. - sezgin, f., 2000, proclus arabus and the liber de causis ( buruklus ‘ inda l - ‘ arab wa - kitab al - idah fi l - khayr al - mahd ), frankfurt am main : institute for the history of arabic - islamic science at the johann wolfgang goethe university. - sheppard, a. d. r., 1980, studies on the 5th and 6th essays of proclus ' commentary on the republic, gottingen : vandenhoeck & ruprecht. - – – –, 1 982, “ proclus ' attitude to theurgy, ” corolla londiniensis, 32 : 212 – 224. - steel, c., 1978, the changing self. a study on the soul in later neoplatonism : iamblichus, damascius and priscianus, brussel : paleis der academien. - – – –, 1991, “ the one and the good : some reflections on a neoplatonic identification, ” in the neoplatonic tradition. jewish, christian and islamic themes, a. vanderjagt, and d. patzold ( eds. ), ( series : dialectica minora, 3 ), koln : dinter, pp. 9 – 25. - – – –, 1997, “ breathing thought. proclus on the innate knowledge of the soul, ” in the perennial tradition of neoplatonism, j. cleary ( ed. ), ( series : ancient and medieval philosophy, series 1, 24 ), leuven : leuven university press, pp. 293 – 309. - – – –, 1999, “ proclus on the existence of evil, ” and s. menn, “ commentary on steel, ” in proceedings of the boston area colloquium in ancient philosophy, vol. 14, j. j. cleary ( ed. ), leiden – new york – koln : brill, pp. 83 – 109. - – – –, 2001, “ the neoplatonic doctrine of eternity and time and its influence on medieval philosophy, ” in : the medieval concept of time. studies on the scholastic debate and its reception in early modern philosophy, p. porro ( ed. ), ( series : studien und texte zur geistesgeschichte des mittelalters, 75 ) leiden – new york – koln : brill


and its reception in early modern philosophy, p. porro ( ed. ), ( series : studien und texte zur geistesgeschichte des mittelalters, 75 ) leiden – new york – koln : brill, pp. 3 – 31. - – – –, 2002, “ neoplatonic versus stoic causality : the case of the sustaining cause ( ‘ sunektikon ’ ), ” in quaestio 2 : causality, c. esposito, and p. porro ( eds. ), ( series : yearbook of the history of metaphysics ), turnhout : brepols, pp. 77 – 93. - – – –, 2003, “ why should we prefer plato ' s timaeus to aristotle ' s physics? proclus ' critique of aristotle ' s causal explanation of the physical world, ” in ancient approaches to plato ' s timaeus, r. w. sharples, and a. sheppard ( eds. ), ( series : bulletin of the institute of classical studies. supplement, 78 ), london : institute of classical studies, pp. 175 – 187. - – – –, 2004, “ definitions and ideas, ” in proceedings of the boston area colloquium in ancient philosophy, vol. 19, j. j. cleary, and g. m. gurtler ( eds. ), leiden : brill, 103 – 121. - – – –, 2005a, “ theology as first philosophy. the neoplatonic concept of metaphysics, ” in quaestio 5. metaphysica, sapientia, scientia divina. soggetto e statuto della filosofia prima nel medioevo, atti del convegno della societa italiana per lo studio del pensiero medievale, bari, 9 – 12 giugno 2004, p. porro ( ed. ), brepols : turnhout, 3 – 21. - – – –, 2005b, “ proclus ' defence of the timaeus against aristotle ' s objections. a reconstruction of a lost polemical treatise, ” in plato ' s timaeus and the foundations of cosmology in late antiquity, the middle ages and renaissance, th. leinkauf, and c. steel ( eds. ), ( series : ancient and medieval philosophy, i 34 ), leuven : leuven university


and the foundations of cosmology in late antiquity, the middle ages and renaissance, th. leinkauf, and c. steel ( eds. ), ( series : ancient and medieval philosophy, i 34 ), leuven : leuven university press, pp. 163 – 193. - – – –, 2008, “ proclus on the mirror as metaphor of participation, ” in miroir et savoir. la transmission d ' un theme platonicien, des alexandrins a la philosophie arabo - musulmane, d. de smet, m. sebti, and g. de callatay ( eds. ), leuven : leuven university press, pp. 79 – 96. - – – –, 2010, “ proclus, ” in the cambridge history of late ancient philosophy, l. p. gerson ( ed. ), cambridge : cambridge university press [ forthcoming ]. - tarrant, h., and baltzly, d. ( eds. ), 2006, reading plato in antiquity, london : duckworth. - trouillard, j., 1982, la mystagogie de proclos, paris : les belles lettres. - van den berg, r. m., 2008, proclus ' commentary on the cratylus in context. ancient theories of language and naming, ( series : philosophia antiqua, 112 ), leiden – boston : brill. - van liefferinge, c., 1999, la theurgie : des ‘ oracles chaldaiques ’ a proclus, ( series : kernos. supplement, 9 ), liege : centre international d ' etude de la religion greque antique. - van riel, g., 2000, pleasure and the good life. plato, aristotle and the neoplatonists, ( series : philosophia antiqua, 85 ), leiden – new york – koln : brill. - watts, e. j., 2006, city and school in late antique athens and alexandria, ( series : the transformation of the classical heritage, 41 ), berkeley : university of california press. - westerink, l. g., j. trouillard, and a. p. segonds, 1990, prolegomenes a la philosophie de platon, ( series : collection des universites de france ), paris : les belles lettres


j. trouillard, and a. p. segonds, 1990, prolegomenes a la philosophie de platon, ( series : collection des universites de france ), paris : les belles lettres. - whittaker, j., 1975, “ the historical background of proclus ' doctrine of the authypostata, ” in de jamblique a proclus, h. dorrie, ( series : fondation hardt. entretiens tome, 21 ), geneve : vandœuvres, pp. 193 – 230 [ reprint in : studies in platonism and patristic thought, ( series : variorum reprints ), london : aldershot, 1984, xvi. how to cite this entry. preview the pdf version of this entry at the friends of the sep society. look up this entry topic at the indiana philosophy ontology project ( inpho ). enhanced bibliography for this entry at philpapers, with links to its database. - bibliography proclus – dwmc, university of leuven. - editions and translations proclus – dwmc, university of leuven. - repertoire des sources philosophiques antiques ( cnrs – paris ). - search on proclus at the open library. - w. j. hankey, french neoplatonism in the 20th century, in animus 4 ( 1999 ). the authors would like to thank radek chlup ( prague ), antonio luis costa vargas ( berlin ), and sabrina lange ( berlin ) for comments.


june 22, 1976. north atlantic. at 21 : 13 gmt a pale orange glow behind a bank of towering cumulus to the west was observed. two minutes later a white disc was observed while the glow from behind the cloud persisted. high probability that this may have been caused by interferometry using 3 - dimensional artificial scalar wave? fourier expansions? as the interferers. marine observer. 47 ( 256 ), apr. 1977. p. 66 - 68. " unidentified phenomenon, off barbados, west indies. " august 22, 1969. west indies. luminous area bearing 310 degrees grew in size and rose in altitude, then turned into an arch or crescent. high probability that this may have been caused by interferometry using artificial scalar wave? ( ( fourier expansions. ) ) marine observer. 40 ( 229 ), july, 1970. p. 107 - 108. " optical phenomenon : caribbean sea ; western north atlantic. " mar. 20, 1969. caribbean sea and western north atlantic. at 23 : 15 gmt, a semicircle of bright, milky - white light became visible in the western sky and rapidly expanded upward and outward during the next 10 minutes, dimming as it expanded. high probability that this may be caused by interferometry using artificial scalar wave? fourier expansions?. marine observer, 40 ( 227 ), jan. 1970. p. 17 ; p. 17 - 18. 7b. 21 - electricity 13. 06 - triple currents of electricity 14. 35 - teslas 3 6 and 9 ( ( 16. 04 - nikola nikola tesla describing what electricity is ) ) 16. 07 - electricity is a polar exchange 16. 10 - positive electricity 16. 16 - negative electricity - russell 16. 17 - negative electricity - tesla 16. 29 - triple currents of electricity ( ( figure 16. 04. 05 and figure 16. 04. 06 - nikola nikola tesla and lord kelvin ) ) part 16 - electricity and magnetism tesla - electricity from space what electricity is - bloomfield moore page last modified on wednesday 19 of may, 2010 05 : 23 : 05 mdt


thirds throughout the world. nowadays, in the advanced countries, the share is about 2. 5 percent - - eleven million people out of 430. 6 in the rest of the world, agricultural workers still account for almost half the labor force, with a world total of some 1. 3 billion workers ( 775 million in china and india alone ). such a massive transfer of labor, one of the key features of modern economic growth in the past two centuries, was made possible by a dramatic increase in product per worker. in short, agriculture is an outstanding success story. its achievements have been outshone by the even faster growth of industry and services, but the latter would have been almost impossible if the workers had not had sufficient food to eat. the aim of this book is to describe this success, and to understand its causes. chapter 2 illustrates the peculiarities of agriculture. its production depends on the environment : soil, climate, and the availability of water have always determined what peasants could grow, how much they had to work, and how much they could obtain from their efforts. these constraints have been relaxed in recent times, without totally disappearing. the factor endowment, and notably the amount of land per agricultural worker, determines the intensity of cultivation. the combined effects of the environment and the factor endowment have created long - lasting and area - specific patterns of land use, crop mix, and techniques ( " agricultural systems " ). the next three chapters present the main statistical evidence, loosely arranged in a production - function framework. chapter 3 deals with the long - term trends in output ( which has always been growing ), relative prices ( increasing in the first half of the nineteenth century, then roughly constant or slowly declining ), and world trade in agricultural products ( increasing quite fast before 1913 and again after 1950 ). the focus then shifts to the proximate causes of this growth, the increase in the use of factors ( chapter 4 ) and productivity growth ( chapter 5 ). historians have a fairly clear idea about the long - run change in factors. the total agricultural work force remained roughly constant all over the world, with the notable exception of western settlement countries ( north america, australia, argentina, and so on ) during settlement process - - that is, until the beginning of the twentieth century. the stock of capital grew fast beginning in the late nineteenth century, as machines substituted labor. although this conventional wisdom is not exactly wrong, it is, however, inspired a bit too much by the experience of the western world. the growth of land stock has been much


