Integral Quantity Data types Essay Example | Topics and Well Written Essays - 500 words

Integral Quantity Data types - Essay Example Yes, we can represent integers bigger than what int allows. Basically, integers have limit up to 2,147,483,647, and if we want to show number greater than this we have two options. We can use long or BigInteger. In this scenario, the limit for long is 9,223,372,036,854,775,807. For storing space and increasing the time of execution of program Java provides two data types (TutorialPoints, 2014; Oracle Corporation, 2014). Yes, for representing arbitrarily large integers we can use two other options: BigInteger and BigDecimal. However, it is not default because we write small programs in which our integer values can easily store and take less space. Hence, if BigDecimal or BigInteger becomes default it will require more space and the program execution will require additional time. Due to this reason there is not a single representation of integral quantities (TutorialPoints, 2014; Oracle Corporation,

Regulating Soldiers Body Temperature, Uniform Technology Summary Essay

Regulating Soldiers Body Temperature, Uniform Technology Summary - Essay Example A soldier may end up experiencing different health issues as a result of changes in climate in the areas they train and operate. These health issues can be divided into heat and cold based health issues. Heat related issues include heat cramps, syncope, fatigue and stroke and cold related health issues include hypothermia as well as frostbite. There are various technologies that can help monitor and change the body temperature of the soldiers with the changes in the climate. These technologies including phase change, hybrid, and evaporative as well as circulatory cooling technologies. Phase change material is a technology that can help in managing soldier’s body temperature if this technology is used to design the uniforms of the soldiers. This technology has several benefits including reduction of sweat, feeling of cold and decrease body temperature if the soldier is experiencing excessive warmth. While managing the temperature of a soldier’s body, this technology even provides soldiers with comfort. The technology is useful for soldier’s clothing because it does not causes issues when it comes in contract with the gears used by the soldiers. The technology lacks toxins; it is not flammable, is quite long lasting and can be reused. In order to use this technology along with uniforms the technology needs wires to function. This can restrict the acceptability of this technology, but if soldier’s uniforms have the ability to create electricity then this technology can easily be used. Another issue associated with this technology is fabric tearing but this problem may be experienced in the long run. Outlast is an existing clothing brand that has already developed uniforms for army professionals with the help of phase change material (PCM) (Armedforces-int.com 1). The company operates throughout the globe and is developing products that are made with PCM and these materials have been tested and approved by

