Interest in Rainwater Essay Example for Free

Interest in Rainwater Essay The article entitled â€Å"Interest in Rainwater Harvesting Grows in Colorado† written by Paul Day was about a proposal of Brad Lancaster, a rainwater virtuoso and initiator. His entire idea according to the news was that he wanted to use the rainwater for needs of the people and environment just like in Arizona and New Mexico. But the Executive Director of Colorado Waterwise, Paul Lander, prohibited his willingness to pursue this project because according to him it might result in breaking the rights of the people to that water. Lancaster insisted and he even showed two concrete project proposals for this. First, it would legalize the conception in countrysides that were not served by municipal water supplies. Lastly, it would instruct for conducting projects to study whether rainwater harvesting can be used without harming water rights. It interests me a lot because if we’re going to use the water from the sky in some ways, we can get lot of benefits out of it. I consider this as a biological issue because it discusses the precipitation process. This is very important because this is an exact example of learning how to utilize the nature for our advantage. The steps of scientific process: a. The usage of the rainwater purposefully though Colorado water law forbids it? b. Other places like Arizona and New Mexico can do it, why can’t we. c. They show the proposals using diagrams of storage tanks for collecting rainwater that runs off the rooftops home homes and businesses. d. The people who witness the presentation of the project agree that we can get a lot out of it. Scientific Terms: rainwater – water that comes form the sky project proposals – the entire flow or plan of the project and the things that they wanted to do precipitation process – the continuous cycle of water â€Å"Does Diabetes Make the Mind Go to Pieces† written by Mary Brophy Marcus is the second article. It imparted us about the risk of having Alzheimer’s disease and the effects of it are as follows: a. more prone to cognitive decline b. the mind’s ability to evaluate problems and the speed of processing information might suffer because of high rate of insulin or abnormal blood glucose. The experimentation by the researchers from the University of Alberta in Canada verified the people with diabetes and non diabetic were prone to mental decline according to the American Psychological Associations January issue of Neuropsychology but the executive function – complex, analytical thinking and speed processing were directed to the diabetic ones. In the journal Neuron published in December found out that if the brain didn’t get enough sugar it produced Alzheimer’s plaques but improving the brain’s blood flow might prevent or cured Alzheimer’s according to Robert Vassar, a professor of cell and molecular biology at Northwestern Universitys Feinberg School of Medicine and he recommended that doing some exercise, minimizing cholesterol intake and taking care of the hypertension could help a lot. On the contrary, according to Nir Barzilai, director of the Institute for Aging Research at Albert Einstein College of Medicine in New York that insulin worked in the nerves that went to the liver and it declared stoppage glucose production and healed diabetes but not in the blood. I found it fascinating because it conveyed awareness on how to take good care of our body. I considered this biological issue because it dealt with the health of an individual. The steps of the scientific process: a: Treating Alzheimer’s disease? b. the insulin is a great help c. they observe people with diabetes and non – diabetic individuals d. proper maintenance of insulin/glucose in our body and the habitual exercise and taking care of the body will prevent diseases. Scientific Terms: glucose – a crystalline sugar insulin – secreted by islets of Langerhans for carbohydrate’s metabolism and glucose regulation in the blood and produced diabetes mellitus when insufficient. Alzheimer’s disease progressive memory loss, impaired thinking, and changes in mood. The last article entitled â€Å"The Big Green Giveaway† by Tony Milney wanted to share about Mr. Miliband’s willingess to save the planet and our benefit out of it. The objective of putting up the household carbon emissions close to zero by 2050, the government decided to plan an environmental makeover. Establishing ground or air-source heat pumps, solar heating, solid wall insulation, or to join a community heating scheme are the suggested ways to lessen the average ? 300 a year of the wasted energy that needed an action or prevention. Based from the principles of this proposal, all the privileges were given to the homeowners to be able to fulfill the energy saving measures in our home. Not only this, but also the 90,000 solar water-heating systems in Britain. Another offer was the installation wind turbines, wood-pellet stoves, ground-source heat pumps and other eco kit by the Energy Saving Trust. And it even mentioned here the different gadgets used to save energy at home. This article caught my attention because it gave us information and ideas on how to save energy and at the same having advantage of it. I considered this as a biological issue because it discussed the environment that we had and the energy that we consumed. It is important because it helped the people saved energy without damaging the ecosystem. The steps of the scientific process: a. How can we avoid wasted energy? b. the misused of the energy and environment can cause this kind of problem c. they mentioned the different ways on how to save energy and the invented gadgets that could be of great help to the people d. there will be no wasted energy if the people would learn how to save energy wisely. Scientific Terms: energy dynamic exertion of power carbon a nonmetallic primarily tetravalent element found native gadgets an often small automatic or electronic device with a sensible use but often thought of as a novelty. Works Cited Day, Paul. â€Å"Interest in Rainwater Harvesting Grows in Colorado. † CBS4Denver. com (Feb 12, 2009): http://cbs4denver. com/local/Rainwater. Harvesting. illegal. 2. 934360. html Marcus, Mary Brophy. â€Å"Does Diabetes Make the Mind Go to Pieces? † USA TODAY (Jan. 28, 2009): http://www. usatoday. com/news/health/2009-01-28-diabetes-alzheimers_n. htm Milne, Tony â€Å"The Big Green Giveaway. † The Sunday Times (February 15, 2009): http://www. timesonline. co. uk/tol/news/environment/article5732920. ece