capital grew fast beginning in the late nineteenth century, as machines substituted labor. although this conventional wisdom is not exactly wrong, it is, however, inspired a bit too much by the experience of the western world. the growth of land stock has been much more geographically widespread and has lasted for longer than is commonly assumed. agricultural capital consists mainly of building, irrigation works, and the like, and thus it increased slowly but steadily throughout the period. the real process of mechanization started only in the 1950s, and the agricultural work force has gone on growing in absolute terms. thus, the growth of inputs ( extensive growth ) was the major cause of worldwide growth in agricultural production until the 1930s, but after world war ii, it slowed down. consequently, most of the big increase in total output in the past half - century has been achieved thanks to the growth in total factor productivity. the available estimates, surveyed in chapter 5, suggest that its growth has been increasing over time and that it has been faster in " advanced " countries than in ldcs. in the " advanced " countries, productivity growth has accounted for the whole of the increase in agricultural output. contrary to a common view, productivity growth has been faster in agriculture than in the rest of the economy, including manufacturing. chapter 6 focuses on the main source of this great achievement, technical progress. it starts by describing the main innovations, and then focuses on the process of their adoption. as in the rest of the economy, innovations are adopted when profitable, and profitability ultimately depends on the expected productivity gains and on factor endowment and factor prices. however, as the chapter argues, a standard neoclassical model cannot explain all the features of technical progress in agriculture. agricultural innovations depend on the environment and entail a high level of risk, and many of them yield little or no financial rewards to the inventor. these features call for a greater role of the state, both in the production and the diffusion of innovations. chapters 7, 8, and 9 deal with the institutional framework of agricultural production. " institutions " is a fairly vague word, which resists all attempts at a general definition. chapters 7 and 8 deal with property rights on labor and land, markets for goods and inputs ( labor, land, capital ), and agricultural co - operatives. chapter 7 is, to some extent, a general introduction to these issues and to the approaches of economists and historians to institutions. it discusses how institutions work and how they might affect the performance of agriculture. chapter 8 describes the main changes - - the creation of property rights


, to some extent, a general introduction to these issues and to the approaches of economists and historians to institutions. it discusses how institutions work and how they might affect the performance of agriculture. chapter 8 describes the main changes - - the creation of property rights on labor and land, the trends in the average size of farms, in landownership, and in contracts, and the development of markets for goods and factors. it also puts forward some tentative hypotheses on the likely causes of these changes and on their effects on agricultural performance - - although, it is fair to say, the discussion on these issues is surprisingly thin when compared to the attention they have received in the theoretical literature. chapter 9 focuses on the effects of agricultural policies. it argues that state intervention has only really affected agricultural development since the 1930s, and that, by and large, it has reduced the aggregate welfare of the whole population. the tenth, and last, chapter shifts the focus from agriculture to the whole economy. how did the growth of agricultural output and the change in input use affect modern economic growth? this issue has been the subject of much discussion in historical perspective, and it still looms large in the debates about the optimal development strategy for less developed countries. the chapter has no ambition to solve such a controversial issue. it sketches out the prevailing theories and deals very briefly with three case studies. the book closes with some very general remarks about the future of agriculture. the summary makes it clear that this is quite an ambitious book. it deals with many issues, and covers two centuries of agricultural history in the whole world, from monsoon asia to midwest prairies. any attempt to be comprehensive would be foolish. the potentially relevant literature spans dozens of languages, and many disciplines, from " traditional " agricultural economics and history to more " trendy " social and environmental history. just to quote an example, the fourth volume of a survey of agricultural economics literature, agriculture in economic development, contains more than two hundred pages of references. 7 assuming ( conservatively ) that there are twenty entries per page, the total sums up to almost four thousand entries. some of these works may be purely theoretical, and thus outside the scope of this book, but the majority should still be considered. the survey refers only to the less developed countries, deals ( almost ) exclusively with the post - world war ii period, lists only works in english, french, spanish, and portuguese published before 1990, and is probably, as with all surveys, not complete. a simple proportion suggests that there are thousands of potentially relevant


) exclusively with the post - world war ii period, lists only works in english, french, spanish, and portuguese published before 1990, and is probably, as with all surveys, not complete. a simple proportion suggests that there are thousands of potentially relevant references. clearly, no one in the world ( certainly not this author ) can reasonably claim to master all the literature. and even if this miracle were possible, it would be impossible to review it thoroughly and keep the book to a reasonable size. selective reading is an imperative. thus, i have decided to focus on more general contributions, and to favor works that frame their views in economic theory and buttress their statements with data. this approach has some clear and often rehearsed shortcomings. mainstream economic theory may appear too abstract to be relevant. agriculture is a highly local activity, and specialists in agrarian history always warn against broad generalizations, which, they claim, cannot capture the peculiarities of the area that they are dealing with. many data are missing, unreliable, or sometimes plainly wrong. reliable " historical " ( pre - 1950 ) data are available only for some " advanced " countries ( those of western europe, usa, japan, etc ). international organizations such as the un, fao, world bank, and the oecd have made a magnificent effort to extract comparable data for all countries from the information provided by national statistical offices, which are sometimes incomplete and / or of dubious quality. 8 however, there are some reasons for hope. modern development economics, with its emphasis on institutions, transaction costs, information, and so on, provides powerful tools for understanding rural societies, which can also be employed to explore societies of the past. economic historians have unearthed a great deal of new data, which, in spite of all their shortcomings, do throw light on many key issues. and, last but not least, i feel that there is no real alternative. a history of agriculture based on anecdotal evidence from local case studies would be a boundless and largely meaningless list of details. but details are sometimes fascinating and are useful for illustrating general points - - to put some flesh on the bare bones of quantitative analysis, so to speak. the reader may find the selection of these examples somewhat haphazard ( why - - for example - - discuss tenure in china during the 1930s instead of that in guatemala during the 1970s? ). it is, however, guided, whenever possible, by two principles : first, to deal with " large " countries ( china, india,


west lafayette, ind. - parts of the human brain think about the same word differently, at least when it comes to prepositions, according to new language research in stroke patients conducted by scientists at purdue university and the university of iowa. people who speak english often use the same prepositions, words such as " on, " " in, " " around " and " through, " to indicate time as well as location. for example, compare " i will meet you ' at ' the store, " to " i will meet you ' at ' 3 p. m. " these examples show how time may be thought of metaphorically in terms of space. just because it ' s the same word, however, doesn ' t mean the brain thinks about it the same way, said david kemmerer, an assistant professor of psychological sciences and linguistics at purdue ' s college of liberal arts. " there has been a lot of cognitive neuroscience research about how the brain processes language pertaining to concrete things, such as animals or tools, " said kemmerer, who also is an adjunct faculty member at the university of iowa ' s department of neurology, where this research was conducted. " this is the first cognitive neuroscience study to investigate brain regions for spatial and temporal relations - those involving time - used in language. " i was interested in whether these spatial or temporal prepositions can be dissociated in individuals with brain damage. one might think that if a person ' s knowledge of the word ' at ' to describe location is impaired, then his or her ability to use that same preposition to describe time would be disrupted. but we found the words implying time are processed independently. " this research was conducted at the benton neuropsychology laboratory in iowa ' s carver college of medicine and was funded by the purdue research foundation and the national institute for neurological disease and stroke. kemmerer ' s paper is available online at neuropsychologia. " this study has potential implications for neurology, " kemmerer said. " a clinician could use information about how brain injuries in stroke patients affect specific speech components to develop therapies to help their patients. " the four patients in kemmerer ' s study were used because of similar brain injuries, such as lesions from stroke, in the perisylvian region, which is responsible for language processing. kemmerer found the stroke subjects who passed the language tests asking about prepositions relevant to time subsequently failed when these same words reflected spatial


, such as lesions from stroke, in the perisylvian region, which is responsible for language processing. kemmerer found the stroke subjects who passed the language tests asking about prepositions relevant to time subsequently failed when these same words reflected spatial meanings. for example, the subjects were asked to choose the correct preposition for scenarios such as, " the baseball is ' on / in / against ' the glove. " two subjects did not select " in " as the correct answer. however, they did select " in " as the correct preposition for " it happened ' through / on / in ' 1859. " the other two subjects ' test performances were the opposite. kemmerer ' s earlier research with daniel tranel, professor of neurology at iowa ' s carver college of medicine, had confirmed that the left inferior prefrontal and left inferior parietal regions of the brain play a crucial role in processing spatial prepositions. the previous research with tranel was published in october ' s cognitive neuropsychology. this work, which has explored how different types of words are retrieved by different parts of the brain, is part of a larger - scale investigation being carried out by tranel and his colleagues at the university of iowa. " for example, we have identified the anterior left temporal lobe as being critical for proper nouns, whereas the left inferior prefrontal / premotor region is important for verbs, " tranel said. " the collaboration between myself, a neuropsychologist, and professor kemmerer, a neurolinguist, has yielded important breakthroughs in understanding how the brain operates language, due to the unique perspectives that these researchers bring to a common research agenda. " three of the patients in kemmerer ' s recent study also had damage to their brains ' left hemispheres, in an area known as the parietal lobe, which houses the supramarginal gyrus. this area is involved in spatial meaning, and it is the part of the brain that guides action. for example, the supramarginal gyrus coordinates how a person moves his or her hand toward a glass of water. previous research with normal brains identifies this area as important also in the knowledge and meaning of prepositions. the patients with damage to the supramarginal gyrus did not score high on the tasks that evaluated their knowledge of prepositions that dealt with space. in comparison, the fourth patient, who did not have similar damage to