Effect of Paclitaxel for Breast Cancer Treatment

Effect of Paclitaxel for Breast Cancer Treatment Effect of paclitaxel along with withnia sominiferia on lactate dehydrogenase enzyme activity changes in 7,12 di methyl benz(a) anthracene induced breast cancer wistar rats Dr.N.Muninathan1*, Dr.P. Mohanalakshmi2,Ambareesha Kondam k., Dr. S. Malliga3 1* – Department of Biochemistry, Meenakshi Medical College and Research Institute, Enathur, Kanchipuram – 631552, Tamil Nadu, India. 2- Department of Biochemistry, Sri Muthukumaran Medical College, Chennai 3- Department of Biochemistry, ESIC Medical College, Chennai Abstract Aim: The purpose of this study is to investigate the changes in the levels of lactate dehydogenase enzyme(LDH) activity and efficacy of combination of paclitaxel along with Withnia Sominiferia against breast cancer in experimental animals. Breast cancer is the commonest cancer among women in all developed countries (except Japan) as well as in North Africa, South America, and southeastern and western Asia. While the incidence of breast cancer appears to be increasing, mortality rates are now declining in at least some western countries. Breast cancer ranks third when both the sexes are considered together and is clearly a significant global public health problem. Design/Methods: Breast cancer was induced in rats by 7, 12 Di methyl benz(a) anthracene (DMBA) at the dosage of 20mgs dissolved in 0.5ml sunflower oil and administered into experimental animals for 28 weeks. In this study, we demonstrated that combination of paclitaxel and withania somnifera revert the changes in the rats f rom lethal dose of DMBA within 30 days. Results: All the isoenzymes LDH1 – LDH5 were observed in cancer bearing animals. Expression of these isoenzymes were found be reduced in paclitaxel and Withania somnifera treated animals. Conclusions: The treatment with combination of paclitaxel and withania somnifera effectively reduced LDH enzyme activity levels. So, from the obtained results it is concluded that paclitaxel and withania somnifera is capable of restoring the breast architecture. Key words: Withania somnifera, DMBA, Paclitaxel, LDH and Breast cancer. Introduction Breast cancer ranks third when both the sexes are considered together (Parkin, 1999) and is clearly a significant global public health problem. There are nearly 8,00,000 new cases of breast cancer worldwide each year .In approximately half of these patients, breast cancer will be the eventual cause of death. Incidence of breast cancer in Indian women is not as high as in western countries (Sinha et al., 2003) .It is the second most common cancer among women in south India. The age standardized rates vary from 22 to 28 per 1, 00,000 women (Sanghvi, 1998). Although the rates appear to be lower than those seen in developed countries, the burden of cancer in India is alarming. Worldwide incidences of breast cancer continue to rise and geographical variations in breast cancer incidence indicate that environment factors contribute to overall risk (Millikan, 1995). Exposure to environmental carcinogens early in life is thought to be one of the first events in the development of breast cancer. Each year breast cancer is diagnosed in 910,000 women worldwide and 376,000 women die from the disease. Most of these cases are in industrial countries e.g., North America (180,000) and Europe (220,000). PAH’s an important class of chemical carcinogens that are widespread in the ambient environment due to fossil fuel combustion for energy production, transportation and industry. DMBA, a potent PAH recognized as an initiator of both skin and liver cancer (Masaaki Miyata et al). The covalent binding of DMBA metabolites to DNA has been implicated as a critical step in the initiation phase of cancers. Paclitaxel (Taxol), a naturally occurring antineoplastic agent has shown great promise in the therapeutic management of certain human solid tumors particularly in metastatic breast cancer and malignancy involves skin, lung and refractory ovaries. It is the original member of the taxane group of anticancer drugs derived from the bark and needles of the pacific yew tree â€Å"Taxus brevifolia†. Paclitaxels antitumor activity was discovered in1960’s during a large scale 35,000 plants-screening program sponsored by the National Cancer Institute (NCI), USA. Withania is widely used in Ayurvedic medicine in India and in Unani and Middle Eastern traditional medicines, where it is highly regarded as a panacea, aphrodisiac, and rejuvenative. Withania sominifera (L). Dunal (Solanaceae) commonly called Ashwagandha (Sanskrit) is an Ayurvedic Indian medicinal plant, which has been widely used as a home remedy for several ailments.