The roles of three different people at John Lewis in the Sales Department Essay Example for Free

The roles of three different people at John Lewis in the Sales Department Essay We asked the Caroline ODonovan the Human Resources Training Manager to tell us about three different jobs in the same department. Here is the information she gave us. John Lewis is run on certain Principles that all staff have to keep to: * By a clear understanding of what the employer expect of them and what there duties are. * commutate clearly and regularly to ovoid misunderstandings. * Know they rites and responsibilities within the business this is what they are entitled to and what they must take responsibility for. Purpose The Partnerships ultimate purpose is the happiness of all its members, through their worthwhile and satisfying employment in a successful business. Because the Partnership is owned in trust for its members, they share the responsibilities of ownership as well as its rewards profit, knowledge and power. Power Power in the Partnership is shared between three governing authorities, the Central Council, the Central Board and the Chairman. Profit The Partnership aims to make sufficient profit from its trading operations to sustain its commercial vitality, to finance its continued development and to distribute a share of those profits each year to its members, and to enable it to undertake other activities consistent with its ultimate purpose. Members The Partnership aims to employ people of ability and integrity who are committed to working together and to supporting its Principles. Relationships are based on mutual respect and courtesy, with as much equality between its members as differences of responsibility permit. The Partnership aims to recognise their individual contributions and reward them fairly. Job Descriptions These are the details of what an employee is expected to do at John Lewis. People are given a job description when they apply for a job so they know what they are applying for. At John Lewis the job descriptions include: * Job Title * Who they are responsible to * Status eg, Non-management * Main purpose * Job responsibilities John Lewis do not use person specifications. These state the personal qualities and qualifications that the applicants need to do the job. John Lewis say they discuss these things but do not give them out to staff as official documents. At John Lewis jobs are split into sales or non-sales jobs. In the selling department there are actually four different levels of jobs: 1. Assistant Sales Cashier 2. Sales Cashier 3. Section Manager 4. Selling Department Manager The three jobs we are looking at are Sales Cashier, Section Manager and Selling Department Manager. As the jobs get higher up the scale there are more responsibilities to that job. 1. Job title: Sales Cashier-sports equipment department Responsible to: Department Manager Status: Non-Management I have chosen the sports equipment store to do my project on. The job description( in italics) is what has been set for the staff and the meaning next to it(non italics): * Provide courteous and informed customer service and sell the merchandise by knowing the stock and relating it to customer needs. This means that the partners in that department will have to know all of the stock what product is best for a peculiar purpose and whats the best product for the customers. (Not meaning the most expensive product). If the member of staff is slightly unsure which is the best product then he/she will get another member who would Know. * To maintain the housekeeping standards of the department by keeping the fixtures and displays clean and well stocked with a balanced assortment. This means that the partners will have to keep a regular check on the stock and make sure when one is sold the same item is replaced on the shelf. Also to check equipment is not tampered with. * To complete monetary and credit transactions within procedure outlined in Instruction for the use of Cash Registers * To maintain the housekeeping standards of the department by keeping the fixtures and displays. clean and well stocked with a balanced assortmen.t * To assist with the preparation and execution of stocktaking * * To maintain security of cash, cash registers, sales checks and stock within the department. This is to have a partner always around the tills so that nothing will happen. Be aware of shoplifters. * To observe the Partnerships written rules and regulations particularly in relation to general behaviour to colleagues, customers and others, standards of dress, security, stock handling, discount, fire and emergency procedures. * To carry out duties required regularly or occasionally, according to the circumstances and guidance of the Department Manager. * Benefits: à ¯Ã‚ ¿Ã‚ ½5 à ¯Ã‚ ¿Ã‚ ½6 per hour depending on experience 2. Job title: Section Manager Responsible to Department Manager Main Purpose To assist in the management of the department by planning, organising and supervising the activities of the team; to ensure a high standard of service is maintained at all times. 1. Plan organise and supervise the activities of the team. (a) Plan and manage office floor cover. (b) Organise priorities and allocate tasks to match resources. (c) Review task completion against task allocation. (d) Coach on work performance to Partners. (e) Plan organise and supervise exceptional events as directed e.g. Stocktaking and Clearance. 2. Ensure Partners advise and sell to customers. (a) Monitor Partners selling skills. (b) Monitor Partners produce knowledge. (c) Encourage promotion of customer services. 