are incubated at room temperature and can be examined microscopically for the motile organisms every two days for 12 days. this test is more sensitive than direct examination of faeces and helpful for detecting infections where direct smears are negative. giardia, and other similar organisms will not grow in this specific culture medium. in the uk, this system was available from capital diagnostics in edinburgh ( 0131 535 3145 ) but its high prevalence of false negatives ( due to the parasite dieing in the cold uk postal system ) means that it is not recommended as the pcr is far more sensitive. the most sensitive and specific test is a pcr ( polymerase chain reaction ) test – a sophisticated test that can detect the presence of the genetic material of the organism. this is an extremely sensitive test that is available in the uk and us from a number of laboratories ( please see below ). current information suggests the long - term prognosis for infected cats is good, and that they will eventually overcome the infection. however, this is a slow process – in one study of infected cats, resolution of the diarrhoea took an average of nine months, with occasional cats having diarrhoea persisting for more than two years, and rarely for life. it appears that most infected cats continue to shed low levels of the organism in their faeces for many months after the resolution of the diarrhoea. most studies on treatment of t. foetus infection in cats have been unrewarding. the organism is resistant to most traditionally used anti - protozoal drugs such as fenbendazole and metronidazole. the use of a variety of different antimicrobial drugs has been reported to improve faecal consistency during therapy of infected cats, possibly because of interaction between t. foetus and the bacteria normally present in the intestine. however, such antibiotic use is not recommended as it may ultimately prolong the shedding of the organism, and does not resolve the underlying problem. a recent study by dr jody gookin at the north carolina state university ( who has performed most of the work on this infection in cats ) identified that ronidazole and tinadazole ( antibiotics similar but not the same as metronidazole ) may have efficacy against t. foetus infection in cats ( jvim, 2006 ; 20 : 536 ; am j vet res, 2007 ; 68 : 1085 ). from limited studies ronidazole appears to be more effective


the vmd have agreed to our use of this chemical in these cats, they strongly recommend that detailed records are maintained and that no cat is treated without first obtaining informed, signed, owner consent. in addition, we should compile data on all potential adverse effects : send case information on any potential adverse effects to danielle. gunn - moore @ ed. ac. uk. care should be exercised in the use of ronidazole, as there are very few studies of its use in cats, and long - term studies in other species have suggested some potential toxicity concerns. ( in many countries its use in food - producing animals has been banned to minimise human exposure ). careful handling of the drug is therefore advised. it should never be given to pregnant queens ( or queens about to be put to stud ) : it is very teratogenic and may result in a number of different and severe defects. anyone handling ronidazole should wear gloves ( especially if they are a woman of reproductive age ). since the diarrhoea usually resolves over time, and is often more of an inconvenience than being associated with significant adverse effects in affected cats, it may not be necessary or advisable to treat all affected cats with ronidazole. using a simple highly digestible diet or a high fibre diet may result in improved faecal consistency, and this may be sufficient to control the clinical signs in some cats. although not proven, it is thought that t. foetus may be able to infect humans ; as a precaution people in contact with infected cats are advised to take basic hygiene precautions to avoid ingesting the parasite. these precautions will also help to prevent the spread of the infection to other cats, and prevent humans from being infected with other infections that the cat may carry. suitable hygiene precautions include : - washing hands thoroughly after handling cat faeces - washing hands thoroughly after cleaning cat litter trays, whether the cat has diarrhoea or not - cat scratches or bites should always be washed immediately with soap and water. seek medical attention as soon as possible if signs of infection appear, such as redness, pain or swelling. - persons with a weakened immune system should not handle their cat ’ s faeces or litter box, they are advised to wash their hands after handling their cats, and they are advised not to keep cats that have persistent diarrhoea. if their cat develop diarrhoea it should be fully investigated and if found to be infected with tritrichomonas foe


wash their hands after handling their cats, and they are advised not to keep cats that have persistent diarrhoea. if their cat develop diarrhoea it should be fully investigated and if found to be infected with tritrichomonas foetus it should be treated with ronidazole and then re - tested, or ( at least temporarily ) re - homed until the infection has resolved. for further information on t. foetus infection in cats : www. fabcats. org. for veterinary surgeons seeking further discussion, contact danielle gunn - moore : email : danielle. gunn - moore @ ed. ac. uk. tel : 44 ( 0 ) 131 650 7650 fax : 44 ( 0 ) 131 650 7652. in the uk this is available from capital diagnostics, sac veterinary science division, bush estate, penicuik, midlothian, eh26 0qe : tel. 0131 535 3145 ). alternatively, a real - time quantitative pcr ( qpcr ) assay is now available, which incorporates an internal amplification control so that false negative results are avoided. the assay is performed on a small volume of faeces ( 2 - 5ml ) at a cost of £29 ( + vat ) ; further details on the test and submission forms can be found on http : / / www. langfordvets. co. uk / lab _ pcrnews. htm or by contacting langford veterinary services diagnostic laboratories at the university of bristol, langford house, langford, bristol, bs40 5du. tel : + 44 ( 0 ) 117 928 9412 fax : + 44 ( 0 ) 117 928 9613 email : firstname. lastname @ example. org. in the us samples can be submitted to the college of veterinary medicine, north caroline state university ( usa ) for this test – information on this is available at : www. cvm. ncsu. edu / mbs / gookin _ jody. htm. thanks to dr andy sparkes, ellie mardell and kirsty wood who were involved with the initial preparation of this paper. dahlgren ss, gjerde b, pettersen hy ( 2007 ) first record of natural tritrichomonas foetus infection of the feline uterus. journal of small animal practice 48 : 654 - 657 foster dm, gookin jl, poore mf, stebbins me, levy mg


of natural tritrichomonas foetus infection of the feline uterus. journal of small animal practice 48 : 654 - 657 foster dm, gookin jl, poore mf, stebbins me, levy mg ( 2004 ) outcome of cats with diarrhoea and tritrichomonas foetus infection. journal of the american veterinary medical association 225 : 888 - 892 gookin jl, breitschwerdt eb, levy mg, gager rb ( 1999 ) diarrhoea associated with trichomoniasis in cats. journal of the american veterinary medical association 215 : 1450 - 1454 gookin jl, birkenheuer aj, breitschwerdt eb, levy mg ( 2002 ) single - tube nested pcr for detection of tritrichomonas foetus in feline faeces. journal of clinical microbiology 40 : 4126 - 4130 gookin jl, copple cn, papich mg, poore mw, stauffer sh, birkenheuer aj, twedt dc, levy m ( 2006 ) efficacy of ronidazole for treatment of feline tritrichomonas foetus infection. journal of veterinary internal medicine 20 : 536 - 543 gookin jl, foster dm, poore mf, stebbins me, levy mg ( 2003b ) use of a commercially available culture system for diagnosis of tritrichomonas foetus infection in cats. journal of the american veterinary medical association 222 : 1376 - 1379 gookin jl, levy mg, law jm, papich mg, poore mf, breitschwerdt eb ( 2001 ) experimental infection of cats with tritrichomonas foetus. american journal of veterinary research 62 : 1690 - 1697 gookin jl, stebbins me, adams e, burlone k, fulton m, hochel r, talaat m, poore m, levy mg ( 2003a ) prevalence and risk of t foetus infection in cattery cats ( abstract ). journal of veterinary internal medicine 17 : 380 gookin jl, stebbins me, hunt e, bulone k, fulton m, hochel r, talaat m, poore m, levy mg ( 2004 ) prevalence and risk factors for feline tritrichomonas foetus and giardia infection. journal of clinical microbiology 42 : 270