(Bhattacharya et al., 1997) The use of ashwagandha in Ayurvedic medicine extends back more than 3000 to 4000 years (Upton, 2000) (Agarwall et al., 1997). It has been widely extolled as a tonic, especially for emaciation in people of all ages, including babies, and enhances the reproductive function of both men and women. It has also been used for inflammation, especially in antitumor, arthritic and rheumatic conditions, for asthma, and as a major tonic to counteract aging and promote youthful longevity (Dhuley., 1998). Materials And Methods 1.1. Chemicals: 7,12 Dimethyl benz (a) anthracene and Withania somnifera were purchased from Sigma chemical company, USA. All the other chemicals used were of analytical grade. 1.2. Animal care and housing: Female Wistar rats, 6-8 weeks of age and weighing 150-200g, were used. The animals were procured from Central Animal House Block, Meenakshi Medical College and Research institute, Kanchipuran, Tamil Nadu, India and maintained in a controlled environmental condition of temperature and humidity on alternatively 12 h light/dark cycles. All animals were fed standard pellet diet (Gold Mohor rat feed, Ms.Hindustan Lever Ltd., Mumbai) and water ad libitum. This research work on wistar female rats was sanctioned and approved by the Institutional Animal Ethical Committee (REG NO. 765/03/ca/CPCSEA). 1.3. Experimental Design The animals were divided in to six groups of 6 animals each. Group I animals served as control, Group II, III, IV, V as animals treated with DMBA (20mg ) per animal in sunflower oil (0.5ml), three times a week for 28 weeks to induce skin cancer. After tumor induction Group III animals were treated with Paclitaxel (33mg/kg b.wt) once in a week for 4 weeks. Group IV animals were treated with Withania somnifera (250 µg/animal) for 30 days. Group V animals were treated with both Paclitaxel and Withania somnifera (as in group III and group IV). These were Group VI Control animals treated with paclitaxel and Withania somnifera for 28weeks plus 30 days. After the experimental period of 32 weeks, the animals were sacrificed by cervical decapitation. 1.4. Biochemical analysis The isoenzymes pattern of lactate dehydrogenase was separated by the method of Dietz and Lubrano (1967). III. Results Plate 1 depicts the Isoenzyme pattern of lactate dehydrogenase in serum of control and experimental animals. All the isoenzymes LDH1 – LDH5 were observed in cancer bearing (group II) animals. Expression of these isoenzymes were found be reduced in paclitaxel (group III) and Withania somnifera (group IV) treated animals. However a much significant reduction in the LDH isoenzyme expression pattern was observed in-group V animals treated with both paclitaxel and Withania somnifera. Lactate dehydrogenase (LDH) isoenzyme pattern in serum of control and experimental animals Lane 1:Control Lane 2:DMBA treated Lane 3:Paclitaxel treated Lane 4:Withania somnifera treated Lane 5:Paclitaxel and Withania somnifera treated cancer bearing animal Lane 6:Paclitaxel and Withania somnifera treated control animal IV. Discussion: Lactate dehydrogenase (LDH) is the most common clinical enzyme used in the cancer patients for prognostic purpose ( Invone et al., 1998). It has an important role in germ cell functions and can predict responses to chemotherapy and the prospects of remission. Human cancer tissues typically exhibit 2-3 fold increases in glycolytic enzymes and LDH activity. Sandhya Mishra et al. (2004) have also reported the increased level of LDH in breast cancer patients. Anderson and Kovatik (1981) reported greater LDH activity in breast cancer conditions. There was a significant increase in LDH level in serum of cancer bearing Group II animals. This might be due to the membrane disruptions that caused the release of these enzymes from the cancer cells or the overproduction by the tumor cells (Helmes et al., 1998). The elevated LDH activity may also have resulted from differences in the rate of synthesis, degradation or the excretion of the enzymes in the mammary cancer bearing animals. Schwartz (1973) has reported that among the isoenzymes LDH5 was six times greater than LDH1 in mammary tumor cells. Flavanoids have proved to possess antitumor effect on various animal models (Ames et al., 1995). The