##s. the patients with damage to the supramarginal gyrus did not score high on the tasks that evaluated their knowledge of prepositions that dealt with space. in comparison, the fourth patient, who did not have similar damage to this region of the brain, was able to demonstrate complete knowledge of spatial prepositions. kemmerer ' s next step will be looking at how the brain processes these prepositions in other languages. " if this is true in english, then what about the 6, 000 other known languages in the world? this time - and - space metaphor is used from language to language, but how the metaphor is used does vary, " he said. in english, months of the year are treated as containers. people say " in january " or " in february. " other languages treat months as surfaces. for example, " on january " or " on february. " despite the difference, there is a metaphor at work, kemmerer said. " the cross - linguistic ubiquity of the metaphor suggests that people are naturally inclined to conceptualize time in terms of space, " he said. " nevertheless, the neuropsychological data suggest that people don ' t need to invoke the metaphor every time they use prepositions to talk about time. just as the word ' breakfast ' doesn ' t require one to think of a morning meal in terms of breaking a fast, so the sentence ' she arrived at 1 : 30 ' doesn ' t require one to think of time as a series of points on a line. " source : eurekalert & otherslast reviewed : by john m. grohol, psy. d. on 21 feb 2009 published on psychcentral. com. all rights reserved. great things are not done by impulse, but by a series of small things brought together. - - vincent van gogh


/ vigorous intensity ( 12 miles of jogging per week ) or high amount / vigorous intensity ( 20 miles of jogging per week ). since the trial was designed solely to better understand the role of exercise, patients were told not to alter their diet during the course of the trial, which lasted six months for the group that did not exercise or eight - months for the exercise groups. the additional two months for the exercise group came at the beginning of trial, when participants slowly ramped up their exercise to their designated levels. the exercise was carried out on treadmills. for their analysis, the team compared two measurements of fitness – peak vo2 and time to exhaustion ( tte ) – before and after the trial. peak vo2 is a calculation that measures the maximum amount of oxygen that can be delivered by circulating blood to tissues in a given period of time while exercising. while all the exercise groups saw improvements in peak vo2 and tte after completing their exercise regimens, the researchers noticed some interesting trends. " we found that when we compared the low amount / moderate intensity group to the low amount / vigorous intensity group, we did not see a significant improvement in peak oxygen consumption, " duscha said. " however, when we increased the amount of exercise from 12 to 20 miles – at the same intensity – we did see an improvement in peak oxygen consumption. " also, although no statistically significant difference was detected between the low amount / moderate intensity group and the low amount / high intensity group, the researchers did see a trend toward both a separate and combined effect of exercise intensity and amount on increased peak vo2 levels. the duke team was led by cardiologist william kraus, m. d., who received a $ 4. 3 million grant from the national heart, lung and blood institute in 1998 to investigate the effects of exercise on sedentary overweight adults at risk for developing heart disease and / or diabetes. the results of that five - year trial, known as strride ( studies of targeted risk reduction interventions through defined exercise ), and other analyses of the data collected, began to be published in 2002. the duke team is currently enrolling patients in strride ii, in which researchers are seeking to determine the effects of weight training, alone and in combination with aerobic training, on cardiovascular health. joining duscha were duke colleagues cris slentz, ph. d., johanna johnson, daniel bensimhon, m. d., and kenneth knetzger. joseph houmard


yifu deng of qut ' s school of public health studied the interplay between genetics, smoking and the development of parkinson ' s disease with 400 people who had parkinson ' s disease and 400 people without it. dr deng looked at the genetic background of individuals in each group for the presence of the cyp2d6 gene, which had previously been suggested to metabolise the chemical compounds found in cigarette smoke, in both groups. he found that smokers with the gene who metabolised the cigarette smoke compounds quickly were less likely to be protected than those who metabolised the chemical compounds more slowly. " it seems that if the chemical compounds stay in the body longer they are more likely to have a preventative effect, " dr deng said. " it also seems that if you have the gene but you are not a smoker the gene may have no use in preventing parkinson ' s. " dr deng said it was not known how the cigarette smoke compounds protected against parkinson ' s. he warned that there were still many smokers who suffered from parkinson ' s. additionally, smoking was notorious for causing cancers. parkinson ' s disease is a common degenerative neurological disease in the elderly, affecting up to 4. 9 percent australians aged 55 and over. " our study findings aid in further understanding of the causes of parkinson ' s disease and may help identify people who are at higher risk of the disease, " he said. the study is the first to look at the genetic epidemiology of parkinson ' s disease by addressing individual genetic types in relation to cigarette smoke metabolism. dr deng ' s study may provide the potential to reveal new targets for strategies of altering parkinson ' s disease risk. media contact : niki widdowson, qut media officer, + 61 7 3864 1841 or firstname. lastname @ example. org. * * high res pic of dr deng available. last reviewed : by john m. grohol, psy. d. on 21 feb 2009 published on psychcentral. com. all rights reserved.


individual differences | methods | statistics | clinical | educational | industrial | professional items | world psychology | - main article : tomography computed tomography ( ct ), originally known as computed axial tomography ( cat or ct scan ) and body section roentgenography, ( and also known as computed axial tomography ( cat scan ) x - ray computed tomography is a medical imaging method employing tomography where digital geometry processing is used to generate a three - dimensional image of the internals of an object from a large series of two - dimensional x - ray images taken around a single axis of rotation. the word " tomography " is derived from the greek tomos ( slice ) and graphia ( describing ). ct produces a volume of data which can be manipulated, through a process known as windowing, in order to demonstrate various structures based on their ability to block the x - ray beam. although historically ( see below ) the images generated were in the axial or transverse plane ( orthogonal to the long axis of the body ), modern scanners allow this volume of data to be reformatted in various planes or even as volumetric ( 3d ) representations of structures. since its introduction in the 1970s, ct has become an important tool in medical imaging and neuroimaging to supplement x - rays and medical ultrasonography. although it is still quite expensive, it is the gold standard in the diagnosis of a large number of different disease entities. diagnosis of cerebrovascular accidents and intracranial hemorrhage is the most frequent reason for a " head ct " or " ct brain ". scanning is done with or without intravenous contrast agents. ct generally does not exclude infarct in the acute stage of a stroke, but is useful to exclude a bleed ( so anticoagulant medication can be commenced safely ). ct is also useful in the setting of trauma for evaluating facial and skull fractures. in the head / neck / mouth area, ct scanning is used for surgical planning for craniofacial and dentofacial deformities, evaluation of cysts and some tumors of the jaws / paranasal sinuses / nasal cavity / orbits, diagnosis of the causes of chronic sinusitis, and for planning of dental implant reconstruction. for evaluation of chronic interstitial processes ( emphysema, fibrosis, and so forth ), thin sections with high spatial frequency reconstructions are used. for evaluation of the mediastinum and hilar regions for lymphadenopathy


a sensitive method for diagnosis of abdominal diseases. it is used frequently to determine stage of cancer and to follow progress. it is also a useful test to investigate acute abdominal pain. renal / urinary stones, appendicitis, pancreatitis, diverticulitis, abdominal aortic aneurysm, and bowel obstruction are conditions that are readily diagnosed and assessed with ct. ct is also the first line for detecting solid organ injury after trauma. oral and / or rectal contrast may be used depending on the indications for the scan. a dilute ( 2 % w / v ) suspension of barium sulfate is most commonly used. the concentrated barium sulfate preparations used for fluoroscopy e. g. barium enema are too dense and cause severe artifacts on ct. iodinated contrast agents may be used if barium is contraindicated ( e. g. suspicion of bowel injury ). other agents may be required to optimize the imaging of specific organs : e. g. rectally administered gas ( air or carbon dioxide ) for a colon study, or oral water for a stomach study. ct has limited application in the evaluation of the pelvis. for the female pelvis in particular, ultrasound is the imaging modality of choice. nevertheless, it may be part of abdominal scanning ( e. g. for tumors ), and has uses in assessing fractures. ct is also used in osteoporosis studies and research along side dxa scanning. both ct and dxa can be used to asses bone mineral density ( bmd ) which is used to indicate bone strength, however ct results do not correlate exactly with dxa ( the gold standard of bmd measurment ). dxa is far more expensive, and subjects patients to much higher levels of ionizing radiation, so it is used infrequently. advantages and hazards edit advantages over projection radiography ( see radiography ) edit first, ct completely eliminates the superimposition of images of structures outside the area of interest. second, because of the inherent high - contrast resolution of ct, differences between tissues that differ in physical density by less than 1 % can be distinguished. third, data from a single ct imaging procedure consisting of either multiple contiguous or one helical scan can be viewed as images in the axial, coronal, or sagittal planes, depending on the diagnostic task. this is referred to as multiplanar reformatted imaging. radiation exposure edit