, fulton m, hochel r, talaat m, poore m, levy mg ( 2004 ) prevalence and risk factors for feline tritrichomonas foetus and giardia infection. journal of clinical microbiology 42 : 2707 - 2710 gookin jl, stauffer sh, coccaro mr, poore mf, levy mg, papich mg ( 2007 ) efficacy of tinidazole for treatment of cats experimentally infected with tritrichomonas foetus. am j vet res 68 ( 10 ) : 1085 - 8. gunn - moore, da, mccann, tm, reed, n, simpson, ke, tennant, b. ( 2007 ) prevalence of tritrichomonas foetus infection in cats with diarrhoea in the uk. jfms 9 : 214 - 218 gunn - moore da, tennant b. ( 2007 ) tritrichomonas foetus in cats in the uk. vet rec. 160 ( 24 ) : 850 - 851 kather ej, marks sl, kass ph. ( 2007 ) determination of the in vitro susceptibility of feline tritrichomonas foetus to 5 antimicrobial agents. j vet intern med. ; 21 ( 5 ) : 966 - 70 ) levy mg, gookin jl, poore m, birkenheuer aj, dykstra mj, litaker rw ( 2003 ) tritrichomonas foetus and not pentatrichomonas hominis is the etiologic agent of feline trichomonal diarrhoea. journal of parasitology 89 : 99 - 104 mardell ej, sparkes ah. ( 2006 ) chronic diarrhoea associated with tritrichomanas foetus infection in a british cat. veterinary record 158, 765 - 766 romatowski j ( 2000 ) pentatrichomonas hominis infection in four kittens. journal of the american veterinary medical association 216 : 1270 - 1272 rosado tw, specht a, marks sl. ( 2007 ) neurotoxicosis in 4 cats receiving ronidazole. j vet intern med 21 ( 2 ) : 328 - 31 sac ( sac veterinary services ) monthly report ( 2007 ) ; available online www. sac. ac. uk / consultancy / veterinary / publications / monthlyreports / 2007 : veterinary record 161 ( 16 ) : 544 - 54


) : 328 - 31 sac ( sac veterinary services ) monthly report ( 2007 ) ; available online www. sac. ac. uk / consultancy / veterinary / publications / monthlyreports / 2007 : veterinary record 161 ( 16 ) : 544 - 546 figure 1 : rectal smears can be made using cotton swabs rolled over the rectal wall. smears can be made on glass slides, and material obtained should be diluted with saline to prevent desiccation. figure 2 : typical appearance of a large number of t foetus organisms in a faecal smear under x400 magnification. when examined, the organisms can be seen to be highly motile. figure 3 : appearance of an individual t foetus organism stained with lugol ' s iodine. three anterior flagellae can be seen, and an undulating membrane runs the length of the body. information is published on the feline advisory bureau website and can be accessed via the link below : there has been a great deal of news in the press recently about cats being poisoned by antifreeze, both maliciously and accidentally. a spate of publicised incidents was reported in the somerset area, but then seemed quickly to spread to other areas of the country. as with any such event, it is difficult to determine whether the spread of cases was due to copycat poisonings, or simply because the increased publicity increased reporting of more suspected incidents. one hopes the latter. nevertheless, antifreeze products can pose a serious threat to companion animals. antifreeze is reportedly very sweet to taste and presumably palatable, and poisonings in dogs are quite common. cats are at great risk as the fatal dose for ethylene glycol based antifreezes in cats is about 1. 5ml per kg bodyweight, so cats only need to consume about five to six ml – a couple of good licks – to be in immediate and life - threatening trouble. for successful management, intervention must be extremely fast as glycols are readily and rapidly absorbed, with the kidney function becoming rapidly impaired. there are cases of fatality occurring within hours of ingestion. one of the antidotes available for such poisonings is not tolerated by cats at all, so the only therapy left is giving ethanol ( alcohol ), so it is very difficult to treat. there are suggestions that the poisonings could be accidental with the cat drinking from a water feature which has had antifreeze added to stop it freezing up over winter. however, most of


ethanol ( alcohol ), so it is very difficult to treat. there are suggestions that the poisonings could be accidental with the cat drinking from a water feature which has had antifreeze added to stop it freezing up over winter. however, most of these poisonings seem to have happened before the bad weather and only water features without fish or pond life could be treated in this way, as alcohols and glycols permeate fish membranes easily and will affect them. between 2003 and 2007, the veterinary poisons information service ( vpis ) documented 108 antifreeze - related enquiries in cats and 100 in dogs overall – so about 20 cases per annum. 46 of the feline cases and 35 of the canine cases were followed up. of these, 30 of the feline cases were known to have fatal outcomes ( 65. 2 % ) compared with eight known fatal outcomes in dogs ( 22. 9 % ). higher mortality rates have been reported in other published studies from elsewhere. it is sad to report that 2008 was a particularly bad year. up to the end of october, 93 cases had been reported to vpis ( london ) – 56 in cats and 37 in dogs. usually the number of reports rises in the months for october to march, so these numbers are worryingly elevated. case outcome data is not available for all these cases yet – but 12 deaths have been reported in cats from 16 returned case follow - up questionnaires ( 75 % mortality therefore ). the message for cat lovers is to make sure that there is no spillage of antifreeze in garages or sheds or under the car. the fastidious clean cat will groom it off feet if it is walked through. collectively, we must ensure that the message gets out that these chemicals are very dangerous for pets and the cat group, along with vpis, will be raising the issue in the press in the future. the spca in british columbia, canada, has produced a helpful manual and dvd for those working in rescue situations, called catsense™ - the emotional life of cats. the catsense™ manual is a complete guide to putting in place a system for good welfare of cats in a shelter environment. it includes information on housing, behaviour, checklists for stress, and planning to put in place good evidence - based welfare practices. the dvd explains the emotional states experienced by cats in shelters and shows examples of cats displaying anxiety, fear, frustration and depression. a two hour training dvd, presented by nadine gourkow, advises on


the natural objects that i propose to consider are broadly those physical objects which are studied and referred to by science and by a common sense view, informed by science, of the world. natural objects are, philosophically speaking, individuals ; they are involved as units in dynamic, causal processes. i shall draw a distinction between natural objects and the abstract objects of mathematics, in particular set theory. natural objects encompass atoms and molecules ; cells and organisms, including you and me ; the objects of everyday life such as chairs and automobiles ; nations, continents, ecosystems, mountain ranges, geological faults ; planets, stars and galaxies. each natural object, when regarded internally, is a dynamic system with various interacting parts and components ( some of which may be natural objects in their own right ) ; when regarded externally, a natural object acts as a unit with respect to a larger system or systems ( which may again be natural objects ) of which the given object forms a part or component. it is sometimes argued that objects such as atoms or galaxies are theoretical constructs, as much so as mathematical objects ( or even, according to some, more so ). it is true that any reference to an object rests on epistemological assumptions. the approach here will be not to belittle these important epistemological questions but to leave them aside, and accept as a working assumption the practical viewpoint of people who are dealing with the world : that natural objects exist, act, and are acted upon, independently of the observer - - although any description of them or of their actions is dependent on the describer. scientific theories refer to natural objects as well as to abstractions of them ; they also refer to and quantify over other entities, in particular, the real numbers, points in space, time, and other mathematical spaces such as vector spaces, hilbert space, etc. - - these are abstract objects which are not necessarily abstractions of any natural objects. thus the ontology of natural objects may be said to be more restrictive than, say, a quinesque one. my point, however, is again not to dispute the validity of this or that ontology, but rather to describe a level of existence. no judgment will be presumed about the question of what ontological commitment should be made to abstract objects : rather, our focus of attention will be elsewhere. in the examples above and in what follows, i concentrate on physical objects. i do not mean to rule out psychic or spiritual or intellectual objects. you and i, as objects, have these aspects ; french society


our focus of attention will be elsewhere. in the examples above and in what follows, i concentrate on physical objects. i do not mean to rule out psychic or spiritual or intellectual objects. you and i, as objects, have these aspects ; french society, indian classical music, the theory of natural selection, king lear, king lear, the collective unconscious may all be regarded as natural objects. their ties to physical existence ( in the sense of matter and energy ) or to extensional ( spatial ) existence are various, and there is scope for varied theories about their ontological status ; i tend to follow nicolai hartmann ( 1949 ) in assigning to spiritual and psychic strata " categorial dependence " on the strata of physical existence in spaces : thus these objects are tied, however indirectly, to the physical level of existence. what i have to say will apply to such objects, in so far as they are acknowledged to exist ; and even to purely spiritual or psychic objects not tied to the physical level of existence at all, if they are admitted to exist. but i shall keep largely to physical and biological examples as being less problematic. this will also insulate the discussion from problems of consciousness and free will which inevitably come up but are not my concern here. thus the natural objects to be considered here may correspond more or less to the " natural bodies " of francis bacon : " toward the effecting of works, all that man can do is to put together or put asunder natural bodies. " ( bacon 1620, 39 ) an interesting example of a natural object is a hurricane. it is an open system, exchanging matter, energy and information with its environment, and acting as a whole. it is certainly accorded the status of an individual, in everyday language and in meteorology, even to the extent of being given a proper name ( such as floyd, mitch, zeb or babs ). it cannot be precisely identified with any set of atoms or molecules ; and any boundary in space or time that you try to draw for the hurricane will be arbitrary. meteorologists will draw such a boundary - - say, the point in time when a tropical storm is upgraded to a hurricane - - according to conventions about energy content and wind speeds, but the passing of a boundary is merely the employment of a convenient yardstick and is not supposed to have absolute significance. natural objects may usefully be described as systems. von bertalanffy ( 1968 ) defines a system as " a complex of interacting elements " ( although von bertalanffy '