biological and pharmacological activity of Withania somnifera was associated with phenolic compounds mainly to flavanoids, aromatic acids and esters (Burdock, 1998; De catsro, 2001). Antioxidant activity of flavanoids may also be due to their structural features and its action on membrane (Saija et al., 1995; Mathur et al., 2003 ; Mohan et al., 2006). Paclitaxel being rich in flavanoid content possess antitumor and antiproliferative activities that stabilizes the membrane permeability and reduces the release of LDH. V. Statistical analysis For statistical analysis, one way analysis of analysis of Variance (ANOVA) was used, followed by the Newman-Keuls Multiple Comparison test. VI. Conclusion From the present study, the effect of Paclitaxel- Withania somnifera combination proved to be effective chemotherapeutic agent against DMBA induced Breast cancer in wistar rats compared to that of paclitaxel or Withania somnifera confirmed analyzing the LDH isoenzymes levels in serum. Reference Agarwal, R., Diwanay, S., Patki, P., and Patwardhan, B ( 1999). Studies on immunomodulatory activity of Withania somnifera (Ashwagandha) extracts in experimental immune inflammation. J Ethnopharmacol, 67: 27-35. Ames BN, Swirsky G and Willet WC. (1995). The causes and prevention of cancer. Proc.Natl.Acad.Sci.USA., 92:5258-5265. Anderson GR, Kovacik WP Jr. (1981). LDHK an unusual oxygen – sensitive lactate dehydrogenase expressed in human cancer. Proc. Natl. Acad. Sci. USA. 78 (8): 3209 – 13. Bhattacharya, S. K., Satyan, K. S., and Ghosal, S. (1997). Antioxidant activity of glycowithanolides from Withania somnifera. Indian J Exp Biol, 35: 236-239. Budhiraja, R. D., Sudhir, S., and Garg, K. N.( 1983). Cardiovascular effects of a withanolide from Withania coagulans, dunal fruits. Indian J Physiol Pharmacol, 27: 129-134. Burdock GA. (1998). Review of the biological properties and toxicity of bee propolis (propolis). Food and chemical toxicology. 36 : 347-363. Decastro SI. (2001). Propolis: biological and pharmacological activities. Therapeutic uses of this bee product. Annual review on biological sciences. 3 : 49-83. Dhuley, J. N. (1998). Therapeutic efficacy of Ashwagandha against experimental aspergillosis in mice. Immunopharmacol Immunotoxicol, 20: 191-198. Dietz AA. and Lubrano T. (1967). Separation and quantification of LDH isoenzyme by disc electrophoresis. Anal. Biochem., 20 : 246-257. Helmes MH, Modia A, Moneim EL, Moustafae MS, Bale EL and Safinoz MEL. (1998). Clinical values of serum LDH, ceruloplasmin and lipid bound sialic acid in monitoring patients with malignant lymphomas. Medical Science Research, 26 : 613-617. Iuvone, T., Esposito, G., Capasso, F., and Izzo, A. A. (2003). Induction of nitric oxide synthase expression by Withania somnifera in macrophages. Life Sci, 72: 1617- 1625. Mathur, R., Gupta, S. K., Singh, N., Mathur, S., Kochupillai, V., and Velpandian, T.( 2006). Evaluation of the effect of Withania somnifera root extracts on cell cycle and angiogenesis. J Ethnopharmacol, 105: 336-341. Millikan R, De Voto E, Newman B. and Savitz D. (1995). Studying environmental influences and breast cancer risk: suggestions for an integrated population based approach. Br.Cancer Res.Treat., 35: 79-89. Mohan, R., Hammers, H. J., Bargagna-Mohan, P., Zhan, X. H., Herbstritt, C. J., Ruiz, A., Zhang, L., Hanson, A. D., Conner, B. P., Rougas, J., and Pribluda, V. S.( 2004). Withaferin A is a potent inhibitor of angiogenesis. Angiogenesis, 7: 115-122. Parkin DM, Whelan SL, Ferlay, Raymond L, and Young J. (1997). Cancer incidence in five continents. Volume VIII.IARC. Scientific Publications, 143 IARC, Lyon, 858-1009. Rasool, M. and Varalakshmi, P.( 2003). Immunomodulatory role of Withania somnifera root powder on experimental induced inflammation: An in vivo and in vitro study. Vascul Pharmacol, 44: 406-410. Saija A, Scalese M, Lanza M, Marzullo D, Bonina F. and Castelli F. (1995). Flavanoids as antioxidant agents: Importance of their interactions with biomembranes. Free Rad.Biol.Med., 19: 481-486. Sandhya Mishra DC, Sharma and Praveen Sharma. (2004). Studies of Biochemical parameters in breast cancer with and without metastasis. Indian Journal of Clinical Biochemistry. 19(1) : 71 – 75. Sanghvi LD. (1998). Report on cancer epidemiology. Indian association of cancer research. 1-28. Schwartz MK. (1973). Enzymes in cancer (review ). Clin.Chem., 19: 10-22. Sinha R, Anderson DE, Mc Donald SS. and Greenwald P. (2003). Cancer risk and diet in India. 49(33) : 222-228.