of this is increased with patients who have preexisting renal insufficiency, preexisting diabetes, or reduced intravascular volume. in general, if a patient has normal kidney function, then the risks of contrast nephropathy are negligable. patients with mild kidney impairment are usually advised to ensure full hydration for several hours before and after the injection. for moderate kidney failure, the use of iodinated contrast should be avoided ; this may mean using an alternative technique instead of ct e. g. mri. perhaps paradoxically, patients with severe renal failure requiring dialysis do not require special precautions, as their kidneys have so little function remaining that any further damage would not be noticable and the dialysis will remove the contrast agent. x - ray slice data is generated using an x - ray source that rotates around the object ; x - ray sensors are positioned on the opposite side of the circle from the x - ray source. many data scans are progressively taken as the object is gradually passed through the gantry. they are combined together by the mathematical procedure known as tomographic reconstruction. newer machines with faster computer systems and newer software strategies can process not only individual cross sections but continuously changing cross sections as the gantry, with the object to be imaged, is slowly and smoothly slid through the x - ray circle. these are called helical or spiral ct machines. their computer systems integrate the data of the moving individual slices to generate three dimensional volumetric information ( 3d - ct scan ), in turn viewable from multiple different perspectives on attached ct workstation monitors. in conventional ct machines, an x - ray tube and detector are physically rotated behind a circular shroud ( see the image above right ) ; in the electron beam tomography ( ebt ) the tube is far larger and higher power to support the high temporal resolution. the electron beam is deflected in a hollow funnel shaped vacuum chamber. xray is generated when the beam hits a stationary target. the detector is also stationary. the data stream representing the varying radiographic intensity sensed reaching the detectors on the opposite side of the circle during each sweep is then computer processed to calculate cross - sectional estimations of the radiographic density, expressed in hounsfield units. sweeps cover 360 or just over 180 degrees in conventional machines, 220 degrees in ebt. ct is used in medicine as a diagnostic tool and as a guide for interventional procedures. sometimes contrast materials such as intravenous iodinated contrast are used. this


360 or just over 180 degrees in conventional machines, 220 degrees in ebt. ct is used in medicine as a diagnostic tool and as a guide for interventional procedures. sometimes contrast materials such as intravenous iodinated contrast are used. this is useful to highlight structures such as blood vessels that otherwise would be difficult to delineate from their surroundings. using contrast material can also help to obtain functional information about tissues. pixels in an image obtained by ct scanning are displayed in terms of relative radiodensity. the pixel itself is displayed according to the mean attenuation of the tissue ( s ) that it corresponds to on a scale from - 1024 to + 3071 on the hounsfield scale. pixel is a two dimensional unit based on the matrix size and the field of view. when the ct slice thickness is also factored in, the unit is known as a voxel, which is a three dimensional unit. the phenomenon that one part of the detector can not differ between different tissues is called the partial volume effect. that means that a big amount of cartilage and a thin layer of compact bone can cause the same attenuation in a voxel as hyperdense cartilage alone. water has an attenuation of 0 hounsfield units ( hu ) while air is - 1000 hu, cancellous bone is typically + 400 hu, cranial bone can reach 2000 hu or more ( os temporale ) and can cause artefacts. the attenuation of metallic implants depends on atomic number of the element used : titanium usually has an amount of + 1000 hu, iron steel can completely extinguish the x - ray and is therefore responsible for well - known line - artefacts in computed tomogrammes. windowing is the process of using the calculated hounsfield units to make an image. the various radiodensity amplitudes are mapped to 256 shades of gray. these shades of gray can be distributed over a wide range of hu values to get an overview of structures that attenuate the beam to widely varying degrees. alternatively, these shades of gray can be distributed over a narrow range of hu values ( called a narrow window ) centered over the average hu value of a particular structure to be evaluated. in this way, subtle variations in the internal makeup of the structure can be discerned. this is a commonly used image processing technique known as contrast compression. for example, to evaluate the abdomen in order to find subtle masses in the liver, one might use liver windows. choosing 70 hu as an


of the structure can be discerned. this is a commonly used image processing technique known as contrast compression. for example, to evaluate the abdomen in order to find subtle masses in the liver, one might use liver windows. choosing 70 hu as an average hu value for liver, the shades of gray can be distributed over a narrow window or range. one could use 170 hu as the narrow window, with 85 hu above the 70 hu average value ; 85 hu below it. therefore the liver window would extend from - 15 hu to + 155 hu. all the shades of gray for the image would be distributed in this range of hounsfield values. any hu value below - 15 would be pure black, and any hu value above 155 hu would be pure white in this example. using this same logic, bone windows would use a wide window ( to evaluate everything from fat - containing medullary bone that contains the marrow, to the dense cortical bone ), and the center or level would be a value in the hundreds of hounsfield units. three dimensional ( 3d ) reconstructionedit because contemporary ct scanners offer isotropic, or near isotropic, resolution, display of images does not need to be restricted to the conventional axial images. instead, it is possible for a software program to build a volume by ' stacking ' the individual slices one on top of the other. the program may then display the volume in an alternative manner. this is the simplest method of reconstruction. a volume is built by stacking the axial slices. the software then cuts slices through the volume in a different plane ( usually orthogonal ). optionally, a special projection method ( maximum - intensity projection ( mip ) or minimum - intensity projection ( mip ) can be used to build the reconstructed slices. mpr is frequently used for examining the spine. axial images through the spine will only show one vertebral body at a time and cannot reliably show the intervertebral discs. by reformatting the volume, it becomes much easier to visualise the position of one vertebral body in relation to the others. modern software allows reconstruction in non - orthogonal ( oblique ) planes so that the optimal plane can be chosen to display an anatomical structure. this may be particularly useful for visualising the structure of the bronchi as these do not lie orthogonal to the direction of the scan. for vascular imaging, curved - plane reconstruction can be performed. this allows bends in a vessel to be ' straightened ' so that the


useful for visualising the structure of the bronchi as these do not lie orthogonal to the direction of the scan. for vascular imaging, curved - plane reconstruction can be performed. this allows bends in a vessel to be ' straightened ' so that the entire length can be visualised on one image, or a short series of images. once a vessel has been ' straightened ' in this way, quantitative measurements of length and cross sectional area can be made, so that surgery or interventional treatment can be planned. mip reconstructions enhance areas of high radiodensity, and so are useful for angiographic studies. mip reconstructions tend to enhance air spaces so are useful for assessing lung structure. 3d rendering techniquesedit surface rendering : a threshold value of radiodensity is chosen by the operator ( e. g. a level that corresponds to bone ). a threshold level is set, using edge detection image processing algorithms. from this, a 3 - dimensional model can be constructed and displayed on screen. multiple models can be constructed from various different thresholds, allowing different colors to represent each anatomical component such as bone, muscle, and cartilage. however, the interior structure of each element is not visible in this mode of operation. volume rendering : surface rendering is limited in that it will only display surfaces which meet a threshold density, and will only display the surface that is closest to the imaginary viewer. in volume rendering, transparency and colors are used to allow a better representation of the volume to be shown in a single image - e. g. the bones of the pelvis could be displayed as semi - transparent, so that even at an oblique angle, one part of the image does not conceal another. where different structures have similar radiodensity, it can become impossible to separate them simply by adjusting volume rendering parameters. the solution is called segmentation, a manual or automatic procedure that can remove the unwanted structures from the image. some slices of a cranial ct scan are shown below. the bones are whiter than the surrounding area. ( whiter means higher radiodensity. ) note the blood vessels ( arrowed ) showing brightly due to the injection of an iodine - based constrast agent. a volume rendering of this volume clearly shows the high density bones. after using a segmentation tool to remove the bone, the previously concealed vessels can now be demonstrated. the first commercially viable ct system was invented by godfrey newbold hounsfield in hayes, england at thorn emi central research laboratories using x - rays. houn


a pencil - thin beam of radiation directed at one or two detectors. the images were acquired by a " translate - rotate " method in which the x - ray source and the detector in a fixed relative position move across the patient followed by a rotation of the x - ray source / detector combination ( gantry ) by one degree. in the emi - scanner, a pair of images was acquired in about 4 minutes with the gantry rotating a total of 180 degrees. three detectors were used ( one of these being an x - ray source reference ), each detector comprising a sodium iodide scintillator and a photomultiplier tube. some patients had unpleasant experiences within these early scanners, due to the loud sounds and vibrations from the equipment. - second generation : this design increased the number of detectors and changed the shape of the radiation beam. the x - ray source changed from the pencil - thin beam to a fan shaped beam. the " translate - rotate " method was still used but there was a significant decrease in scanning time. rotation was increased from one degree to thirty degrees. - third generation : ct scanners made a dramatic change in the speed at which images could be obtained. in the third generation a fan shaped beam of x - rays is directed to an array of detectors that are fixed in position relative to the x - ray source. this eliminated the time consuming translation stage allowing scan time to be reduced, initially, to 10 seconds per slice. this advance dramatically improved the practicality of ct. scan times became short enough to image the lungs or the abdomen ; previous generations had been limited to the head, or to limbs. patients have reported more pleasant experiences with the third and fourth generation ct scanners because of greatly reduced noise and vibration compared to earlier models. - fourth generation : this design was introduced, roughly simultaneously with 3rd generation, and gave approximately equal performance. instead of a row of detectors which moved with the x - ray source, 4th generation scanners used a stationary 360 degree ring of detectors. the fan shaped x - ray beam rotated around the patient directed at detectors in a non - fixed relationship. bulky, expensive and fragile photomultiplier tubes gradually gave way to improved detectors. a xenon gas ionization chamber detector array was developed for third generation scanners, which provided greater resolution and sensitivity. eventually, both of these technologies were replaced with solid - state detectors : rectangular, solid - state photodiodes, coated with a fluorescent rare earth phosphor. solid state detectors were smaller,