a convenient yardstick and is not supposed to have absolute significance. natural objects may usefully be described as systems. von bertalanffy ( 1968 ) defines a system as " a complex of interacting elements " ( although von bertalanffy ' s elements are not to be equated with elements in the set - theoretic sense, and to avoid confusion i use " components " ). he goes on to study systems defined in terms of partial differential equations. mesarovic and takahara ( 1975 ) develop a more general, set - based concept of system. they are able to define such notions as cascading, feedback, and open systems. natural objects can be named, or they can be defined by ostension. often, naming and pointing will be essentially the only ways to refer unambiguously to a particular object. 2. natural and abstract objects the words " a logic " of the title are intended to suggest the aim of depicting how we reason or infer about natural objects. set theory, as a foundation for mathematics, is a way of doing this for abstract objects. before examining natural objects more closely, i wish to compare them with abstract objects - - which i shall identify, for concision, with sets - - in order to bring out some properties relevant to both. cantor ( 1895 ) introduced the concept of set as " any comprehension into a whole m of definite and separate objects m of our intuition or our thought ", and the modern development of set theory has retained the spirit of cantor ' s conception, in particular through the fundamental role of the comprehension axiom. even in the limited form necessary to avoid the paradoxes, comprehension formalizes the grouping together of objects with like properties into a single entity. the objects - - sets, classes - - of set theory are abstractions, the product of our mental processes ( " our intuition or our thought " ) which impose an organization on the world we perceive. except under a naive platonist interpretation, sets are not required to have an autonomous existence outside the formal system that creates them : that is to say, outside the language of the observer. ( the same goes for all other mathematical objects, including categories. ) thus set theory may be said to be a part of epistemology, the study of our knowledge of the world. following a hint of graham c. d. griffiths ( 1974, 87 ) i wish to contrast this with ontology, the study of what things exist, independently of any observer. from a scientific perspective, objects such


of our knowledge of the world. following a hint of graham c. d. griffiths ( 1974, 87 ) i wish to contrast this with ontology, the study of what things exist, independently of any observer. from a scientific perspective, objects such as atoms, molecules, organisms ( including persons ), stars, galaxies may be said to have an objective individual existence - - although there are borderline cases where the object ' s existence as a separate individual may be questionable, and the individuality of, say, a quark is of a very different nature from yours or mine. on the other hand, sets of objects, such as the set of all stars, or an arbitrary collection of, say, 100 people chosen at random, can exist as individuals only in an abstract sense ( though the former example may be viewed as a natural kind ). in addition, the " definite and separate " character of the elements of a set is not always found in nature where boundaries are generally ill - defined and separation may be relative and time - dependent. natural objects interact, are born of others, and die. to bring out how natural objects in general differ from sets, let me pause to consider the nature of one particular object, myself, whose autonomy and continuity i feel so clearly ( but proceeding in a different direction from descartes ). can i precisely be identified with a set? what about the set of cells that contain my unique dna? this set provides a good approximation to my physical extent, but there are many problems with identifying " me " with this set : i am not trying to attack set theory as such. i simply wish to note that the common mode of talking about the world leaves philosophical doubts aside and names natural objects ; that the language of science is full of them ( as well as of abstract objects ) ; and that set - theoretic language does not capture the nature of natural objects, as of course it was never intended to. it therefore seems worthwhile to try and develop a theory of natural objects. as jody azzouni puts it ( 1994, 4 ), mathematical objects are metaphysically inert. natural objects, by contrast, interact intensively with the rest of the world, and this interaction in fact cannot be separated from their nature. but great care will be needed because once a mathematical framework for referring to these objects has been established, the referents themselves will be mathematical objects. rigorous separation of levels of discourse will be necessary - - but this is nothing new in logic and metamathematics. sets are


needed because once a mathematical framework for referring to these objects has been established, the referents themselves will be mathematical objects. rigorous separation of levels of discourse will be necessary - - but this is nothing new in logic and metamathematics. sets are abstracted ( from the latin : drawn away ) from direct physical experience. a common example frequently seen in expositions of elementary ( naive ) set theory illustrates the abstract nature of the set concept by explaining how a collection of disparate objects can be grouped together into a set merely by enumerating them or by specifying a common property - - no matter how incongruous and varied their natures or how widely separated they are in space and time. this kind of construction is counter - intuitive to a student who is not accustomed to thinking in terms of abstractions ; the natural objects one is used to dealing with in less abstract contexts do not have these properties. even the pair set axiom does not hold, in general, for natural objects. a pair of objects is not, usually, a single object ( although in special cases one will consider certain pairs as a unit ; for example a married couple is an object in legal considerations ). the same goes for other elementary set - theoretic constructions such as unions and intersections. the distinction between individuals and classes is relevant here. ( some philosophers talk of natural kinds ; others oppose individuals to " sets ". ) this distinction, which goes back to plato and aristotle, was blurred by cantor : his sets are both individuals and classes. indeed, the principle of comprehension is a formalization of the notion that a class of objects is defined, as an individual, by a common property that they share. the subsequent development of set theory reinstated the individual / class distinction in a different form with sets and proper classes ; this happened as early as cantor ( 1899 ). different versions of modern set theory ( zermelo - fraenkel, von neumann - bernays - godel ) vary in the ontological status accorded to proper classes, as do different interpretations of the formalisms. however, the basic point here is that sets are essentially collections ( " multiplicities " - - cantor ) treated as individuals. a natural object is never merely a collection ; the interaction of its components is an essential part of its individuality. it is perhaps of interest to note that ernst zermelo, in his fundamental paper ( 1908 ) on axiomatizing set theory, seemed to be open - minded about whether all objects are sets : "


an essential part of its individuality. it is perhaps of interest to note that ernst zermelo, in his fundamental paper ( 1908 ) on axiomatizing set theory, seemed to be open - minded about whether all objects are sets : " set theory is concerned with a domain b of individuals, which we shall call simply objects and among which are the sets. " ( emphases in original. ) for zermelo, the membership relation is fundamental ; sets are defined in terms of this relation, as objects which have elements, so that a special case is needed for the empty set. so sets are logically posterior to, not prior to, the fundamental binary relation. but unlike later authors zermelo does not rule out the possibility that some objects are nonsets. of course the nonsets which he had principally in mind were atoms or urelements ; these have continued to play a role in set theory, but only in connection with the membership relation. other possible relations or properties of urelements are not considered. natural objects may be urelements - - the raw material for forming sets - - for example, the set of all hurricanes in 1999 may be used, and abstracted, in a statistical analysis. what interests me here is not the properties of natural objects qua urelements, but what other properties they may have, orthogonal as it were to their set - theoretic ones, because not expressed in terms of the membership relation. as a first approximation, let us suppose that an appropriate language for natural objects has a binary relation, analogous to the fundamental binary relation ( " x is an element of y " ) of set theory, but stating rather " x is a component of y ". this relation will have very different properties from. in fact partakes of some of the properties of natural objects : it changes through time and space. its properties in the subatomic and the macroscopic realms diverge. but we can certainly see whether set - theoretic ideas apply to, exploring the correspondence, more than an analogy, between and. as intimated above, basic set - theoretic axioms including comprehension and the pair set axiom do not hold for natural objects under this - interpretation. there is something of a tradition of alternate set theories in which some of the standard axioms are negated. we may gain clues about reasoning with natural objects from what has been learned about reasoning with weak sets. one important line of work in this direction negates the axiom of foundation