Tension in Do Not Go Gentle Into That Good Night Essay -- Do Not Go G

Tension in Do Not Go Gentle Into That Good   Night  Ã‚   Dylan Thomas’s poem "Do Not Go Gentle Into That Good   Night", is an urgent plea from Thomas to his dying father, and all men not to give in to death.   Thomas uses himself as the speaker to the make the poem more personal.   The message of the poem is very inspirational.   Throughout the poem, Thomas uses different imagery and language to illustrate the tension between action and inaction.   The first stanza helps summarizes the meaning of the poem, urging old men to fight death.   In the first stanza of the poem Thomas uses assonance, †Old age should burn and rave at close of day; / Rage, rage against the dying of the light.† (2-3) The use of age in the second line, and rage twice in the third depict assonance.   Here Thomas is trying to disprove the notion that old age is a time to rest, and a time to look back with wishful regrets on one’s experiences. The middle four stanzas are examples of various types of men, their trials of life and the whisper of death upon them.   In ...

Inquiring Minds Want to Know Essay

Abstract This paper defines Penton Media’s sampling plan and research design for their study on if their reader service cards are still successful in getting buyer’s attentions. There are five questions that develop the sampling plan and Penton Media’s answers to these questions are described in this paper along with the strengths and weaknesses of their decisions. Their research design is also explained in the eight categories given. Finally, the strengths and weaknesses of their research design are given. Case Assignment 2 Penton Media has designed a research study to determine if the reader service cards are still a sustainable form of bringing in customers. Penton Media came up with a sampling plan in order answer this research plan. Their sampling plan answered five questions and has both strengths and weaknesses. They also formulated a research design, which includes eight categories of options to answer their research question. Their research design also includes strengths and weaknesses, and these will be further examined in this paper. Sampling Plan According to Cooper and Schindler (2014), the sampling plan includes five questions. These questions include (p. 344): What is the target population? What are the parameters of interest? What is the sampling frame? What is the appropriate sampling method? What size sample is needed? Once you have answered all these questions, you can determine the appropriate sampling design for your study. Penton Media has created their sampling plan from these questions. The target population for Penton Media’s study is the people who read their  business magazines. Their subscribers consist of 1.7 mission people in the US, so they originally tested out the survey via phone with a small selection of subscribers. They then sent out a second preliminary survey to 300 subscribers. From the first and second surveys, they construed a final survey and mailed it out to 4,000 of their business subscribers. From the total number of surveys sent out, they received 710 completed surveys. The parameters of interest in this study include the readers who are actually buyers for their company. Penton Media only chose to use the surveys from subscribers actually doing purchasing activities, so this would be considered a non-probability based sampling study. According to the case study presented by Cooper and Schindler (2014), â€Å"The survey sample was constructed using stratified disproportionate random sampling with subscribers considered as belonging to one of 42 cells (seven industry groups by six job titles)†. Strengths The strengths with Penton Media’s sampling plan include the parameters of interest and sampling frame. Their parameters of interest focus on the group of readers whose job is to buy for their company. Since this group of people directly match who they should be targeting, Penton Media is on the right track. Their sampling frame is also precise because it narrowed their list of people to send out the surveys to people working in the business fields as decision makers. Weaknesses The weakness of this study is the sample size. Penton Media chose to only send out 4,000 surveys when they actually have 1.7 million readers. This size seems small since only a little over 17% of the surveyor’s returned the survey. Sample size should be a representation of the whole, and .04% of the population isn’t a great representation. Research Design Several options are available to researchers when deciding with their research design will be. They include exploratory or formal studies, type of data gathering, extent of control, purpose, time frame, scope, environment, and perception. A researcher should ponder these options before designing their study. Penton Media was deliberate in their choices and based their answers to research design options on their research question. A formal study was designed to provide the answer to directly answer their research question. For data gathering, a communication study was used in the form of a survey. Ex post facto extent of control was used since Penton Media can’t change the results and have to report the results they receive. The purpose was chosen as a reporting study as they are compiling data and providing a summary of the survey results. This study’s time frame is cross-sectional with a survey being sent out once for the formal results. The topical scope is statistical because it wants to compare characteristics and draw conclusions. Field conditions were used in this study because there is no change in the surveyor’s environment. Finally, the participant’s perceptions are not changed and they are aware of the research being conducted. Strengths The strength of this study is in the ex post facto design where Penton Media has to report from the survey results. There is no way that Penton Media can change or modify the results so this makes the research more reliable and dependable. Another strength is that the participant’s environment and perceptions aren’t changed or affected. This makes for more honest and trustworthy results. Weaknesses A communication study is great for the research question that Penton Media is trying to answer. However, they could also get more data from their advertisers. Since many companies keep a record of how a customer finds out about their company, it would be worthwhile to also get statistics from them. This would complete the study and bring more results to complete the research question. Conclusion Penton Media has made some good decisions regarding their sampling plan and research design. They have answered the five questions to determine how they should set up their sample and made good decisions on target population, parameters of interest, sampling frame and method. However, they should have chosen a large sample size to represent the population.  Penton Media also made good choices in their research design. Their choice of a formal, communication, reporting, statistical study with ex post factor design, cross-sectional time frame, field conditions and unchanged perceptions are key to their success. Sampling plan and research design are key and Penton Media certainly made good decisions for their study. References Cooper, Donald R. and Schindler, Pamela S. Business Research Methods. New York: Irwin/McGraw-Hill, 2014. Print.