scanners, which provided greater resolution and sensitivity. eventually, both of these technologies were replaced with solid - state detectors : rectangular, solid - state photodiodes, coated with a fluorescent rare earth phosphor. solid state detectors were smaller, more sensitive and more stable, and were suitable for 3rd and 4th generation designs. on an early 4th generation scanner, 600 photomultiplier tubes, ½ in. ( 12 mm ) in diameter, could fit in the detector ring. three photodiode units could replace one photomultiplier tube. this change resulted in increasing both the acquisition speed, and image resolution. the method of scanning was still slow, because the x - ray tube and control components interfaced by cable, limiting the scan frame rotation. initially, 4th generation scanners carried a significant advantage - the detectors could be automatically calibrated on every scan. the fixed geometry of 3rd generation scanners was especially sensitive to detector mis - calibration ( causing ring artifacts ). additionally, because the detectors were subject to movement and vibration, their calibration could drift significantly. all modern medical scanners are of 3rd generation design. modern solid - state detectors are sufficiently stable that calibration for each image is no longer required. the 4th generation scanners ' inefficient use of detectors made them considerably more expensive than 3rd generation scanners. further, they were more sensitive to artifacts because the non - fixed relationship to the x - ray source made it impossible to reject scattered radiation. another limiting factor in image acquisition was the x - ray tube. the need for long, high intensity exposures and very stable output placed enormous demands on both the tube and generator ( power supply ). very high performance rotating anode tubes were developed to keep up with demand for faster imaging, as were the regulated 150 kv switched mode power supplies to drive them. modern systems have power ratings up to 100 kw. slip - ring technology replaced the spooled cable technology of older ct scanners, allowing the x - ray tube and detectors to spin continuously. when combined with the ability to move the patient continuously through the scanner this refinement is called helical ct or, more commonly, spiral ct. multi - detector - row ct systems further accelerated scans, by allowing several images to be acquired simultaneously. modern scanners are available with up to 64 detector rows / output channels ( depends upon the technology used by the manufacturer ). it is possible to complete a scan of the chest in a few seconds. an examination that required


images to be acquired simultaneously. modern scanners are available with up to 64 detector rows / output channels ( depends upon the technology used by the manufacturer ). it is possible to complete a scan of the chest in a few seconds. an examination that required 10 separate breath - holds of 10 seconds each can now be completed in a single 10 second breath - hold. multi - detector ct can also provide isotropic resolution, permitting cross - sectional images to be reconstructed in arbitrary planes ; an ability similar to mri. more anatomical volume coverage in less time is one of the key features of the latest generation md ct scanners. it is however more important to achieve better spatial resolution than only volume coverage for better reconstructed images. latest generation md ct scanners with flying x - ray tube focal spot in z - axis direction shows better image resolution. a different approach was used for a particular type of dedicated cardiac ct technique called electron - beam ct ( also known as ultrafast ct, and occasionally fifth generation ct ). with temporal resolution of approximately 50 ms, these scanners could freeze cardiac and pulmonary motion providing high quality images. only one manufacturer offered these scanners ( imatron, later ge healthcare ), and few of these scanners were ever installed, primarily due to the very high cost of the equipment and their single - purpose design. rapid development of mdct has significantly reduced the advantage of ebct over conventional systems. contemporary mdct systems have temporal resolution approaching that of ebct, but at lower cost and with much higher flexibility. because of this, mdct is usually the preferred choice for new installations. improved computer technology and reconstruction algorithms have permitted faster and more accurate reconstruction. on early scanners reconstruction could take several minutes per image, a modern scanner can reconstruct a 1000 image study in under 30 seconds. refinements to the algorithms have reduced artifacts. dual source ct uses 2 x - ray sources and 2 detector arrays offset at 90 degrees. this reduces the time to acquire each image to about 0. 1 seconds, making it possible to obtain high quality images of the heart without the need for heart rate lowering drugs such as beta blockers. a dual - source multi - detector row scanner can complete an entire cardiac study within a single 10 second breath hold. volumetric ct is an extension of multi - detector ct, currently at research stage. current mdct scanners sample a 4 cm wide volume in one rotation. volumetric ct aims to increase the scan width to 10 - 20 cm, with current prototypes using 256 detector - rows


extension of multi - detector ct, currently at research stage. current mdct scanners sample a 4 cm wide volume in one rotation. volumetric ct aims to increase the scan width to 10 - 20 cm, with current prototypes using 256 detector - rows. potential applications include cardiac imaging ( a complete 3d dataset could be acquired in the time between 2 successive beats ) and 3d cine - angiography. in recent years, tomography has also been introduced on the micrometer level and is named microtomography. but these machines are currently only fit for smaller objects or animals, and cannot yet be used on humans. - cardiology diagnostic tests and procedures - computed tomography laser mammography ( ctlm ) - medical ultrasonography - magnetic resonance imaging ( mri ) - positron emission tomography ( pet ) - single photon emission computed tomography ( spect ) - electron - beam computed tomography ( ebct ) - digitally reconstructed radiograph - synchrotron x - ray tomographic microscopy references & bibliographyedit - ctisus comprehensive ct site by dr. elliot fishman of johns hopkins university - multislice ct angiogram from angioplasty. org - radiologyinfo - the radiology information resource for patients : computed tomography - example ct scan | this page uses creative commons licensed content from wikipedia ( view authors ). |


published a paper ( pdf ) comparing performance of four programming languages, c + +, its own language go, java and scala. a team at google created a " simple and compact " benchmark that didn ' t take advantage of language - specific features. an algorithm was implemented using each language ' s " idiomatic container classes, looping constructs, and memory / object allocation schemes. " google has however, the paper notes : " while the benchmark itself is simple and compact, it employs many language features, in particular, higher - level data structures ( lists, maps, lists and arrays of sets and lists ), a few algorithms ( union / find, dfs / deep recursion, and loop recognition based on tarjan ), iterations over collection types, some object oriented features, and interesting memory allocation patterns. " above : run - time measurements, including a few optimizations. after benchmark tests were published within google various employees took a stab at optimizing the code for specific languages. - c + + provides the best performance by far, but it requires the most extensive language - specific tuning. - scala provides the most concise notation and optimization of code complexity. - the algorithm was simplest to implement in java, but garbage collection settings make both java and scala difficult to benchmark accurately. - go offers concise notion and very fast compile time, but is still immature. the phrase " lies, damn lies and benchmarks " is by now a cliche. suffice it to say, benchmarks never tell the full story, and there are many factors to consider when choosing a programming language. that said, you may find parts of this paper enlightening, especially with regards to scala performance.


type of culminating activity doctor of education in curriculum and instruction curriculum, instruction, and foundational studies jennifer snow, ph. d. critics of the american education system point to student boredom, lack of personalized and relevant instruction, and a deficit of 21st century skills as challenges to producing productive citizens of a modern, digital society ( barab et al., 2009 ; eccles & wingfield, 2002 ; ketelhut, 2007 ; u. s. department of education office of educational technology, 2010 ). digital learning, including game - based approaches, offers opportunities to bring about meaningful, engaging, individualized learning ( barab & dede, 2007 ; gee, 2005 ; squire, 2003 ). quest - based learning is an instructional design theory of game - based learning that focuses on student activity choice within the curriculum, which offers promising pedagogical possibilities in the area. this study expands upon current research of video game characteristics and variables of attractiveness in learner choice. identifying these attractive characteristics in game - based educational design can increase engagement ( barab et al., 2009 ), educational effectiveness ( sullivan & mateas, 2009 ), and impact instructional design decisions. quests were coded and tagged to identify features and attributes. an educational quest taxonomy was developed building on merrill ’ s knowled ge object ( redeker, 2003 ; wiley, 2000 ) classification and expanded to include current digital tools and thinking. electronically collected decision data from a quest - based learning management system was analyzed using descriptive statistical analysis and data mining techniques. educational quests were differentiated by a number of data points and identified as more or less attractive using an initial interest score and a completion score. user rating was also considered for descriptive purposes. data mining and text mining highlighted the specific characteristics of attractive quests including clusters of characteristics identified as most attractive as well as their significance. suggestions for future attractive quest - based learning design are suggested. ( keywords : quests, quest - based learning, game - based learning, 3d gamelab, play styles, learner preferences, rewards, badges, gamification, mmorpgs, virtual environments, informal learning. ) haskell, charles christopher, " design variables of attraction in quest - based learning " ( 2012 ). boise state university theses and dissertations. paper 285.