set theories in which some of the standard axioms are negated. we may gain clues about reasoning with natural objects from what has been learned about reasoning with weak sets. one important line of work in this direction negates the axiom of foundation. this has been most successfully done by peter aczel ( 1988 ), building on work of boffa ( 1969 ), forti and honsell ( 1983 ), finsler, scott, and others. aczel ' s work in turn has had important applications in situation theory, theory of communicating systems, and elsewhere ( e. g. barwise 1989, barwise and moss 1998 ). aczel has built a universe of set theory, extending and not supplanting the standard universe of set theory, that provides a useful formalism for certain ways of looking at the world ( e. g. situation theory ). the axiom of foundation was historically one of the last of the standard axioms of set theory to be added to the canon. the axiom of choice was introduced earlier ( choice : zermelo 1904 ; well - foundedness and foundation : mirimanoff 1917, skolem 1922 ), but its separate status was recognized from the start, and has, of course, been a central theme in 20th century set theory. other authors have more recently examined the independence of some of the core axioms of set theory from weak base systems, thus bringing into question even these axioms that were, unlike choice, readily accepted. for example, boffa ( 1972 ) proved an independence result concerning the pair set axiom ; gonzalez ( 1992 ) showed the independence of the union axiom in zermelo set theory, using a permutation method ; zarach ( 1998 ) used forcing to show that collection is not implied 3. species and the indescribability in this and the next section i turn from a comparison with set theory to motivating influences from the sciences. problems of behaviour of natural objects, and of the constitution of an individual, have arisen in concrete situations, and i shall attempt to draw some working principles from these lessons. an important case study in the investigation of natural objects is the work of philosophers of biology on the nature of individuals. this has arisen in large part because a set - theoretic framework has been found by many to be inadequate for the ontological status of taxonomic groups. in particular, the traditional conception, which goes back to aristotle, of each species as a class has been questioned, first by michael


a set - theoretic framework has been found by many to be inadequate for the ontological status of taxonomic groups. in particular, the traditional conception, which goes back to aristotle, of each species as a class has been questioned, first by michael ghiselin ( 1966 ; see also 1974, 1981, 1987 ), and then by many other authors ( e. g. holsinger 1984, hull 1978, sober 1984, sober 1993, griffiths 1974 ). they point out that to consider a species as a class, or as defined by a set of properties, is to impose on it a character that it does not have, and to miss the actual nature of species. since darwin we know : this has the added advantage of unifying the biological hierarchy of entities : at each level - - cell, organism, population, species, etc. - - there occur individuals that are defined, not by comprehension in terms of their elements ( this is impossible ), but as dynamical, changing systems whose behaviour can be characterized internally by interactions among their components, or externally by their interactions with their environment. indeed, one can extend this hierarchy to the physical level ( s ) as well ( molecules, atoms,... stars, galaxies,... ) with the same remarks still holding ( griffiths 1974 ). ghiselin ( 1987, 128 ) goes so far as to say that treating species as individuals opens " the prospect that we can develop a single body of knowledge for the entire universe. " thus the practical pursuit of systematics in biology broadens into a picture of the universe as consisting of individuals, each individual being bounded in space and time but not ( necessarily ) contiguous or connected, characterized by a dynamical interplay of its components and its environment, and definable by ostension or by naming and not by comprehension : when anyone tries to find the " defining properties " of an individual, he is wasting his time. this is equally true for homo sapiens, tellurian life, human language, french, and noam chomsky. ( ghiselin 1981, 283 ) another biological science, ecology, similarly encourages us to view biological systems as wholes, with components that are dynamically interdependent ( e. g. levins and lewontin 1980 ). the notion of supervenience ( kim 1978 ) is a good candidate for formalization in any attempt to describe the articulation of the different levels of the hierarchy of natural objects. an important principle suggested by all the above discussions is


1980 ). the notion of supervenience ( kim 1978 ) is a good candidate for formalization in any attempt to describe the articulation of the different levels of the hierarchy of natural objects. an important principle suggested by all the above discussions is the inadequacy of any ( finite ) language to describe any natural object fully, other than by naming or ostension. everyday life, and the example of " me ", tend to confirm this principle ; and of course it is fundamental to quantum mechanics as expressed in the uncertainty principle and complementarity, construed ( as in the copenhagen interpretation ) as precluding a complete objective description of phenomena : i shall say more on this in the next section. the principle of the indescribability of objects provides a contrast between natural objects and abstract objects : in set theory, the exact specification and construction of objects using comprehension and the other constructive axioms is essential. a second principle is, in contrast, shared by natural and abstract objects. in fact it is suggested both by set theory and by recent work in cosmology. cosmologists are facing more and more consciously the problem of describing everything. set theory, among other branches of mathematical logic, has a similar ambition in that an entire universe is to be constructed - - not in this case the physical universe but the " universe of discourse " of mathematics, the aggregate of all the abstract objects studied by mathematicians. incidentally, the habitual use of the term " universe " for the class of all sets is relatively recent. zermelo ( 1908 ) merely spoke, as we have seen, of a " domain " of individuals ; russell and whitehead in principia mathematica ( 1910 ) referred to the " universal class " v, and even godel in his work on v = l, which set the tone for all subsequent set theory, refers to the " universal class " and not the " universe " ( godel 1940, 40 ). the principle i am proposing here is the impossibility of describing everything. in set theory, it was necessitated by the early paradoxes and is articulated in a fundamental series of theorems, including those of lowenheim - skolem, of godel, and the related result of tarski on the undefinability of truth ( these are not confined to set theory ). even before these results, it was realized that sets have a way of spilling over any circumscription that one may attempt to put on them :...


undefinability of truth ( these are not confined to set theory ). even before these results, it was realized that sets have a way of spilling over any circumscription that one may attempt to put on them :... quel que soit l ' ensemble qu ' on envisage ( pourvu qu ' il existe ), des individus nouveaux surgissent, et un ensemble plus vaste apparait necessairement ; on est bien en presence d ' une extension indefinie qui ne comporte pas d ' arret ni borne. ( mirimanoff 1917, 48 ) since godel ' s work, there has been what akihiro kanamori ( 1996, 46 ) calls a " cornucopia of models of set theory " ( i. e. models of everything ) and in fact these are a basic research tool. in cosmology, the attention of some researchers has been focussed more recently on the problem of everything. it arises acutely when the universe ( defined, perhaps, as what emerged from the big bang ) turns out not to be everything : when in order to account for the observed properties of our universe, it is found that the best explanation is a theory incorporating the existence of many universes, of which ours is just one. several modern cosmological theories call for multiple universes, including lee smolin ' s theory of the creation and natural selection of universes ( smolin 1997 ). andrei linde ' s " chaotic inflation " and " eternally self - reproducing universe " ( e. g. linde 1990 ) also call for many, perhaps infinitely many, universes - - if by universe we mean everything that we can in principle communicate with. smolin ( 1997, 14 ) has addressed the issues that emerge when attempting to describe everything : the problem of how to make a theory of the whole universe is thus the problem of how to construct a theory without making any reference to anything that exists, or anything that we might have imagined happened, outside of the system we are describing. a related lesson is taught by quantum theory ; thus heinz r. pagels ( 1982, 103 ) : bohr ' s principle of complementarity implies that knowing everything at one time about the world - - a requirement of determinism - - is impossible because the conditions for knowing one thing necessarily exclude knowledge of others. the separation of observer and observed, in the copenhagen interpretation, carries the


expressed in terms of a space and time that were absolute and prior to the physical universe. newton himself realized this and had recourse to a metaphysical notion of space and time. leibniz also realized it and made it a central part of his criticisms of the newtonian cosmos, proposing instead a relational view of space and time. it was part of the achievement of einstein to remove space and time from their privileged position as the " stage " on which the events of the universe are played out, and replace them by a concept of space and time as part of the fabric of the universe, acting and acted upon by matter and energy in a dynamical system. analogously, in " classical " logic one first specifies the language ( syntax and rules of inference ) and then constructs " universes " with this language as the stage - setting. a way to avoid the paradoxes and limitations to which this gives rise is a description in which the language is no longer separate from and prior to the object being described. ( barwise and etchemendy ( 1987 ) use just such a strategy to deal with the liar paradox, although the limitations of logic to abstract objects are not challenged. i comment further on situation semantics below. ) such descriptions would be impredicative - - physicists might call them non - local - - in that the specification of a single object would involve the whole universe or a substantial part of it : that each singular substance expresses the whole universe in its own way, and that in its concept are included all of the experiences belonging to it together with all of their circumstances and the entire sequence of exterior events. ( leibniz 1686, 308 ) mach ' s principle may be regarded as an expression of this in dynamics. in quantum theory, bohr frequently noted the following corollary to, or instance of, complementarity : on the lines of objective description, it is indeed more appropriate to use the word phenomenon to refer only to observations obtained under circumstances whose description includes an account of the whole experimental arrangement. ( bohr 1961, 73 ) this means, in fact, since it is not clear where to draw the line that separates the " whole experimental arrangement " ( and the laws governing it ) from the rest of the world, that the description of a phenomenon implicitly includes the whole universe. such impredicativity has the consequence that one cannot construct from scratch models of a universe consisting of " singular substances ". this would be considered by logicians a drawback of impredicativity ;