3. Contribute to developing and maintaining customer service. (a) Develop and maintain positive relationships with customers. (b) Investigate and deal with customer complaints. (c) Control the procedure for dealing with complaints. (d) Maintain the Partnerships trading policy. (e) Identify, suggest and implement improvements to customer service. 4. Evaluate and monitor the receipt of payments from customers for goods and services. (a) Evaluate takings practices and procedures, (b) Monitor takings practices and processes at cash point. 5. Contribute to the continuous improvement of the department (a) Identify opportunities for solving problems and improving the department. (b) Recommend improvements for the department. Contribute to the implementation of improvements to the department. 6. Present and promote stock Maintain Partnerships display and merchandise standards. Organise, monitor and evaluate promotions of stock to increase sales. (c) Organise, monitor and evaluate the display of stock. 7. Maintain the availability of stock (a) Maintain stock availability. (b) Recommend measures to improve stock availability. (c) Monitor and assess stock levels against requirements. 8. Supervise the receipt and storage of goods (a) Supervise, organise and maintain stockholding areas. (b) Monitor and maintain stock movements. 9. Create, maintain and enhance productive working relationships (a) Create and enhance productive working relationships with your team and colleagues. (b) Maintain and enhance productive working relationships with your manager. (c) Identify and minimise conflict within your team. 10. Contribute to the training and development of your team. (a) Contribute to planning the training and development of your team. (b) Contribute to the training and development of your team. (c) Contribute to the assessment of training. (d) Take responsibility for your development. 11. Contribute to a secure safe and healthy workplace. (a) Implement procedures to maintain the security of cash and stock. (b) Monitor losses and investigate identified problems. (c) Assess and control risks to health and safety. (d) Implement procedures to deal with threats to security, health and safety. 12. Promote Partnership principles and practices. (a) Provide information to Partners on councils, committees and Partnership Social activities. (b) Maintain Partnership Rules and Regulations. (c) To assist with the preparation and execution of stocktaking. (d) To observe the Partnerships written rules and regulations particularly in relation to general behaviour to colleagues, customers, and others, standards of dress, security, stock handling, discount, fire and emergency procedures. (e) To carry out duties, required regularly or occasional, according to circumstances and guidance of Department Manager. 3. Job title: Selling Department Manager Responsible to : Head of Branch Main Purpose: To optimise sales, reputation and profitability of the department and branch through the management of resources and the development of Partners, ensuring we deliver quality customer service and exploit the opportunities presented by the merchandise. This is to be achieved within the spirit, policies and written regulations of the Partnership. 1. Maximise the sales performance of the department Use space and group merchandise effectively Offer the right stock Present stock to the best effect Ticket merchandise to aid customer selection Promote merchandise Maintain a clean and tidy, well stocked department Generate commercial awareness within the team 2. Contribute to the profitability of the selling department and branch by controlling wastage and costs Minimise known and unknown wastage Minimise costs to the department and branch 3. Maintain and improve customer service Evaluate performance against agreed standards of customer service Identify, agree and implement improvements to standards of customer service Manage and evaluate customer complaints and take steps to minimise them 4.Control the Stock Management System Monitor stock control information to ensure stock levels meet expected sales Establish and maintain the correct balance of stock assortment with buyers Evaluate the effectiveness of arrangements for receiving, marking off and distributing stock for the department Organise the stocktaking operation Monitor and control staffing resources within an agreed budget Plan and agree staff estimate and pay review Contribute to the selection of new recruits Monitor and control the department staff costs within estimate Encourage and maintain a learning and development culture for self, team and individuals to improve personal performance and achieve business objectives Take responsibility for own development and learning Develop section manager Develop the team Manage the development of individuals Support off the job learning opportunities to ensure Partners needs are identified and met Create, maintain and develop effective working relationships Establish and maintain trust and support of Parnters Establish and maintain positive relationship with branch and central management colleagues Identify and manage conflict Implement disciplinary and grievance procedures Provide support and guidance to deal with unacceptable performance Manage continuous improvement in the department Encourage Partners to contribute to the continuous improvement of the department. Visualise change Use stock control systems to develop our business Match stock to customer profiles Create administration systems to develop our business Raise Partners awareness of commercial developments Identify and manage proposals to improve the department Maintain the security, health and safety of the working environment Control and monitor all aspects of security for cash, stocks and Partners Organise, monitor and update Risk Assessment in the department Minimise risks to health and safety of Partners and customers Maintain and promote an interest in partnership principles and practices Encourage Partners to demonstrate a sense of responsibility as members of a democratically owned business Generate and sustain teams interest in, and knowledge of Partnership matters Maintain all Partnership Rules and Regulations and ensure individuals in team do likewise

