters on SIFs under mixed mode condition are explored.•Influence of individual fracture mode on ...effective SIF is determined.•The increase in module, number of teeth and addendum factor reduces the SIF.
As a high power transmission capacity and long durability constitute an essential requirement for mechanical machinery, the mechanical transmission gears need to be modified to improve the performance. The increasing drive side pressure angle is one of the methods for enhancing load-carrying capacity of the spur gear. The fracture characteristics of asymmetric gears need to be investigated to estimate the fatigue life. The location and magnitude of stress intensity factors mainly depend on gear tooth geometry, gear parameters, crack tip location, and applied force. Most of the literature study of fracture analysis carried out for the symmetric gears and the majority of them are two-dimensional analysis. In this study, a parametric analysis carried out for asymmetric spur gears to examine the fracture behaviour under mixed-mode fracture condition and explore the significance of each gear parameters. The maximum bending stress location for each gear pair is determined and the crack is introduced at that region. The stress intensity factor (SIF) for each mode is estimated and the effective stress intensity factor at each node along the face width is determined. In addition, the effect of opening mode, sliding mode and tearing mode on effective stress intensity factor for fillet crack is examined. This analysis inferred that the effect of opening mode fracture is predominant in the effective stress intensity factor irrespective of gear parameters.
Biofilm development on surfaces leads to biofouling, which is an undesirable phenomenon in the marine industry. Marine fouling leads to an increase in fuel consumption and corrosion of propeller ...blades. Most of the antifouling technologies available today are chemical methods that have detrimental effects on the environment. The current work focused on producing non-toxic and effective antifouling systems to control biofilm formation on the titanium alloy surfaces, which has potentially wide range of applications in the marine industry, such as propeller blades, the hull of the ships, heat exchangers, and offshore piping systems. A laser micro-machining was used in this study for the generation of surface texture patterns on the titanium specimens. The contact angle of the untextured surface was 28°, but the wettability of the textured surface increased with a contact angle of 134° for a square pit and 112° for a triangular pit. Surface roughness of the untextured sample showed Ra = 3.811 μm, but post-laser-texturing, the Ra value increased to 10.66 μm and 9.55 μm for the square pit pattern and triangular pit pattern, respectively. Microbes formed biofilm on the untextured specimen but, the square textured surface showed no apparent biofilm formation, while the biofilm was found in triangular textured surface as seen under the fluorescence and scanning electron microscope. The biofilm biomass was significantly reduced in the square textured surface. This work showed that laser textured surfaces might be potentially used to reduce biofilm development on the surfaces. Unlike most methods used for reducing bacterial adhesion, this kind of physical alteration of the surface topography is non-toxic, and it will help to prolong the life of the components used in the marine environment.
Physical alteration of the surface topography by the LASER over the surface of titanium alloy (Ti6Al4V) is non-toxic and will help to prolong the life of the specimen by making the surface hydrophobic and resists the bacterial growth. Display omitted
•Effect of laser surface textured pattern on microbial biofilm formation is analyzed in this work.•Surface texturing at the micro-level inhibits biofilm formation.•Size, shape, and hydrophobicity of the microtextures affect the bacterial adhesion.•Square pit pattern has shown higher contact angle and better biofilm inhibition.
In order to control the ferrite and austenite percentage in duplex stainless steel welding, many researchers try to change the laser welding parameters and cooling medium, but ignore to study the ...influence of heat sink effect on weld strength. In this work, the effect of aluminium heat sink and varying cooling medium on the laser welding of duplex stainless steel (DSS) 2205 is studied. The 2 mm thick DSS sheets welded with pulsed Nd: YAG laser welding machine by varying the cooling medium (air and oil) and an aluminium plate used as a heat sink. The welded specimens tested for tensile strength, micro-hardness, distortion, microstructure and radiography analysis. The faster cooling rate in the oil quenching process enhances the ferrite percentage compared with air-cooled samples. But the faster cooling rate in oil quenching leads to more distortion and using aluminium as a heat sink influenced positively the distortion to a small extent. The lower cooling rate in air quenching leads to a higher tensile strength of the welded specimen. The objective of this work is to analyse experimentally the effect of cooling medium and heat sink in the mechanical and metallurgical properties of laser welded duplex stainless steel.
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