implicitly includes the whole universe. such impredicativity has the consequence that one cannot construct from scratch models of a universe consisting of " singular substances ". this would be considered by logicians a drawback of impredicativity ; but in the context of the problem of smolin, it may be an advantage that not only are there no obvious models of the system which are describable from outside, but perhaps such models are in principle not possible. situation semantics ( barwise and perry 1983 ; barwise 1989 ) is a different kind of attempt to address the problem of the impossibility of describing everything in the context of the analysis of natural language. the approach of viewing utterances and inferences as situated activities differs from the present one in that it is epistemological rather than ontological. it " shifts attention from truth preservation to information extraction and information processing " ( barwise 1989, xiv ; emphases in original ). furthermore, its syntax presupposes the existence and discreteness - - the abstractness - - of objects. ian hacking ( 1972, 148 ), discussing leibniz ' s notion of individual substance, makes an important point : which bundles [ of qualities ] are substances? only those bundles that are active, in the sense of having laws of their own. laws provide the active principle of unity. there is a tendency in much analytic philosophy to conceive things as given, and then to speculate on what laws they enter into. on the contrary, things are in the first instance recognized by regularities. ( emphasis in original ) thus a logic of natural objects will put priority on addressing the question : what makes an individual an individual? as hacking points out, leibniz shares with berkeley the view that substances are bundles of qualities ; the important question, as in the quote above, is the converse. with the principle that each object ( or singular substance, or thing, or individual, or phenomenon ) irreducibly reflects its entire surroundings, we have come to a fusion of the first two principles mooted : the indescribability of the individual and of the universe. in combination with either of these, it implies the other. in leibniz ' s case, this third principle is a consequence of the principle of reason ( or of " predicate - in - notion " ) - - as is another principle, that no two individuals are exactly alike. the identity of indiscernibles has not received attention here but is indeed logically


of the principle of reason ( or of " predicate - in - notion " ) - - as is another principle, that no two individuals are exactly alike. the identity of indiscernibles has not received attention here but is indeed logically linked to the principles adduced above. the principle of reason does not stand up to scrutiny in the light of contemporary logic, but some of its consequences may be recast for our use. in the novum organum bacon ( 1620, 41 ) criticizes aristotelian logic thus : the syllogism is not applied to the first principles of sciences, and is applied in vain to intermediate axioms, being no match for the subtlety of nature. it commands assent therefore to the proposition, but does not take hold of the thing. a modern logic of natural objects would aim to take hold of the thing, aiming to secure sound principles for reasoning with individuals without need of leibniz ' s metaphysical starting point. 1. i am grateful to john wahlert for elucidating this example for me. aczel, peter ( 1988 ). non - well - founded sets, csli lecture notes 14, stanford. azzouni, jody ( 1994 ). metaphysical myths, mathematical practice : the ontology and epistemology of the exact sciences, cambridge university press. bacon, francis ( 1620 ). the new organon, ed. fulton h. anderson, the library of liberal arts, bobbs - merrill, 1960. barwise, jon ( 1989 ). the situation in logic, csli lecture notes 17, stanford. barwise, jon and john etchemendy ( 1987 ). the liar, oxford university press. barwise, jon and lawrence moss ( 1998 ). vicious circles. csli lecture notes 60. barwise, jon and j. perry ( 1983 ). situations and attitudes, mit press, cambridge, mass. and london. bertalanffy, ludwig von ( 1968 ). general systems theory, george braziller, new york. boffa, m ( 1969 ). sur la theorie des ensembles sans axiome de fondement, bull soc. math. belg. 31, 16 - 56. boffa, m ( 1972 ). l ' axiome de paire dans le systeme de zermelo, arch. math. logik grundlagenforsch. 15, 97 - 98. bohr, niels ( 1961 ). atomic physics and human knowledge, science editions,


, ian ( 1972 ). individual substance, in : leibniz : a collection of critical essays, ed. harry g. frankfurt, anchor books. hartmann, nicolai ( 1949 ). new ways of ontology, greenwood press, henry regnery co., 1975. translation of neue wege der ontologie, w. kohlhammer, stuttgart. holsinger, kent e. ( 1984 ). the nature of biological species, philosophy of science 51, 293 - 307. hull, david l. ( 1978 ). a matter of individuality, philosophy of science 45, 335 - 360. kanamori, akihiro ( 1996 ). the mathematical development of set theory from cantor to cohen, bull. symbolic logic 2 ( 1 ), 1 - 71. kim, jaegwon ( 1978 ). supervenience and nomological incommensurables, american philosophical quarterly, 15 ( 2 ), 149 - 156. leibniz, gottfried wilhelm ( 1686 ). discourse on metaphysivs, in philosophical papers and letters, trans. leroy e. loemker, 2nd ed., d. reidel, 1969. levins, richard and richard lewontin ( 1980 ). dialectics and reduction in ecology, synthese 43, 47 - 78. linde, andrei ( 1990 ). inflation and quantum cosmology, academic press. mayr, ernst ( 1976 ). evolution and the diversity of life, belknap press, harvard university press. mesarovic, m. d. and yasuhiko takahara ( 1975 ). general systems theory : mathematical foundations, academic press. mirimanoff, d. ( 1917 ). remarques sur la theorie des ensembles et les antinomies cantoriennes, i, l ' enseignement math. 19, 209 - 217. pagels, heinz r. ( 1982 ). the cosmic code : quantum physics as the language of nature, simon & schuster, new york. russell, bertrand, and alfred north whitehead ( 1910 ). principia mathematica, cambridge university press, 1962. skolem, thoralf ( 1922 ). some remarks on axiomatized set theory, translated in van heijenoort ( 1967, 290 - 301 ). smolin, lee ( 1997 ). the life of the cosmos, oxford university press. sober, elliott ( 1984 ). sets, species, and evolution : comments on philip kitcher '


| foundation of quantum theory | the following well - known experiments serve as a motivation for studying quantum theory. the experimental results cannot be explained using ideas from classical physics. | 1. blackbody radiation | | 2. photoelectric effect | | 3. compton effect | it is well - known that when a body is heated it emits electromagnetic radiation. for example, if a piece of iron is heated to a few hundred degrees, it gives off e. m. radiation which is predominantly in the infra - red region. when the temperature is raised to 1000c it will begin to glow with reddish color which means that the radiation emitted by it is in the visible red region having wavelengths shorter than in the previous case. if heated further it will become white - hot and the radiation emitted is shifted towards the still shorter wave - length blue color in the visible spectrum. thus the nature of the radiation depends on the temperature of the emitter. a heated body not only emits radiation but it also absorbs a part of radiation falling on it. if a body absorbs all the radiant energy falling on it, then its absorptive power is unity. such a body is called a black body. an ideal blackbody is realized in practice by heating to any desired temperature a hollow enclosure ( cavity ) and with a very small orifice. the inner surface is coated with lamp - black. thus radiation entering the cavity through the orifice is incident on its blackened inner surface and is partly absorbed and partly reflected. the reflected component is again incident at another point on the inner surface and gets partly absorbed and partly reflected. this process of absorption and reflection continues until the incident beam is totally absorbed by the body. the inner walls of the heated cavity also emit radiation, a part of which can come out through the orifice. this radiation has the characteristics of blackbody radiation - the spectrum of which can be analyzed by an infra - red spectrometer. experimental results show that the blackbody radiation has a continuous spectrum ( shown in the graph ). the intensity of the emitted radiation el is plotted as a function of the wavelength l for different temperatures. the wavelength of the emitted radiation ranges continuously from zero to infinity. el increases with increasing temperature for all wavelengths. it has very low values for both very short and very long wavelengths and has a maximum in between at some wavelength lmax. lmax depends on the temperature of the blackbody and decreases with increasing temperature. the shift in the peak of the intensity distribution curve obeys an empirical relationship known as