Electronic Structure and Spontaneous Polarization in BiFeO3

Electronic Structure and Spontaneous Polarization in BiFeO3 Electronic structure and spontaneous polarization in multiferroic bulk BiFeO3 Z. Mahhouti 1,2,3,* , H. El Moussaoui 1 , M. Hamedoun 1 , M. El Marssi 3 , A. Lahmar 2 , A. El Kenz 2 , and A. Benyoussef 1,2,4 Abstract: The electronic structure, magnetic properties and spontaneous polarization in Bismuth ferrite BiFeO3 are investigated using first-principle calculations. The computed results show that the ground state of bulk BiFeO3 is rhombohedral R3c symmetry with G-type antiferromagnetic ordering and insulating, the computed results are in good agreement with available experiments. The electronic structure has been studied using the full potential linearized augmented plane wave (FP-LAPW) method within generalized gradient approximation (GGA) and modified Becke-Johnson potential (mBJ). Therefore, the finding band gap value is equal to the experimental value (Eg=2.5 eV) and much better than other theoretical values, the local magnetic moment at the Fe atoms reaches the experimental value and it is in good agreement with previously reported theoretical, with the large atomic displacement the modern theory of polarization predicts a large spontaneous polarization in multiferroic bulk BiFeO3. INTRODUCTION The multiferroic term denotes the coexistence of several ferroic orders (ferroelectric, ferromagnetic, and ferroelastic) in one material[1], coupled or not. Multiferroic materials are very rare because the origins of ferroelectricity and ferromagnetism are hardly compatible as shown by Hill et al.[2][3]. However, there are some exceptions such as La0.1Bi0.9MnO3 which is ferroelectric below 770 K and ferromagnetic below 105 K[4]. The definition of multiferroic has therefore been extended to materials with antiferroic orders such as BiFeO3 which is ferroelectric and antiferromagnetic.      Ã‚   Bismuth ferrite BiFeO3 (BFO) is one of the few magnetoelectric multiferroics who has simultaneously ferroelectric and antiferromagnetic orders under ambient conditions of temperature and pressure. Indeed, its high Curie temperature (TC = 1103 K)[5] and Nà ©el temperature (TN = 643 K)[6] provide a wide range of applications at different temperatures[7] such as spintronics, data storage and microelectronic devices[8][9], In addition, a magnetoelectric coupling is possible at room temperature. Recently, BFO has seen a considerable increase in interest since the discovery of a much better spontaneous polarization, greater than 150  µC/cm2, when the material is grown in thin layers[10]. This discovery aroused great enthusiasm among the scientific community who wanted to explain the origin of some phenomenon and explore this material again. The phase diagram established according to the reference[11] shows the succession of three phases with increasing of temperature denoted à ¯Ã‚ Ã‚ ¡, à ¯Ã‚ Ã‚ ¢,and à ¯Ã‚ Ã‚ §, respectively. In its bulk form and at room temperature, BFO has a distorted perovskite structure with rhombohedral symmetry and space group R3c (a = b = c = 5.63 Ã…, à ¯Ã‚ Ã‚ ¡ = 59.4 °)[12][8]. The primitive unit cell contains two formula units (ten atoms), each Fe atom is surrounded by six antiparallel spin neighbors, the magnetic moments are oriented perpendicularly to the [111] direction, which leads to develop a G-type antiferromagnetic order on the whole of the material. However, new observations have revealed that the direction in which antiferromagnetism manifests rotates through the crystal[13]. This noncollinearity propagates within the material with a period from 620 Ã… to 640 Ã…[13][14] and superimposes on the G-type antiferromagnetic order. As the noncollinearity is quite minimal , the simplification to a collinear magnetic structure is possible[15]. In this paper, the noncollinearity effects were not taken during our calculations. Since BFO is grown as a thin layers, the material may undergo a compressive or extensive stress due to the difference between the primitive cell of the material in its bulk form and those of the monocrystalline substrate, the small grown thickness is able to accept any relaxation of the structure. This can cause changes in the structure parameters of the crystal compared to its bulk form. However, other experimental works[16][17] showed that even BFO grown in thin layers, retains its rhombohedral symmetry. For a long time BFO considered too low to be exploitable ( Ps = 6.1  µC/cm2 ) according to the first measurements of Teague et al.[5], the ferroelectricity of BFO was studied again following the results of Young et al.[10] on thin layers of BFO ( Ps = 158  µC/cm2). However, many experimental studies carried out during this period gave a confusing results, the spontaneous polarization varying from 2.2  µC/cm2 [18] to 158  µC/cm2 [10]. The study of the ferroelectricity of BFO is a concrete example to combine experimental results and theoretical calculations. In this case, the calculation methods allow to explain the difference between the first measured values of bulk BFO and those obtained on the same material grown in thin layers. In this paper, we study in detail the magnetic properties of bulk BFO, while considering a G-type antiferromagnetic order. But it is necessary to determine first the electronic configuration and to calculate the band gap, in order to understand and obtain the theoretical model which corresponds to the reality of the material, and then to determine the spontaneous polarization using modern theory of polarization. METHOD The calculations which we present in the remainder of this paper use the density functional theory (DFT) implemented in WIEN2k code. The interactions between electrons and ions are described in the framework of full potential linearized augmented plane wave (FP-LAPW) method. As the 3d electrons in transition -metal Fe atom are incompletely filled, the spin density approximation was employed withinstry the Perdew-Burke-Ernzerhof (PBE) form of the generalized gradient approximation (GGA) and modified Becke-Johnson potential (mBJ). The new version of the exchange potential, proposed for the first time by the Becke and Johnson[19], was recently published by Tran and Blaha[20]. The modified Becke-Johnson potential (mBJ) proposed by Tran and Blaha is: With is the electronic density, is kinetic energy density and is the potential of Becke-Roussel. In this work, the mBJ potential is used in combination with the GGA-PBE approximation to compute the electronic structure, magnetic properties and spontaneous polarization in multiferroic bulk BFO. Our calculations do not include the spin-orbit interactions and the noncollinearity effects. The mesh of the first Brillouin zone in the reciprocal space was carried out using a 4 x 4 x 4 Monkhorst-Pack k-points grid. The structural parameters of BFO in space group R3c ( i.e, the lattice constant and atomic positions ) are considered as calculated by Wang et al.[8] as given from Kubel et al.[12]. The results of relaxing the cell volume, rhombohedral angle, and atomic positions within the R3c symmetry in reference[8] show that there is an alternation of Bi3+ and Fe3+ ions along the [111] axis; Each of these atoms is surrounded by six oxygen atoms, which thus form an octahedron around each cat ion. Inside the octahedron FeO6, the Fe3+ ion is outside the FeO2 plane (forming the base of the octahedron), which leads a distortion of the octahedron. The calculation of the spontaneous polarization using the modern theory of polarization is carried out by determining the difference in polarization between two symmetry (The non-centrosymmetric phase R3c which is ferroelectric and the centrosymmetric phase R-3c supposed paraelectric). In order to evaluate the polarization of the structure studied, we must therefore use a structure (centrosymmetric) as a reference with the same unit cell as the real structure (non-centrosymmetric), but its atomic positions do not induce electrical dipoles. Energetically, these two structures are very close, which confirms our choice of R-3c symmetry as a centrosymmetric reference. They differ by the addition of a center of inversion within the symmetry, and the passage from one symmetry to the other is due to the displacement of the atoms along the [111] direction which is accompanied with a rotation of the FeO6 octahedra perpendicular to the same direction. This evolution of the paraelectric phase t o the ferroelectric phase allows us to explain the birth of ferroelectricity within the bismuth ferrite BFO and to reproduce it efficiently in our calculations. The modern theory of polarization was applied for the first time to compute the ferroelectricity within the cubic perovskite-type KNbO3. The results obtained ( à ¯Ã‚ Ã¢â‚¬Å¾P = 35  µC/cm2 [21][22]) showed excellent agreement with the experimental data ( à ¯Ã‚ Ã¢â‚¬Å¾P = 37  µC/cm2[23]). Other studies were carried out subsequently, confirming the reliability of this method with respect to the experimental reality. Today, the modern theory of polarization is widely used. Results and Discussion Electronic and magnetic properties In this section, we study the electronic structure of bulk BFO in ferroelectric R3c structure, considering the relaxing values of cell parameter, rhombohedral angle and atomic positions by Wang et al.[8]. We computed and plotted the band structure and electronic state densities with the same parameters mentioned at the paragraph II. The band gap value are calculated using mBJ potential in combination with the GGA-PBE approximation, our calculated band gap value is the same as the value measured by Gao et al.[24] from the UV-visible diffuse reflectance spectrum witch is equal to 2.5 eV, our computed band gap is much better than other theoretical works such as Neaton et al.[15] who found an indirect band gap of 0.4, 1.3, and 1.9 eV using LSDA+U approximation with U=0, 2, and 4 eV, respectively. The same for Tà ¼tà ¼ncà ¼ et al.[25] they found an indirect band gap of 0.9, 1.4, and 2.1 eV using LSDA+U approximation with U=0, 2, and 4 eV, respectively. Our band structure results (Fig.1 ) indicate an indirect band gap of approximately 2.5 eV witch is in excellent agreement to the experimental measurement of about 2.5 eV [24][26]. Therefore, this equality between our calculated band gap and the experimental value confirms the insulating character of bulk BFO. In order to understand why the magnetic moments of the Fe atoms were arranged antiparallel within bulk BFO, we relaxed it according to different magnetic configurations: paramagnetic, ferromagnetic, and antiferromagnetic. The ground-state energy of the various possible magnetic configurations shows that the G-type antiferromagnetic configuration is the one which offers the material its greatest stability. FIG. 1. Calculated band structure for rhombohedral BiFeO3. FIG. 2. Calculated total density of states for rhombohedral BiFeO3. Calculated density of state (Fig.2) for R3c BFO indicates an identical distribution between electronic states up and down, which clearly exhibits the antiferromagnetic order of the material, in this case the antiferromagnetic order can only be G-type. The Fe atoms along the [111] axis have a local magnetic moment of 4.02 ÃŽÂ ¼B comes from 3d states, this value is much better than 4.25 ÃŽÂ ¼B and 4.17 ÃŽÂ ¼B reported by Tà ¼tà ¼ncà ¼ et al.