The Coexistence of Life and Death in Baraka, by Ron Fricke

The coexistence of life and death in Baraka, by Ron Fricke Why do people crowd a city and create problems for themselves? In 1992, Ron Fricke released the film Baraka, a film with no dialogue, and an inspiring soundtrack played over provocative scenes, typically comparing natural humans in their habitat to human damage and crowding. In two scenes, a big, dirty apartment complex is shown in contrast to a large, unclean cemetery, creating juxtaposition between the two. In the first scene, there are numerous buildings, showing that as the world population increases, conditions worsen as humans fight for space. The Kowloon walled city has a twisting series of stairways, alleys, and cat walks. These buildings, wrapped around an old military fort, are all at least 10 stories high, and dotted with clothes lines, water barrels and trash. The site was evicted and demolished in 1992. In the distance, a bustling city pays no attention to the stained, dirty concrete buildings, where 33,000 occupants face daily poverty in 250 square foot apartments. What is the result of such overcrowding? The industrial revolution of the 19th century showed us the answer. A substantial amount of residents lived around the factories, to shorten their commute. As population density increased, conditions soon became deplorable. To solve this problem, 19th century leaders introduced public transportation, which spread people out, and created a sustainable environment. In a following scene, the camera pans out to La Ciudad Blanca, Ecuador, an enormous grave yard, with multi level complexes of dirty white graves. Each grave has a personal adornment, from their loved ones. From candles to pictures, the decorations make every box look a little more humanized. It is strangely beautiful, with the messages and the grass growing through cracks in the pavement. This scene shows that as a world, when we get overcrowded, we must overcrowd other aspects of life. This really shows that death is a part of life as life is a part of death. These two juxtaposed scenes show how overcrowding is an issue and it’s hard to put a face on a statistic. The idea of putting a huge city and a huge cemetery together makes a point, that the present city solution has been adopted in cemeteries. The cycle of poverty comes into play, when so many are trapped in one place, with no room to improve; they end up in the same spot after life, and leave their children in the same rut. This idea was explored in Sandra Cisneros’s book, The House on Mango Street, where Esperanza realizes the only way out of the cycle is through hard work and higher education. The film Baraka teaches us many lessons, including the fact of overcrowding, and the harm it has caused, and will cause. In the walled city, thousands of people went without basic sanitation, and lived in 250 square feet or less, often working all day to provide for there families. When trapped in this cycle, you will end up in the same state of poverty as you were in during life. Hard work is the key of success and getting out of poverty.

Convicted Felon

Convicted Felon Convicted Felon Convicted Felon By Maeve Maddox A person who commits a felony is called a felon. A felony is a serious crime; what constitutes a felony differs from state to state, but in every state, crimes fall into three categories: infractions, misdemeanors, and felonies. 1. Infraction An infraction is a petty offense punishable by small fines. An infraction cannot result in a jail sentence, so the person accused of one is not entitled to a jury trial. In some states, a traffic violation is an infraction; in others, a traffic ticket may be a civil offense. 2. Misdemeanor A misdemeanor is a criminal offense that can be punished by up to a year in jail. Instead of receiving a jail sentence, offenders who commit a misdemeanor may be punished by the payment of a fine, restitution, probation, and/or community service. Defendants charged with a misdemeanor are entitled to a jury trial. In some states, selling cigarettes to a minor is a misdemeanor. 3. Felony A felony is the most serious category. A felony involves serious physical harm or threat of harm, for example, assault with a deadly weapon, forcing a person to participate in prostitution, attacking a family member, attacking a stranger, etc. Felonies are further classified according to the perceived level of seriousness: Class A Felonies, Class B Felonies, etc. Felons are often referred to in the media as â€Å"convicted felons†: Baltimore Convicted Felon Exiled to Over 9 Years in Prison Convicted felon bails on job Angry sheriff questions how convicted felon escaped again Convicted felon shoots dogs at Gulfport residence The AP Stylebook defines felon as â€Å"a person who has been convicted of a felony, regardless of whether the individual actually spends time in confinement or is given probation or a fine instead.† Once a person has been convicted of a felony, the person is a felon. As the AP points out, referring to a felon as â€Å"a convicted felon† is redundant. Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the Vocabulary category, check our popular posts, or choose a related post below:Creative Writing 101Try to vs. Try andSentence Adverbs