short and very long wavelengths and has a maximum in between at some wavelength lmax. lmax depends on the temperature of the blackbody and decreases with increasing temperature. the shift in the peak of the intensity distribution curve obeys an empirical relationship known as wien ' s displacement law : lmax t = constant. the total power radiated per unit area of a blackbody can be derived from thermodynamics. this is known as stefan - boltzmann law which can be expressed mathematically as : e = s t4, where s = 5. 67 x 10 - 8 w m - 2 k - 4 is known as stefan ' s constant. note that the total power e radiated is obtained by integrating el over all wavelengths. w. wien proposed an empirical relationship between el with l for a given temperature t : el ( t ) = a exp ( - b / lt ) / l5, where the constants a and b are chosen arbitrarily so as to fit the experimental energy distribution curves. but it was later found that the experimental data don ' t follow wien ' s empirical relation at larger wavelengths [ see fig. below ]. wien ' s theory of intensity of radiation was based only on arguments from thermodynamics not on any plausible model. considering the radiation system as composed of a bunch of harmonic oscillators rayleigh and jeans derived ( using thermodynamics ) an expression for the emitted radiation el : el = ( c / 4 ) ( 8pkbt / l4 ). ' kb ' is the boltzman constant ( kb = 1. 345 x 10 - 23 j / k ). the above expression agrees well with the experimental results at long wavelengths but drastically fails at shorter wavelengths. in the limit l - > 0, el - > infinity from the expression above, but in the experiments el - > 0, as l - > 0. this serious disagreement between theory and experiment indicates the limitations of classical mechanics. max planck later derived an expression for the emitted radiation using quantum mechanics. he made a bold new postulate that an oscillator can have only energies which are discrete, i. e., an integral multiple of a finite quantum of energy hf where h is planck ' s constant ( h = 6. 55 x 10 - 34 j. s ) and f is the frequency of the oscillator. thus the energy of the oscillator is, e = nhf, where n is an integer or zero. planck further assumed that


. 55 x 10 - 34 j. s ) and f is the frequency of the oscillator. thus the energy of the oscillator is, e = nhf, where n is an integer or zero. planck further assumed that the change in energy of the oscillator due to emission or absorption of radiant energy can also take place by a discrete amount hf. since radiation is emitted from the oscillators, and since according to planck, the change in energy of the oscillators can only take discrete values, the energy carried by the emitted radiation, which is called a photon, will be hf, and that is also equal to the loss of energy of the oscillator. again, this is also the energy gain of the oscillator when it absorbs a photon. based on these ideas planck derived the expression for the energy distribution of blackbody radiation : el = ( c / 4 ) ( 8phc / l5 ) ( 1 / [ exp ( hc / lkbt ) - 1 ] ). rayleigh - jean ' s expression and wien ' s displacement law are special cases of planck ' s law of radiation. planck ' s formula for the energy distribution of blackbody radiation agrees well with the experimental results, both for the long wavelengths and the short wavelengths of the energy spectrum. please on the simulation below to see nice interactive demonstration of the physics of blackbody radiation. simulation on blackbody radiation back to top planck ' s postulate regarding the discrete nature of the possible energy states of an oscillator marked a radical departure from the ideas of classical physics. according to the laws of classical mechanics, the energy of an oscillator can vary continuously, depending only on the amplitude of the vibrations - this is in total contrast to planck ' s hypothesis of discrete energy states of an oscillator. photoelectric effect is another classic example which can not be explained with classical physics. einstein was awarded nobel prize for his explanation of the physics of photoelectric effect. the basic experiment of photoelectric effect is simple. it was observed that a metal plate when exposed to ultraviolet radiation became positively charged which showed that it has lost negative charges from its surface. these negatively charged particles were later identified to be electrons ( later named photoelectrons ). this phenomenon is known as photoelectric effect. please out the physics applet below which shows the effect of light on various metals. simulation on photoelectric effect the main results of the


to be electrons ( later named photoelectrons ). this phenomenon is known as photoelectric effect. please out the physics applet below which shows the effect of light on various metals. simulation on photoelectric effect the main results of the experiment can be summarized as follows : on exposure to the incident light, photoelectrons with all possible velocities ranging from 0 upto a maximum vm are emitted from the metal plate. when a positive potential is applied to the collector ( which collects the emitted photoelectrons ), a fraction of the total number emitted is collected by the collector. this fraction increases as the voltage is increased. for potentials above about + 10 volts, all the electrons emitted by the light are collected by the collector which accounts for the saturation of the photoelectric current [ figs. ( a ) and ( b ) below ]. on the other hand, when a negative retarding potential is applied on the collector, the lower energy electrons are unable to reach the collector so that the current gradually decreases with increasing negative potential. finally for a potential - v0 ( known as the stopping potential ), the photoelectrons of all velocities upto the maximum vm are prevented from reaching the collector. at this point, the maximum kinetic energy of the emitted electrons equals the energy required to overcome the effect of the retarding potential - so we can write mvm2 / 2 = ev0. conclusion from the experimental results : ( 1 ) the photoelectric current depends upon the intensity of the light used. it is independent of the wavelength of the light [ see fig. ( a ) above ]. ( 2 ) the photoelectrons are emitted with all possible velocities from 0 upto a maximum vm which is independent of the intensity of the incident light, but depends only on its wavelength ( or frequency ). it is found that if f is the frequency of the light used, then the maximum kinetic energy of the photoelectrons increases linearly with f [ see figs. ( b ) and ( c ) above ]. ( 3 ) photoelectron emission is an instantaneous effect. there is no time gap between the incidence of the light and the emission of the photoelectrons. ( 4 ) the straight line graph showing the variation of the maximum kinetic energy of the emitted electrons with the frequency f of the light intersects the abscissa at some point f0. no photoelectron emission takes


the photoelectrons. ( 4 ) the straight line graph showing the variation of the maximum kinetic energy of the emitted electrons with the frequency f of the light intersects the abscissa at some point f0. no photoelectron emission takes place in the frequency range f < f0. this minimum frequency f0 is known as the threshold frequency. its value depends on the nature of the emitting material [ see fig. ( c ) above ]. breakdown of classical physics : according to classical physics - ( a ) light is an electromagnetic wave - the intensity of light is determined by the amplitudes of these electromagnetic oscillations. when light falls on an electron bound in an atom, it gains energy from the oscillating electric field. larger the amplitude of oscillations, larger is the energy gained by the emitted electron - thus energy of the emitted electrons should depend on the intensity of the incident light. this is in contrast to what has been observed in experiment ( point 2 above ). ( b ) according to the electromagnetic theory, the velocity of the emitted electrons should not depend on the frequency of the incident light. whatever may be the frequency of the incident light, the electron would be emitted if it gets sufficient time to collect the necessary energy for emission. so the photoelectric emission is not an instantaneous effect. these are in contrary to points 3 and 4 above. ( c ) finally, the incident electromagnetic wave acts equally on all the electrons of the metal surface. there is no reason why only some electrons will be able to collect the necessary energy for emission from the incident waves. given sufficient time, all electrons should be able to collect the energy necessary for emission. so there is no reason why the photoelectric current should depend upon the intensity of the incident light. however, this is again in contrary to the observed facts ( point 1 above ). einstein ' s light quantum hypothesis and photoelectric equation : we have seen from above that the maximum kinetic energy of the emitted photoelectrons increases linearly with the frequency of the incident light. in terms of equation we have mvm2 / 2 = ev0 = af - w where a and w are constants. w is known as the work function of the emitting material. the constant a was determined experimentally and is found to be equal to the planck ' s constant h. we can then rewrite the above equation as - mvm2 / 2 = ev0 = hf - w. for the special value of f =