[25] using LSDA+U with U = 4 and 6 eV, respectively. Therefore, our computed local magnetic moment of Fe atoms is very close to the measurement value of about 3.75ÃŽÂ ¼B [27]. FIG. 3. Atomic projection of electronic PDOS for rhombohedral BiFeO3. Figure 3 shows atomic projected electronic density of states (PDOS) around the ban gap region for both spin channels. The results suggest that the valence band are predominantly formed by Fe 3d states, hybridized with a contribution from O 2p states. Conduction band states are occupied by a large amount of Fe 3d states, hybridized with a small contribution of Bi 6p states that also contains a significant amount of O 2p states. Spontaneous polarization The spontaneous polarization was calculated within bulk BFO using the ferroelectric structure R3c and the hypothetical centrosymmetric phase R-3c. The centrosymmetric phase must be judiciously chosen, in order to found the difference of ferroelectric polarization between the centrosymmetric and non-centrosymmetric phases less than the quantum of polarization, Where is the electronic charge, is a lattice vector in the direction of polarization, and is the volume of the unit cell. Our calculations have shown that centrosymmetric phase R-3c is the structure closest to the ferroelectric structure R3c, both energetically as well as structural. This symmetry differs from the R3c only by the addition of a center of inversion. The transition from the paraelectric to the ferroelectric phase was characterized by a large displacement of the atoms along the [111] axis and a rotation of the FeO6 octahedra. Therefore, we expect that the spontaneous polarization develops along the [111] axis. In order to calculate the difference of polarization, we have considered that the transition from paraelectric to ferroelectric phase was done adiabatically and continuously. In this way, each atom moves along a path divided into segments of equal length. This method allowed us to follow the evolution of the spontaneous polarization during the whole paraelectric-ferroelectric transition. Throughout the paraelectric-ferroelectric transition, it is imperative to avoid any external contribution to symmetry, such as compression or expansion of the unit cell (in this case we do not calculate the real spontaneous polarization). For this reason, the structures used for our calculations have the same cell parameters, only the atomic positions were shifted. The modern theory of polarization compute the both, ionic and electronic contribution to the spontaneous polarization using the sum of the Wannier centers of the occupied bands. Our results showed that the spontaneous polarization developed along three directions, and was 58.8  µC/cm2 along each axis, resulting a spontaneous polarization of 101.1  µC/cm2 along the [111] axis which is in full agreement with the spontaneous polarization calculated by Neaton et al.[15] using LSDA+U. Early measurements on bulk BFO single crystals[5] found a small polarization of about 6.1  µC/cm2. On the other hand, many experiment studies on thin film samples of BFO showed a large spontaneous polarization of about 100-158  µC/cm2 [16][10]. The anomalously early value was caused by several explanations. First, the authors[5] indicated that their hysteresis loops were not saturated. Second, maybe the small value limited by the poor of the sample quality. Finally, the third explanation is that the crystal structure is not the same. Recently, Lebeugle et al.[28] have prepared a highly pure BFO single crystal (bulk BFO with a rhombohedral R3c symmetry) and measured the spontaneous polarization, they found a very large value of about 100  µC/cm2 [28] which is an intrinsic property of the bulk BFO, as expected by our theoretical studies. CONCLUSIONS In summary, Bismuth ferrite BiFeO3 is one of a few magnetoelectric multiferroics who has simultaneously ferroelectric and ferromagnetic orders, it has seen a considerable increase in interest since the discovery of a high spontaneous polarization. The first principle calculations with our approximations and parameters chosen allowed us to understand and obtain the behaviors of electronic and magnetic properties which make possible the computing of the right band gap and local magnetic moment. The property intrinsic of the large spontaneous electric polarization in bulk BiFe2O3 showed by recently experiment studies was confirmed by our theoretical investigations using the modern theory of polarization. These good agreements between our theoretical investigation and experimental measurement allow the scientific community to compute other properties and understand the physics behind the measurement at the atomic level. References [1]H. Schmid, Multi-ferroic magnetoelectrics, Ferroelectrics, vol. 162, no. 1, pp. 317-338, Jan. 1994. [2]N. A. Hill, Why Are There so Few Magnetic Ferroelectrics?, J. Phys. Chem. B, vol. 104, no. 29, pp. 6694-6709, Jul. 2000. [3]N. A. Hill, Density Functional Studies of Multiferroic Magnetoelectrics, Annu. Rev. Mater. Res., vol. 32, no. 1, pp. 1-37, Aug. 2002. [4]A. Moreira dos Santos et al., Orbital ordering as the determinant for ferromagnetism in biferroic BiMnO 3, Phys. Rev. B, vol. 66, no. 6, Aug. 2002. [5]J. R. Teague, R. Gerson, and W. J. James, Dielectric hysteresis in single crystal BiFeO3, Solid State Commun., vol. 8, no. 13, pp. 1073-1074, 1970. [6]G. A. Smolenskii and I. E. Chupis, Ferroelectromagnets, Phys.-Uspekhi, vol. 25, no. 7, pp. 475-493, Jul. 1982. [7]M. Fiebig, Revival of the magnetoelectric effect, J. Phys. Appl. Phys., vol. 38, no. 8, pp. R123-R152, Apr. 2005. [8]J. Wang, Epitaxial BiFeO3 Multiferroic Thin Film Heterostructures, Science, vol. 299, no. 5613, pp. 1719-1722, Mar. 2003. [9]Y. Tokura, MATERIALS SCIENCE: Multiferroics as Quantum Electromagnets, Science, vol. 312, no. 5779, pp. 1481-1482, Jun. 2006. [10]K. Y. Yun, D. Ricinschi, T. Kanashima, M. Noda, and M. Okuyama, Giant ferroelectric polarization beyond 150 ÃŽÂ ¼C/cm2 in BiFeO3 thin film, Jpn. J. Appl. Phys., vol. 43, no. 5A, p. L647, 2004. [11]R. Palai et al., ÃŽÂ ² phase and ÃŽÂ ³ ˆ’ ÃŽÂ ² metal-insulator transition in multiferroic Bi Fe O 3, Phys. Rev. B, vol. 77, no. 1, Jan. 2008. [12]F. Kubel and H. Schmid, Structure of a ferroelectric and ferroelastic monodomain crystal of the perovskite BiFeO3, Acta Crystallogr. B, vol. 46, no. 6, pp. 698-702, Dec. 1990. [13]I. Sosnowska, T. P. Neumaier, and E. Steichele, Spiral magnetic ordering in bismuth ferrite, J. Phys. C Solid State Phys., vol. 15, no. 23, p. 4835, 1982. [14]D. Lebeugle, D. Colson, A. Forget, M. Viret, A. M. Bataille, and A. Gukasov, Electric-Field-Induced Spin Flop in BiFeO 3 Single Crystals at Room Temperature, Phys. Rev. Lett., vol. 100, no. 22, Jun. 2008. [15]J. B. Neaton, C. Ederer, U. V. Waghmare, N. A. Spaldin, and K. M. Rabe, First-principles study of spontaneous polarization in multiferroic Bi Fe O 