herschel space observatory launch date : may 14, 2009 mission project home page - http : / / herschel. jpl. nasa. gov / herschel ' s infrared image of the andromeda galaxy shows rings of dust that trace gaseous reservoirs where new stars are forming and xmm - newton ' s x - ray image shows stars approaching the ends of their lives. both infrared and x - ray images convey information impossible to collect from the ground because these wavelengths are absorbed by earth ' s atmosphere. credits : esa / herschel / pacs / spire / j. fritz, u. gent / xmm - newton / epic / w. pietsch, mpe the herschel space observatory is a space - based telescope that is studying the light of the universe in the far - infrared and submillimeter portions of the spectrum. it is revealing new information about the earliest, most distant stars and galaxies, as well as those closer to home in space and time. it is also taking a unique look at our own solar system. herschel is the fourth cornerstone mission in the european space agency ’ s horizon 2000 program. ten countries, including the united states, participated in its design and implementation. launched on may 14, 2009, the mission will operate until the cryostat runs out of helium during the first half of 2013. the mission will operate until the cryostat runs out of helium, perhaps four years after launch. originally called “ first, ” for “ far infrared and submillimeter telescope, ” the spacecraft was renamed for britain ’ s sir william herschel, who discovered in 1800 that the spectrum extends beyond visible light into the region we today call “ infrared. ” herschel ’ s namesake will give scientists their most complete look so far at the large portion of the universe that radiates in far - infrared and submillimeter wavelengths. with a primary mirror 3. 5 meters ( approximately 11. 5 feet ) in diameter, herschel is the largest infrared telescope sent into space as of its launch date. using detectors cooled to temperatures very close to absolute zero ( 0 degree kelvin ), the three instruments called hifi, spire, and pacs, which enables herschel to be the first spacecraft to observe in the full 60 - 670 micron range. the far - infrared and submillimeter wavelengths at which herschel observes are considerably longer than the familiar rainbow of colors that the human eye can perceive. yet, this is a critically important portion of the spectrum to scientists because it is the frequency range at which


far - infrared and submillimeter wavelengths at which herschel observes are considerably longer than the familiar rainbow of colors that the human eye can perceive. yet, this is a critically important portion of the spectrum to scientists because it is the frequency range at which a large part of the universe radiates. much of the universe consists of gas and dust that is far too cold to radiate in visible light or at shorter wavelengths such as x - rays. however, even at temperatures well below the most frigid spot on earth, they do radiate at far - infrared and submillimeter wavelengths. stars and other cosmic objects that are hot enough to shine at optical wavelengths are often hidden behind vast dust clouds that absorb the visible light and re - radiate it in the far - infrared and submillimeter range. last updated : october 26, 2012 - esa herschel website - http : / / www. esa. int / specials / herschel / index. html - more about herschel - http : / / www. nasa. gov / mission _ pages / herschel / index. html - science @ esa - iso / herschel video - http : / / astronomy2009. esa. int / science - e / www / object / index. cfm? fobjectid = 44698 & fattributeid = 885


is that so much of the ocean is invisible to us on a day - to - day basis ; if you don ’ t know what ’ s there, you don ’ t know what you ’ re destroying. the spade - toothed beak whale, which was written up in the new issue of current biology, is a lesson both in the diversity of the fragile oceans and the painstaking sleuthing that is required to study it. after van helden received his early - morning call, he and his colleagues got to work. they gathered all the information they could about the beached pair, including measurements and a set of photographs taken at the scene of the beaching. they worked with the whakatohea iwi, the maori tribe in the area where the whales had been found, and the new zealand department of conservation, to get the skeletons exhumed, and van helden produced a detailed anatomical illustration of the animal, which also appears in current biology. the pair on the beach were an adult female, measuring just over 17 ft. ( 5. 3 m ), and a juvenile male, 11. 5 ft. ( 3. 5 m ) from beak to tail fin. they lack the species ’ signature protruding teeth, which occur only in adult males. the shape and coloration of both specimens are subtly different from other beaked whales — subtle enough, in fact, that they would be easy to confuse with the more commonly seen gray ’ s. ( video : dolphins chased by killer whale ) what allowed the team to make a firm identification was the genetic information collected from the three bones that until now have been our only evidence of the spade - toothed ’ s existence. the first sign of the animal was a lower jaw found on new zealand ’ s chatham islands in 1872, bearing two jutting, triangular teeth. later on, two skulls without lower jaws, one found in 1950 in new zealand, the other found all the way across the pacific on robinson crusoe island in 1986, were proven by dna analysis to be from the same distinct species. but while scientists made educated guesses about what an intact spade - toothed would look like, extrapolating from its relatives could take them only so far. that ’ s why this find had the team so excited. “ it was the first time ever that anybody had ever had even a hint of what these things looked like, ” van helden says. the new discovery is a big step forward for scientists interested in beaked whales, but there is still much to learn about


several workers were evacuated on sunday morning at the fukushima nuclear plant after the level of radioactivity exceeded 10 million times the normal. the water used to cool the reactor number two was found extremely high amounts of particles of radioactive iodine. measured in samples from the water, found in the basement of the turbine hall located behind the reactor is milisievert 1, 000 per hour, said a spokesman for tokyo electric power company ( tepco ). “ this figure is ten million times greater than the radioactivity found in water in a reactor generally in good condition, ” he explained. according to him, the fuel in the reactor core has probably suffered damage during an onset of fusion, occurred immediately after an earthquake followed by tsunami on 11 march. the intervention teams began to use fresh water to cool reactors. this is because sea water that used to accelerate corrosion and could now pose a threat. the government in tokyo has announced that the efforts of japanese workers at fukushima daiichi nuclear power plant, to cool the reactors suffered a new blow on friday after a senior official said the reactor vessel 3 was damaged. hidehiko nishiyama, deputy director of the japanese agency for nuclear and industrial safety, explained that the possibility exists that radiation emanated from the reactor fuel – a mixture of uranium and plutonium – to be released


from january 1 – 14, a reddit user named vidzilla posted daily images of a zombie pandemic as depicted through screen shots of popular internet services. the lessons we can learn from the “ day ” series creative gestalt are an excellent example of why technologists, educators, and the general public should fight for positive rights to fair use. like many internet memes, each of the images from the “ day ” series is a combination of popular and folk culture, a mashup of objects from media industries with new material from the author. many of the individual parts of the “ day ” series ’ images are trademarked and / or subject to copyright, and thus despite the long - standing convention of fair use, the alarming upswing of attempts at regulatory control of content ( sopa, pipa, acta, tpp ) could end up crushing this form of creativity. these digital objects that made up the “ day ” series comprised a 14 day amateur take on the alternative reality game ( arg ) genre. args are interactive narratives revealed by clues delivered across multiple media formats. they are often used in viral marketing campaigns. when the “ day ” series began, some redditors wondered if the posts were viral marketing for the upcoming world war z film. vidzilla claimed to have been influenced by prior args, but emphatically denied that the “ day ” posts were part of a marketing campaign. rather, vidzilla explained, the “ day ” series was an opportunistic creation. after positive responses to an initial post to reddit about text - messaging being the start of a zombie pandemic, vidzilla spontaneously decided to develop a story by by depicting zombie - themed posts in various social media. the inclusion of clues to easter eggs ( hidden extra images, audio, and video ) in the images boosted the popularity of the later posts. reddit users moved from mere upvoting and general discussion of the posts ’ contents to swapping the passwords for audio and video files, debating the meaning of the ambiguous sounds and images, and developing their own responses to the story. on january 15 vidzilla ended the series and thanked the reddit community. the social media patchwork and emergency management the “ day ” series began and ended with fictious sms messages and covered virtually every form of online media in between. each image was a note - perfect slice of the pandemic from the personal to institutional. for example, these first two images


to find. if real - time video feeds showed many people being shocked at once, this could trigger an alert for a human to look at the feeds or for other information. however, as one reddit user pointed out, the particular image of shock in the found footage used to create the chatroulette zombie image was likely drawn from a reaction to nudity in the real chatroulette. the chance for false positives based on just ‘ shocked looks ’, then, and perhaps the range of other discrete reactions, is unfortunately very high. i concede that this scenario is somewhat far - fetched. it is, nonetheless, illustrative of the complexity of sorting markers of a crisis out given the extreme nature of a large amount of the communication exchanged daily online. fiction, in this case, has unwittingly presented an interesting challenge to social media emergency management. the future of education as a communication technology educator, to me one of the most interesting aspects of “ day ” was just how much vidzilla and the responding redditors needed to know about social media to produce and engage with the story. vidzilla ’ s posts succeed because they clearly display generic conventions of form and content of each internet medium. from a media education standoint, such distinctions are the basis of understanding media choices and how culture is ( re ) produced online. indeed, despite the complexity of the scenario discussed above, vidzilla ’ s “ day ” series did, in fact, demonstrate a range of quite plausible crisis markers from which future models could be extrapolated. although vidzilla skipped the intermediate steps of literature reviews and methodology, and had no intention of conducting any analysis of the recognisablity of the markers, the positive response of redditors indicates that vidzilla was on the right track. vidzilla ’ s demonstration of applied media understandings goes beyond the crisis markers. many of the images reproduce famous and current internet trends and memes. vidzilla produced applied media research that many media educators would be proud to see from a student. the “ day ” series posts also mimiced typical reddit posts. reddit bills itself as “ the front page of the internet ” because it is perhaps the most mainstream aggregation of the latest internet trends and world news. vidzilla ’ s knew what redditors would expect to see posted during an emergent crisis. finally, vidzilla ’ s decision to make some of the story materials available via image hosting and


the minds of some individuals than the words of the gospel or that of councils and popes. ironically, the piety which is thus exalted is actually weakened, in the long run, if it is emphasized at the expense of familiarity with the apostolic and ecclesiastical testimony from which its very justification and value is derived. in other words, neglect of the ground of the faith in exchange for an exclusive or exaggerated commitment to a particular pious practice, even one which has the highest backing of the church, may well bring that specific practice itself into question over time. critics of the roman school claim that the piety thus inspired was an egotistical one, centered upon individual devotions and stressing self - sanctification at the expense of a more balanced appreciation of the unity of all believers in that communal enterprise of adoration of the true god from which personal sanctification flows. this self - centeredness was then said to stand as an obstacle to true liturgical revival. one might well note in passing, however, that such a complaint seems to contradict or at least weaken the argument that adulation of the character of the church gradually obscured interest in personal union with christ. a third potential defect of the roman school, and an ironic one, is its rationalism. despite the fact that the enlightenment and its heritage are often popularly thought to have been rationalist in character, the " age of reason " was, in fact, reductionist in its arguments, allowing scope for only one kind of experimental reasoning to flourish. this experimental reasoning soon began to understand human life as something hopelessly enchained to passion, will, subjective value judgment, and irrationality. nineteenth century catholicism, on the other hand, was one of the few forces defending the objective value and significance of the human reason as such. the first vatican council gave eloquent testimony to this fact with its dogmatic constitution concerning the catholic faith, which reiterated the church ' s belief that reason could prove the existence of god. the problem lay not in this defense of reason, but in the tendency by the end of the century and the beginning of the next to focus on one specific line of speculative reasoningthomistto the exclusion of other philosophical approaches. this exclusivity was accompanied by a neglect of historical and other studies which would have helped to reveal the inadequacy of such a development. thus, it was often only with great difficulty, and with accusations of suspicious orthodoxy to boot, that one could speak of the historical context in which men like st. thomas a