a was determined experimentally and is found to be equal to the planck ' s constant h. we can then rewrite the above equation as - mvm2 / 2 = ev0 = hf - w. for the special value of f = f0 = w / h, the k. e. of the emitted photoelectrons becomes zero. so there will be no photoelectron emission if f < f0. f0 is the threshold frequency. the equation, mvm2 / 2 = ev0 = hf - hf0 is known as the famous einstein ' s photoelectric equation. einstein used the quantum hypothesis of planck to explain the photoelectric effect. he postulated that light is emitted from a source in the form of energy packets of the amount hf known as the light quantum or photon. this is known as einstein ' s light quantum hypothesis. when a photon of energy hf falls on an electron bound inside an atom, the electron absorbs the energy hf and is emitted from the atom provided that hf is greater than the energy of binding of the electron in the atom which is equal to the work function w of the metal. the surplus of energy ( hf - w ) is taken away by the electron as its kinetic energy. obviously if hf < w, i. e. f < f0, no photoelectric emission can take place. this explains the existence of the threshold frequency. furthermore, according to einstein ' s theory, larger the number of photons falling on the metal, greater is the probability of their encounter with the atomic electrons and hence greater is the photoelectric current. so the increase of photoelectric current with the increasing light intensity can be easily explained. finally, as soon as the photon of energy hf > w falls on an electron, the latter absorbs it and is emitted instantaneously. note that einstein ' s light quantum hypothesis postulates the corpuscular nature of light in contrast to the wave nature. we will talk about this wave - particle duality later on in this course. back to top the discovery of compton scattering of x - rays provides direct support that light consists of pointlike quanta of energy called photons. a schematic diagram of the apparatus used by compton is shown in the figure below. a graphite target was bombarded with monochromatic x - rays and the wavelength of the scattered radiation was measured with a rotating crystal spectrometer. the intensity was determined by a movable ionization chamber


compton is shown in the figure below. a graphite target was bombarded with monochromatic x - rays and the wavelength of the scattered radiation was measured with a rotating crystal spectrometer. the intensity was determined by a movable ionization chamber that generated a current proportional to the x - ray intensity. compton measured the dependence of scattered x - ray intensity on wavelength at three different scattering angles of 45o, 90o, and 135o. the experimental intensity vs. wavelength plots observed by compton for the above three scattering angles ( see fig. below ) show two peaks, one at the wavelength l of the incident x - rays and the other at a longer wavelength l '. the functional dependence of l ' on the scattering angle and l was predicted by compton to be : l ' - l = ( h / mec ) [ 1 - cosq ] = l0 [ 1 - cosq ]. the factor l0 = h / mec, also known as compton wavelength can be calculated to be equal to 0. 00243 nm. the physics of compton effect : to explain his observations compton assumed that light consists of photons each of which carries an energy hf and a momentum hf / c ( as p = e / c = hf / c ). when such a photon strikes a free electron the electron gets some momentum ( pe ) and kinetic energy ( te ) due to the collision, as a result of which the momentum and energy of the photon are reduced. considering energy and momentum conservation ( for the detail derivation please here ) one can derive the change in wavelength due to compton scattering : l ' - l = ( h / mec ) [ 1 - cosq ]. note that the result is independent of the scattering material and depends only on the angle of scattering. the appearance of the peak at the longer wavelength in the intensity vs. wavelength curve is due to compton scattering from the electron which may be considered free, since its energy of binding in the atom is small compared to the energy hf of the photon. the appearance of the other peak at the wavelength of the incident radiation is due to scattering from a bound electron. in this case the recoil momentum is taken up by the entire atom, which being much heavier compared to the electron, produces negligible wavelength shift. compton effect gives conclusive evidence in support of the corpuscular character of electromagnetic radiation. please out the simulation below which shows compton scattering. simulation on compton scattering back to top © kingshuk majumdar ( 2000 )


produce hay to make a profit whether a rancher grows hay to feed his livestock or someone else ’ s, the enterprise isn ’ t worthwhile unless it makes money. surprisingly, many hay producers have no idea how much it costs them to produce a crop. university of kentucky extension hay marketing specialist tom keene says essentially, producers have two ways to market : as cash or as hay for their own livestock enterprise. regardless of which path a producer takes, the hay budget must be unto itself. “ there ’ s only one way you can know whether you ’ re making money : you have to go through the numbers, ” keene says. after a producer runs through the cost of producing hay, he or she needs to figure one more number : storage losses. • hay production needs to be run as a separate business. • know hay costs, whether selling to the cash market or your own livestock. • set price based on production costs and local market. “ the numbers get a lot worse, ” keene says. “ and they get worse quick. ” that ’ s only one of the reasons growing hay for profit is different from any other commodity. another is that “ no bale of hay is quite the same. ” what that means to producers is they must decide which market their hay fits. the dairy market wants large round bales ; demands a test ; looks for 20 % crude protein, 30 % acid detergent fiber and 40 % neutral detergent fiber ; and measures feed performance by milk production. dairy producers prefer alfalfa. the horse market wants small square bales, doesn ’ t necessarily ask for a test, and buys on sensory perception. those who buy hay for their horses have no way to measure feed performance in their high - value animals. they like hay that smells fresh and looks green. “ that hay absolutely, positively must be clean. no mold, dust, weeds, foreign matter, blister beetles, ” keene says. the beef market wants large round bales, measures performance on pounds gained and has varying quality needs. “ we throw anything out at them, ” keene says. most of the hay grown for the beef market is grown by producers for themselves. “ most of you are probably selling hay to your own operation, ” keene tells a group of cattle producers. “ i hope you ’ re keeping track of the numbers. ” other markets include — but certainly aren ’ t limited to — sheep, mulch, goats, llamas, emu, zoos, nurseries


a group of cattle producers. “ i hope you ’ re keeping track of the numbers. ” other markets include — but certainly aren ’ t limited to — sheep, mulch, goats, llamas, emu, zoos, nurseries, feed stores, rabbits, gerbils, medical research and, most recently, energy. regardless of the market, keene says, growers need to know the cost of producing the hay and the current prices in their market area so they can set a price that moves the hay and brings a profit. current prices can be found by looking at usda hay prices on the web, asking neighbors and extension agents, or even checking the sales ads. “ that ’ s going to give you an idea of what your hay will bring in the market, ” keene says. “ only you know what it ’ s worth. ” once that price is set, keene says, collect the money on delivery. “ if you sell somebody a car or pickup truck and they can ’ t make the payments, you can go back and get that vehicle. you can ’ t go back and get your hay, ” keene says. “ it ’ s gone. ” pay attention : alabama cattle producer eric smith keeps track of a forage ’ s cost and income as though it were a row crop. this article published in the march, 2010 edition of southern farmer. all rights reserved. copyright farm progress cos. 2010.


bivalves in time and space ( bits ) : clams as tools to understand macroevolution 2011 reu project : this study is part of a collaborative effort ( see also www. bivatol. org / bits / ) to develop bivalves as a model clade for macroevolutionary studies. by integrating molecular, morphological and paleontological datasets, bits aims to test methods of molecular clock dating, ancestral state reconstruction and historical biogeography, as well as to detect spatial and temporal trends in evolution. bits researchers at the field museum concentrate on the morphological and paleontological components of the project, investigating the evolution of numerous shell and anatomical features in two of the commonest bivalve lineages - venus clams and cockles. research methods and techniques : reu participants in the project will receive an introduction to bivalve morphology and systematics, with particular focus on shell characters - i. e., those that preserve well in fossils. they will prepare specimens, document diagnostic characters with optical and scanning electron microscopy, build and analyze phylogenetic trees, and gain experience with relevant literature research and collection management techniques. curator / advisors : dr. rudiger bieler, zoology / invertebrates, in collaboration with postdoctoral fellow dr. andre sartori. reu intern : katherine anderson ecology and evolutionary biology major university of michigan, ann arbor symposium presentation title : diversity of venus clams : building an online resource for species identification symposium presentation abstract : venerids, commonly known as venus clams, are the most diverse family of marine bivalves, with over 500 extant species. they are found on every continent except antarctica, and many are edible, commercially collected and cultured, comprising an important food source worldwide. despite their prevalence and economic importance, there is still no freely accessible, online catalogue available to aid in recognition of venerid species. species identification is crucial not only for economic reasons, but also for conserving biodiversity and ensuring accuracy in scientific studies. an online catalogue consisting of individual species pages with detailed morphological descriptions and high quality photographs is being built in order to provide a resource that is both complete and available for anyone to use. specimens from the collections of the field museum of natural history were identified to species level using primary and secondary literature. following identification, the morphology of the shell of each species was thoroughly described based on characteristics of all specimens available. descriptions include details of overall shape and coloration, as well as features important for bivalve taxonomy, such as the morphology of the hinge


following identification, the morphology of the shell of each species was thoroughly described based on characteristics of all specimens available. descriptions include details of overall shape and coloration, as well as features important for bivalve taxonomy, such as the morphology of the hinge teeth, lunule, escutcheon and ligament. in order to aid in identification, differences among similar species that may be commonly confused were also noted on each species page. high quality photographs of the dorsal view, external and internal views of one valve, and the hinge plates of both valves were taken of a representative specimen of each species. species pages were published on ebivalvia, a collaborative database for information about bivalves, which shares its contents with the encyclopedia of life. in addition to species pages, genus pages were also created containing descriptions of characteristics shared by all species within a genus. at this time, over 100 species of venerids have been described and photographed. the species pages may become more comprehensive in the future, as information such as habitat and distribution is appended. the online catalogue not only documents the diversity of venus clams, but also provides an accurate and accessible resource for species identification that can be utilized by researchers, students and shell collectors, as well as conservation agencies and fisheries.