3, Phys. Rev. B, vol. 71, no. 1, Jan. 2005. [16]J. Li et al., Dramatically enhanced polarization in (001), (101), and (111) BiFeO3 thin films due to epitiaxial-induced transitions, Appl. Phys. Lett., vol. 84, no. 25, pp. 5261-5263, Jun. 2004. [17]G. Xu, H. Hiraka, G. Shirane, J. Li, J. Wang, and D. Viehland, Low symmetry phase in (001) BiFeO3 epitaxial constrained thin films, Appl. Phys. Lett., vol. 86, no. 18, p. 182905, May 2005. [18]V. R. Palkar, J. John, and R. Pinto, Observation of saturated polarization and dielectric anomaly in magnetoelectric BiFeO3 thin films, Appl. Phys. Lett., vol. 80, no. 9, pp. 1628-1630, Mar. 2002. [19]A. D. Becke and E. R. Johnson, A simple effective potential for exchange, J. Chem. Phys., vol. 124, no. 22, p. 221101, Jun. 2006. [20]F. Tran and P. Blaha, Accurate Band Gaps of Semiconductors and Insulators with a Semilocal Exchange-Correlation Potential, Phys. Rev. Lett., vol. 102, no. 22, Jun. 2009. [21]R. Resta, M. Posternak, and A. Baldereschi, Towards a quantum theory of polarization in ferroelectrics: The case of KNbO 3, Phys. Rev. Lett., vol. 70, no. 7, p. 1010, 1993. [22]R. Resta, M. Posternak, and A. Baldereschi, First-Principles Theory of Polarization in Ferroelectrics, in MRS Proceedings, 1992, vol. 291, p. 647. [23]W. Kleemann, F. J. 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Animal Testing Essay -- Animal Testing

Animal Testing As history shows man has endured and overcome many diseases and illnesses. These diseases killed many people and caused many to suffer. Most of these diseases have been cured do to mans medical research. Medical research has improved people’s lives along with increased life expectancy greatly. These medical breakthroughs have helped mankind in many ways, but in order to achieve these advances in medicine many animals suffered through testing. These test done to animals have improved the lives of many humans who would have suffered themselves. The testing of laboratory animals is an acceptable form of medical research. Today laboratory animal testing has come a long way and no longer are animals treated cruelly in testing, the welfare of the animals is a major concern. There are many concerns for animals’ safety in laboratory testing. The Research Defense Society says that the welfare of animals used in medical research is a major priority of the scientists, vets, and other professionals who perform these tests. This is for the good of the animals and not to mistreat them but also for accurate test results. â€Å"If an animal is suffering stress or pain it could affect the results of the research† (Animal Welfare) Animals are housed in the best possibly conditions in order to get reliable results from testing. The zoo community has demonstrated the feasibility and the benefits of maintaining animals in natural habitats. (Bayne) Along with healthy environments the animals used for testing are tested under the three R’s. The three R’s stand for Refinement, Reduction, and Replacement. These three principles are used to regulate the testing of laboratory animals by reducing the number of animals used, refine the ... ...erous advances in medicine and the many lives animal testing has saved proves that laboratory animal testing is a sound form of medical research. Through animal testing and research, human beings are expected to live longer, healthier, and stronger lives. Works Cited â€Å"Animal Testing.† U.S. Food and Drug Administration. http://vm.cfsan.fda.gov/~dms/cos-205.html. 10/1/2001 â€Å"Animal Research Facts.† http://www.fbresearch.org/micef.html. 10/10/2001 Bayne, Kathryn, and Roy Henrickson. Naturalistic Environment In captivity For Animal Behavior. Albany, New York. State University of New York Press, 1994 â€Å"The Three R’s of animal Testing Alternatives.† http://www.med.virginia.edu/hs-lirary/newsletter/1995/april/threer.html. 10/10/2001 â€Å"Animal Welfare and Regulation.† Research Defense Society. http://www.rds-online.org.uk/aboutrds/index.html. 9/25/2001

I Had to Fight to Read :: Personal Narrative, Autobiographical Essay

It was summer, stinking hot in a small town and I was fifteen and bored. The town librarian had been giving me grief since I was eleven and in the sixth grade, when she issued her first decree that I wasn't "old enough" to check out what became the first of a long line of books I had to fight to read. It was also the first of many times when one or both of my parents trudged down to the library to insist equally firmly that she had no right to restrict my choices as I had their permission to read whatever I wanted. The summer of my thirtieth year was especially difficult for this poor beleaguered woman. Her worst day came when I insisted on checking out all of Proust, every one of Thomas Wolfe's novels, and while I was at it, Joyce's Ulysses as well. After all, I reasoned, I had two weeks to keep these books and I was a fast reader. So I took them home, to the old iron glider under the grape arbor, and I propped myself up on a bunch of pillows and dug in with the same glee most people reserve for hot fudge sundaes. I fanned the pages and decided to read Look Homeward, Angel first because I like the way all those words leapfrogged over each other on every single page. Wow! The exuberant rush and gush of all those words! The torrent was overwhelming, the words blurred, I was losing the meaning. I knew I had to slow the pace somehow before I would have to admit that the librarian was probably right and perhaps I really wasn't "old enough" to make sense of it. And so I turned to Proust, finding relief within his exquisitely nuanced precision and pacing. My love of all things French was born with Proust, as I marveled at his privileged people and their luminous lives. Who were they really, I wondered, and was all of Paris like this, and if so, how soon could I get there? For the next two weeks, I cut back and forth between that unlikely duo, Wolfe and Proust, sweating from July's heat and the emotional impact of Brother Ben's death (best read when one is fifteen), then cooling off with the soothingly elegant rituals of Monsieur Swann and company.