would have helped to reveal the inadequacy of such a development. thus, it was often only with great difficulty, and with accusations of suspicious orthodoxy to boot, that one could speak of the historical context in which men like st. thomas aquinas wrote, suggest that this context necessarily limited the completeness of their work, and argue that their labor could well be complemented by the efforts of other thinkers of other eras. to say that the method and writings of st. thomas are not in and of themselves completely sufficient, to argue that they do not by themselves alone give the fullest possible expression to the christian faith, to discuss the historical circumstances in which st. thomas labored and how these may have limited the scope of the questions to which he directed his attention, is not at all the same as saying that thomism is wrong or beside the point. similarly, to say that knowledge of christian dogma might grow beyond the manner in which st. thomas expressed it is not the same thing as denying to dogma an objective, god - given content, anymore than appreciation of st. thomas ' s doctrinal use of aristotelian language amounts to a denial of the divine character of the non - aristotelian doctrinal statements of the apostles. still, such inferences were often drawn by many members of the roman school, with the consequence that any non - thomistic, biblical, patristic, experiential, or historically - based exploration of the faith, was often condemned as " modernist " or intrinsically invalid. this proved to be especially unfortunate when clever students, realizing the gaps in their education, confronted less than gifted teachers who failed to address real problems in a substantive way, and yet presented their work as " authoritative ". it was under circumstances such as these, by the 1890 ' s, that students were seduced by true heretics with superior teaching skills and charismatic personalitiesmen such as the scriptural scholar alfred loisy ( 1857 - 1940 ). neo - ultramontanism also had its negative side which, alas, has become more clear to traditionalist catholics in recent times. like all centralizing movements, it caused problems at the diocesan level, hampering the development of local initiative. this was not so much due to the disturbing but ultimately salutary rocking of the many rather listless parochial boats of the day, as it was to a gradual encouragement of the hope that rome could handle all future problems on its own. when rome could not do so, or


to the disturbing but ultimately salutary rocking of the many rather listless parochial boats of the day, as it was to a gradual encouragement of the hope that rome could handle all future problems on its own. when rome could not do so, or when rome itself became a source of confusion, local clerical and lay stimulus to confront debilitating crises was often therefore missing. moreover, the manner in which the definition of papal infallibility was " resolved " at vatican one was itself problematic. official plans had called for a general schema on the nature of the church to be discussed and promulgated at the council, and it was into this schema that the issue of papal infallibility was introduced. difficulties arose, however, due to intense lobbying for and against the doctrine, inside and outside the council. problems also accompanied the lifting of the discussion of papal infallibility from the basic explanatory framework in which it was embedded, and treating it on its ownfirst, and out of context. the storm grew more violent still. when it was calmed, the resulting definition in no way met the expectations of more fervent infallibilists. fallout from the franco - prussian war then shut the holy synod down, leaving the schema on the church a schema alone. vatican one did indeed bequeath the catholic world a real understanding of the importance of papal power and prerogatives, but failed adequately to explain how these were to be practiced, and what relation they had with the work of ordinary bishops in their own dioceses. it especially left a certain confusion about how infallibility applied to the use of the ordinary magisterium, feeding that constant debate over whether or not it actually had been invoked in specific matters that we have witnessed for one hundred thirty four years. parenthetically, however, in defense of the council ' s procedure, one ought to note that all such synods have tended to treat issues as they arose, in the envelope of ecclesiastical crisis. all have thus left terrible conundrums for posterity. still, the confusion was real, and many romanists acted, unjustifiably, as though the maximalist position which had definitely not been adopted by the council was the one that " real catholics ", in practice, were obliged to accept anyway. fifthly, the call for transformation of everything in christ through the activity of a mobilized laity had the undesired consequence of promoting laicization within the church. such difficulties were not new. they have


leadership involves defining and communicating an organization ’ s long - term vision and mission while conflict resolution typically deals with the situation at hand. by articulating what you want to accomplish, providing support for talented subordinates, overcoming obstacles, exploiting opportunities, demanding excellence, behaving ethically, you set a good example for your organization. an effective leader builds teams that work well together. as a leader, you facilitate the resolution of conflicts that distract the team members, decrease productivity, destroy motivation and lead frustration and anger. you also recognize that some conflict is natural and necessary to produce innovative solutions to problems, encourage meaningful communication between team members and leads to clarification and cooperation. using the thomas - kilmann conflict mode instrument, developed in the 1970s by conflict resolution experts kenneth w. thomas and ralph h. kilmann, you can identify the best way to handle conflict in your organization. leaders use their position, expertise or persuasive ability to exercise control over their subordinates. in an emergency situation, when a decision needs to made quickly, you typically use the autocratic leadership style to resolve the problem. on an ongoing basis, however, to prevent conflict from festering in the organization, effective team leaders take the time to gather input from subordinates and refrain from behaving as if decisions represent a win or loss for subordinates. by using the participative leadership style, you foster an environment of cooperation and collaboration that typically enables employees to function effectively as a team. an effective leader quickly diagnoses issues that hinder team productivity, takes prompt corrective action to resolve disagreements and helps the team members to develop the skills necessary to resolve conflicts on their own, without management intervention. by compromising, both sides in a conflict give up something in order to gain an agreement. effective leaders encourage team members to accept concessions when necessary to maintain a level of productivity rather than continuing to debate or argue. they help team members overcome interpersonal conflicts and promote acceptance of other cultures and experiences in the workplace. to meet the needs of the team, a team member may surrender his position. when the stakes are low, accommodating the needs of others can promote harmony and foster a productive work environment. however, long - term conflict can arise if more aggressive individuals take advantage of team members who don ’ t act assertively. effective leaders monitor their team environment and provide coaching and mentoring to members that enables them to function productively together without operating at the expense of others. when a conflict involves a controversial or unpopular decision


a recent study shows that working the muscles may strengthen not only your body, but your brain as wemay improve the brain ’ s ability to think. in past research, lab animals and people generally performed better on cognition tests after engaging in exercise for several weeks. researchers designed an experiment to observe the exact effects of exercise on the brain. using two drugs that simulate the effects of exercise on lab animals for 2 weeks, the experiment confirmed that changes in muscles did indeed affect the mind. the lab animals that received the drugs performed significantly better on tests of memory and learning than control animals that had been idle for the same 2 weeks. the results suggested, however, that exercise may need to be aerobic in order to substantially affect the brain. for more details, go to http : / / well. blogs. nytimes. com / a study conducted in oregon state university has recently observed the positive effects of short bouts of exercise as compared to the recommended 30 minute structured exercise regimen we are usually told to strive for. researchers say that instead of dedicating 30 minutes to exercise all at once, it can be broken up into spurts of physical activity as short as one or two minutes at a time, which at the end of the day can easily add up to 30 minutes. they suggest becoming aware of your ability to add physical movement into any part of your day and making small changes in your normal routine, such as pacing while talking on the phone, taking the stairs instead of the elevator, using a rake instead of a leaf blower, and shopping in stores instead of online. the study found that 43 % of people who engaged in short bouts of physical activity met the physical guidelines of getting 30 minutes of exercise daily. however, less than 10 % of people engaging in longer bouts of exercise met the same federal guidelines. these new findings provide an easy alternative for those of us who don ’ t have the time to fit 30 or more consecutive minutes of exercise into our busy days. for more details, go to http : / / www. sciencedaily. com / releases / 2013 / 01 / 130129100118. htm weight training alone is not an effective way to reduce the risk of heart disease or diabetes if you are overweight, but aerobic training might be, according to a new study from the duke university medical center. participants in the study were divided into three groups for eight months. one group did only resistance training, working out on eight different weight machines three times per week. the second group did two hours of


to a new study from the duke university medical center. participants in the study were divided into three groups for eight months. one group did only resistance training, working out on eight different weight machines three times per week. the second group did two hours of aerobic training per week, and the third group did both programs. people in the weight training group gained an average of 1. 5 pounds, added to their waistline and failed to reduce their risk for heart disease or diabetes. the aerobic training group lost three pounds and a half - inch from their waists, and participants who did both cardio and weights in the study lost four pounds and an inch from their waists. both groups also decreased their risk of illness. although the combination of weight training and aerobic training produced the best results, the study published in the american journal of cardiology says that it is hard to determine whether the difference between the combined group and the aerobic group was due to the combination of training being more effective or simply forcing participants to work out twice as much. “ when weighing the time commitment versus health benefit, the data suggest that at ( aerobic training ) alone was the most efficient mode of exercise for improving cardiometabolic health, ” says the study, titled “ comparison of aerobic versus resistance exercise training effects on metabolic syndrome. ” exercise also plays a prominent role in reducing the risk of sudden cardiac death, which is the result of a sudden loss of heart function due to problems with the heart ’ s electrical impulses, according to another study published earlier this month in the journal of the american medical association. by analyzing data on lifestyle factors of more than 80, 000 women over the span of 25 years, researchers found that those who worked out regularly and also had a healthy body mass index ( under 25 ), did not smoke and ate a well - balanced diet significantly reduced their chances of sudden cardiac death. it ’ s pretty common to be excited when you start a new exercise program. there ’ s hope that you ’ ll finally reach your goals, you ’ re immersed in a new regime, and because you are starting fresh, your mind is a little more engaged and curious to see what ’ s coming next. but after a few months, how do you keep that going? here is a list of 10 ways tostay excited about exercising, and below are some of my favorites that i use too : 1. ) make exercise a part of your schedule. this personally is crucial for me. if i block out the hour, and have a