Can Manufactured Bands Ever Be Classified As good Art? The Effect O :: essays research papers

Can Manufactured Bands Ever be Classified as 'Good' Art? The Effect of the Market on the Construction of Music Introduction Manufactured bands now make up a major percentage of chart music today, not least of them Take That, Boyzone, Bad Boys inc., East 17 and other all-boy pop bands. In this essay I would like to discuss how the standard of art has been lowered by the capitalistic system of the music industry, using a specific example - "Upside Down", which is maybe the latest addition to this genre of music. By this genre of music, I mean the all-boy bands which have been specifically manufactured and targeted at the 'teenybopper' age class (and also the gay market?). Personal Opinions To argue that this form of art is 'bad' art, one must have a reference point - a set of values by which to judge. This is almost always a personal opinion, and I would first of all like to explain my personal opinion. I believe that 'good' art has something to offer to the individual perceiver, be it painting, book, film, dance or music. These are all different forms of art, but one thing binds them all together - the fact that they are creations, created and crafted to the personal specifications of the artist. This makes the product original. Two values by which I judge music are creativity and originality. I believe that good art provides 'food for thought' - that special something which, after the tape has finished, after leaving the cinema or closing a book, leaves an 'aftertaste' - something to think about, be it, 'how did he/she play that' or, 'what was he/she trying to say with that piece,' the list goes on. Basic Market Analysis For the purposes of this essay, I want to split marketing into two general strategies. The first of these is where the designers make a "product" to their own specifications and then look to see where and how they will be able to sell it in the overall market. The second strategy is the opposite of the first - the designers examine the general market, target a certain area and tailor make a product to fit this area exactly. The latter of these strategies is the one employed when a band is going to be manufactured. The designers have studied the market and worked out what they think they can sell a certain group of consumers. Hirschman's 'three market segments' model (see figure 1) can be used to explain which type of bands fall into which category. The first segment is titled "Self-orientated Creativity.

India of My Dreams Essay

Long years ago, we made a tryst with destiny, and now the time comes when we shall redeem our pledge, not wholly or in full measure, but very substantially. At the stroke of the midnight hour, when the world sleeps, India will awake to life and freedom With these words of Pandit Nehru, on 15th August at the stroke of the midnight hour India declared itself independent from the British rule. As the Union Jack was being brought down and the Indian tricolor flew up the hopes and aspiration of the Indian founding fathers were completed. Sixty years after the birth of this massive and diverse nation though there has been considerable progress, the overall picture of life in the country is depressing. With increasing prices and growing unemployment, the common man remains as poor as he had been. Though education has spread, its standard and quality have received a set – back. Nor is the political scene very encouraging. While the working of democracy is not satisfactory, the forces of religion, provincialism and linguism pose a threat to the unity of the country. Our leaders lack the qualities of idealism, integrity and self – sacrifice, which were abundantly in evidence during the days of the struggle for freedom. In this bleak situation, it is natural for the youth of the country to have a vision of a stronger India. In the same way I have a vision too – a fearless, strong, self reliant India. I visualize my country way ahead of other nations all round the globe in every aspect, whether its development in any field or showing its military might or being a fore-runner in technological advancement, skills and prosperity. I visualize India being a country that will provide equality of opportunity to one and all irrespective of caste, creed, and sex. A place that will provide optimum scope for development of latent skills of an individual and then to use it for the welfare of the nation. I strive for such a country wherein the poorest of the poor feel that this is his country in building which his voice has its due importance. I wish for a constitution, which will release India from all thraldom and patronage, and give her, if needed, the right to sin. I dream of a nation where nobody is illiterate and nobody sleeps hungry, where there is no distinction on the basis of genre, religion or caste, where justice to a common man is neither denied or deleted, where corruption in public life does not exist, where criminals do not occupy ministerial berths nor enter legislative assemblies, where merit counts in every sphere of life, where jobs cannot be purchased, where criminals have to spend the rest of their lives behind the bars and where the intellectuals like Amartya Sen do not have to leave the country’s shore for higher research and recognition. Today India is grappling with divided states, poverty, and population on the one hand and a mà ©lange of languages, traditions, festivals, religions, cultures which poses a problem but my vision for India is a country where the Kirtans from Gurudwaras, and Azan from Mosques, the Bhajans from Temples and chiming of the bells from churches merge and mingle and produce a harmonious, melodious, tune of humanity. I dream of a casteless and a perfect India of which all Indians can be truly proud of. My vision of India may sound like a dreamer’s agenda but the day every Indian citizen realizes his responsibility towards his country my vision would be reality. At last I would like to conclude with the words of Sir Rabindranath Tagore: WHERE the mind is without fear and the head is held high Where knowledge is free Where the world has not been broken up into fragments By narrow domestic walls Where words come out from the depth of truth Where tireless striving stretches its arms towards perfection Where the mind is led forward by thee Into ever-widening thought and action Into that heaven of freedom, my Father, let my country awake.