freighter ( or barge ) was the term given to any spacecraft that was used to transport freight or cargo ( such as parts and supplies ). both legitimate businesspersons and smugglers could be found captaining such transports. freighters were needed from the time space travel began because of the need for supplies to all reaches of the galaxy. freighters usually traveled with hyperdrives because people would often pay more for quick delivery. for obvious reasons, freighters were used mainly for trade. although very few fought in great battles, many freighters did see action. smugglers and legitimate traders alike had some tangles now and then, but freighters were often armed and shielded so that they could resist attempts on their cargo. smuggling was a very prominent criminal fringe activity in the galaxy that involved the transportation of contraband between planets. to do this, a freighter generally of small size such as the millennium falcon, was required to transport the contraband past planetary security forces. some examples of contraband include spice, blasters and medical supplies. smugglers often added upgrades to their ships so that they could beat competitors and outwit planetary security forces. almost every smugglers vessel had improved light speed and sub - light speed drives for increased speed as well as boosted weapons systems to fight their way out of tough situations. another of the most prevalent modifications to a smugglers freighter were numerous secret compartments to hide contraband from security checks while legitimate cargo occupied the cargo bays. on the millennium falcon, these consisted of removable floor plates. some freighters became so heavily modified that the mess of cross wired and non traditional parts prevented starship mechanics from working on them effectively. the smugglers themselves were therefore required to have a detailed knowledge of freighter mechanics and electronics to be able to keep their vessels in working order. most smugglers preferred it this way as they didn ' t trust anyone tampering with their prized possessions. most smugglers freighters required a crew of more than one and as such most smugglers hired a copilot, such as chewbacca on the millennium falcon or the droid le - bo2d9 aboard the outrider. to a smuggler, their freighter was everything ; their job, their home, their lives. many smugglers lived in their freighters as they had no terrestrial home. - star wars : the old republic - tempest feud - the clone wars : decide your destiny : crisis on coruscant - " the heart " - " maze run " — star wars insider 131 - star wars episode iv : a


algoritma nyaeta susunan parentah, nu jumlahna kawates, pikeun ngolah sababaraha parentah nu, sakumpulan data asupanana, bakal ngahasilkeun sarupaning bentuk ahir nu bisa dipikawanoh ; sabalikna ti heuristik. konsep algoritma mindeng digambarkeun ku conto hiji resep, sanajan loba algoritma kacida ruwetna ; algoritma sering miboga lengkah - lengkah anu malikan ( iterasi ) atawa merlukeun kaputusan ( saperti logika atawa perbandingan ) nepi ka tugas direngsekeunnana. | artikel ieu keur dikeureuyeuh, ditarjamahkeun tina basa inggris. bantosanna diantos kanggo narjamahkeun. sababaraha alogaritma bisa anggeus ku pagawean nu sarua make susunan parentah nu beda in more or less time, space, or effort than others. for example, given two different recipes for making potato salad, one may have peel the potato before boil the potato while the other presents the steps in the reverse order, yet they both call for these steps to be repeated for all potatoes and end when the potato salad is ready to be eaten. correctly performing an algorithm will not solve a problem if the algorithm is flawed or not appropriate to the problem. for example, performing the potato salad algorithm will fail if there are no potatoes present, even if all the motions of preparing the salad are performed as if the potatoes were there. in some countries, such as the usa, some algorithms can effectively be patented if an embodiment is possible ( for example, a multiplication algorithm embodied in the arithmetic unit of a microprocessor ). algoritma nu dirumuskeun [ edit ] algorithms are essential to the way computers process information, because a computer program is essentially an algorithm that tells the computer what specific steps to perform ( in what specific order ) in order to carry out a specified task, such as calculating employees ’ paychecks or printing students ’ report cards. thus, an algorithm can be considered to be any sequence of operations which can be performed by a turing -


in what specific order ) in order to carry out a specified task, such as calculating employees ’ paychecks or printing students ’ report cards. thus, an algorithm can be considered to be any sequence of operations which can be performed by a turing - complete system. typically, when an algorithm is associated with processing information, data is read from an input source or device, written to an output sink or device, and / or stored for further use. stored data is regarded as part of the internal state of the entity performing the algorithm. for any such computational process, the algorithm must be rigorously defined : specified in the way it applies in all possible circumstances that could arise. that is, any conditional steps must be systematically dealt with, case - by - case ; the criteria for each case must be clear ( and computable ). because an algorithm is a precise list of precise steps, the order of computation will almost always be critical to the functioning of the algorithm. instructions are usually assumed to be listed explicitly, and are described as starting ' from the top ' and going ' down to the bottom ', an idea that is described more formally by flow of control. so far, this discussion of the formalisation of an algorithm has assumed the premises of imperative programming. this is the most common conception, and it attempts to describe a task in discrete, ' mechanical ' means. unique to this conception of formalized algorithms is the assignment operation, setting the value of a variable. it derives from the intuition of ' memory ' as a scratchpad. there is an example below of such an assignment. ngalarapkeun algoritma [ edit ] algorithms are sometimes implemented as computer programs but are more often implemented by other means, such as in a biological neural network ( for example, the human brain implementing arithmetic or an insect relocating food ), or in electric circuits or in a mechanical device. the analysis and study of algorithms is one discipline of computer science, and is often practiced abstractly ( without the use of a specific programming language or other implementation ). in this sense, it resembles other mathematical disciplines in that the analysis focuses on the underlying principles of the algorithm, and not on any particular implementation. one way to embody ( or sometimes codify ) an algorithm is the writing of pseudocode. some writers restrict the definition of algorithm to procedures that eventually finish. others include procedures that could run forever without stopping, arguing that some entity may be required to carry out such permanent tasks. in the latter case, success can no longer be


pseudocode. some writers restrict the definition of algorithm to procedures that eventually finish. others include procedures that could run forever without stopping, arguing that some entity may be required to carry out such permanent tasks. in the latter case, success can no longer be defined in terms of halting with a meaningful output. instead, terms of success that allow for unbounded output sequences must be defined. for example, an algorithm that verifies if there are more zeros than ones in an infinite random binary sequence must run forever to be effective. if it is implemented correctly, however, the algorithm ' s output will be useful : for as long as it examines the sequence, the algorithm will give a positive response while the number of examined zeros outnumber the ones, and a negative response otherwise. success for this algorithm could then be defined as eventually outputting only positive responses if there are actually more zeros than ones in the sequence, and in any other case outputting any mixture of positive and negative responses. di dieu aya conto sederhana dina algoritma. bayangkeun anjeun mibanda wilangan random dina daptar nu teu kasortir. tujuan ahirna keur manggihkeun wilangan panggedena tina eta daptar. lengkah mimiti nyaeta kudu nempo kana sakabeh nilai nu aya dina deret. lengkah saterusna nyaeta nempo kana eta nilai ngan sakali. asupkeun kana itungan, algoritma basajan ngeunaan hal eta saperti di handap ieu : - pretend the first number in the list is the largest number. - look at the next number, and compare it with this largest number. - only if this next number is larger, then keep that as the new largest number. - repeat steps 2 and 3 until you have gone through the whole list. given : a list " list " largest = list counter = 2 while counter < = length ( list ) : if list [ counter ] > largest : largest = list [ counter ] counter = counter + 1 print largest notes on notation : - = as used here indicates assignment. that is, the value on the right - hand side of the expression is assigned to the container ( or variable ) on the left - hand side of the expression. - list [ counter ] as used here indicates the


= as used here indicates assignment. that is, the value on the right - hand side of the expression is assigned to the container ( or variable ) on the left - hand side of the expression. - list [ counter ] as used here indicates the counterth element of the list. for example : if the value of counter is 5, then list [ counter ] refers to the 5th element of the list. - < = as used here indicates ' less than or equal to ' note also the algorithm assumes that the list contains at least one number. it will fail when presented an empty list. most algorithms have similar assumptions on their inputs, called pre - conditions. as it happens, most people who implement algorithms want to know how much of a particular resource ( such as time or storage ) a given algorithm requires. methods have been developed for the analysis of algorithms to obtain such quantitative answers ; for example, the algorithm above has a time requirement of o ( n ), using the big o notation with n representing for the length of the list. kecap algoritma comes ultimately from the name of the 9th - century mathematician abu abdullah muhammad bin musa al - khwarizmi. the word algorism originally referred only to the rules of performing arithmetic using arabic numerals but evolved into algorithm by the 18th century. the word has now evolved to include all definite procedures for solving problems or performing tasks. the first case of an algorithm written for a computer was ada byron ' s notes on the analytical engine written in 1842, for which she is considered by many to be the world ' s first programmer. however, since charles babbage never completed his analytical engine the algorithm was never implemented on it. the lack of mathematical rigor in the " well - defined procedure " definition of algorithms posed some difficulties for mathematicians and logicians of the 19th and early 20th centuries. this problem was largely solved with the description of the turing machine, an abstract model of a computer formulated by alan turing, and the demonstration that every method yet found for describing " well - defined procedures " advanced by other mathematicians could be emulated on a turing machine ( a statement known as the church - turing thesis ). nowadays, a formal criterion for an algorithm is that it is a procedure that can be implemented on a completely - specified turing machine or one of the equivalent formalisms. turing ' s initial interest was in the halting problem : deciding when an algorithm describes a terminating procedure. in practical terms computational complexity theory matters more : it includes the puzzling problem of the algorithms