robert a. pritzker assistant curator of meteoritics and polar studies philipp heck and co - authors from the max - planck - institute for chemistry in germany had their paper on the first isotopic analysis of sulfur - rich comet dust published in the april issue of the journal meteoritics & planetary science. the dust was captured during a flyby of comet wild 2 by nasa ’ s stardust mission and returned to earth. the robert a. pritzker center for meteoritics and polar studies is proud to announce the newest addition to the meteorite collection. the newly named meteorite thika, recently classified as a l6 ordinary chondrite, was donated to the center by collections and research committee member terry boudreaux in mid - september. field museum researchers at the robert a. pritzker center for meteoritics and polar studies have received a second target foil from the interstellar dust collector onboard nasa ' s stardust mission - that returned the first solid extraterrestrial material to earth from beyond the moon. we announce a call for abstracts for the session p15 “ laboratory analysis of extraterrestrial dust returned to earth ” at the fall meeting 2011 of the american geophysical union ( agu ), december 5 - 9, 2011 san francisco, california, usa. collections & research committee member terry boudreaux donated a very unusual meteorite specimen to the field museum ’ s robert a. pritzker center for meteoritics and polar studies. the meteorite is named nwa 5492 after northwest africa where it was found. its petrology and chemical composition are very different compared to other meteorites and it cannot be classified with the existing scheme. about 470 million years ago – in a time period called ordovician – the parent asteroid of one of the l chondrites, one of the most common meteorite types, was disrupted in a collision with another body. this event led to a subsequent bombardment of earth with collisional debris for at least 10 million years. this finding is reported in a recent study in earth and planetary science letters by field museum scientists dr. birger schmitz ( research associate ), robert a. pritzker assistant curator of meteoritics and polar studies dr. philipp heck, and an international team of coauthors. right after the mifflin meteorite fell in sw wisconsin in april 2010 the robert a. pritzker assistant curator of meteoritics and polar studies dr. philipp r. heck coordinated an international study to determine the


on this day - 22 may 1918 theatre definitions : western front comprises the franco - german - belgian front and any military action in great britain, switzerland, scandinavia and holland. eastern front comprises the german - russian, austro - russian and austro - romanian fronts. southern front comprises the austro - italian and balkan ( including bulgaro - romanian ) fronts, and dardanelles. asiatic and egyptian theatres comprises egypt, tripoli, the sudan, asia minor ( including transcaucasia ), arabia, mesopotamia, syria, persia, afghanistan, turkestan, china, india, etc. naval and overseas operations comprises operations on the seas ( except where carried out in combination with troops on land ) and in colonial and overseas theatres, america, etc. political, etc. comprises political and internal events in all countries, including notes, speeches, diplomatic, financial, economic and domestic matters. source : chronology of the war ( 1914 - 18, london ; copyright expired ) liege and metz railways bombed by british airmen ; mannheim again attacked. raid attempted on paris by about 30 german machines, but only one reaches capital. increased artillery fighting along piave ; an attack at capo sile bridgehead repulsed. allied airmen active. naval and overseas operations air - raids on zeebrugge ; a german destroyer sunk in harbour. in east africa british engage enemy between nanungu and mahua ; capture guns and ammunition, drive germans westward. u. s. a. sedition bill passed, and 300, 000, 000 voted for ordnance.


photo by della chen at the crux of most debates on the future of food production is one often - contentious point of comparison : the viability of organic versus conventional farming methods. on one hand, our growing populations require an affordable, nourishing, and immediately available food supply — a demand that many point to as a reason to favor conventional, higher - yield methods. on the other, organic farming advocates argue that sustainable practices will have a further - reaching, more positive impact on local economies, communities, and the future at large than conventional methods can even begin to offer. entering the fray is writer sam fromartz, who recently posted a response on his blog to an essay by journalist / author marc gunther. sam ' s piece offers an even - handed take on why number - crunching crop yields doesn ' t paint a broad enough picture to ultimately answer the question of organic versus conventional : " the problem with this argument is not that the yield calculations are wrong. the problem is that yield studies are inappropriate by themselves in measuring what ' s ' sustainable, ' in determining what might ' feed the world, ' and which methods actually end up using more land in a particular situation. that ’ s because farming does not occur in a vacuum where yield is the sole measure of success. " he goes on to speak candidly explore the limitations of counting solely on yield calucations as indicators of success, specifically in regards to environmental impact and famer livelihood. he also highlights alternative methods to getting the most out of a single crop, like addressing pre - and post - harvest food waste. an illuminating read! sign up now and get $ 10 when we open.


| did you know? | | acidic drinks such as soda, energy drinks, and water with lemon erode the surface of the tooth, called enamel, which can lead to decay. instead of letting acid from drinks sit on your teeth, rinse your mouth with plain water. | if eyes are the window to the soul, then a smile offers a peek at the pancreas. just as diabetes can affect your kidneys, feet, heart, and eyes, it plays a role in your oral health, too. research in this area is young, but studies show that the disease affects the mouth by targeting the gums, increasing decay, and slowing healing. probably the greatest impact diabetes has on the mouth is in upping the severity of periodontal disease. this serious gum infection can destroy the tissues and bones that keep the teeth in place and may result in tooth loss. some signs include red, swollen, and / or bleeding gums, loose or sensitive teeth, and persistent bad breath. “ there is very good evidence that diabetes is a risk factor for periodontal disease, both in extent and severity, ” says ira lamster, dds, professor of dental medicine and dean emeritus of the college of dental medicine at columbia university medical center. | good to know | | though uncontrolled diabetes can result in oral health problems, a single episode of high or low blood glucose won ’ t harm your teeth. | though gum disease is a direct result of bacteria, in the form of plaque buildup on teeth and especially below the gum line, there ’ s no difference between the bacteria in your mouth and those in the mouth of someone without diabetes. instead, lamster says, gum disease is worse in people with diabetes because of a greater inflammatory response to the bacteria. but the link between diabetes and gum disease isn ’ t a one - way street. “ if a person has moderately advanced to advanced periodontal disease and they have diabetes, their metabolic control will be worse, ” lamster says. in fact, some research suggests early signs of gum disease may be an indicator of prediabetes and type 2 diabetes. a 2011 study in the journal of dental research found that dentists could identify 73 percent of people with undiagnosed diabetes in part because of the presence of periodontal disease. that suggests routine cleanings could help screen for the disease. | how to floss | | 1. with floss between two teeth, curve the floss into a c shape so it ’ s snu


the presence of periodontal disease. that suggests routine cleanings could help screen for the disease. | how to floss | | 1. with floss between two teeth, curve the floss into a c shape so it ’ s snug against one tooth. | 2. rub floss up and down against the tooth and into the space between the tooth and gum. 3. repeat with the other tooth before moving on to the next gap between teeth. the good news is that if you treat your gum disease, you may see improvements in your glucose control. yet, according to the american diabetes association ’ s 2012 standards of medical care in diabetes, the quality of studies on the topic is up for debate, so how much your a1c may improve is uncertain. depending on the extent of the gum disease, a dentist may do a deep cleaning, prescribe medications, or perform surgery. dry mouth is a common problem for people with diabetes, and though it may be a result of aging or medications, lamster says it could be a complication of the disease. the autonomic nervous system controls salivary gland function, so problems with creating saliva are a form of diabetic neuropathy. ( note that nerve damage doesn ’ t cause any other problems in the mouth, not even tooth sensitivities or pain, which may be a result of gum disease, tooth decay, grinding teeth, tooth whitening, and so on. ) lacking spit may not sound like a big deal, but the condition does more than make your throat dry and lips chapped. “ saliva is one of our body ’ s defense systems, ” says thomas oates, dmd, phd, assistant dean of clinical research and vice chair of the department of periodontics at the university of texas health science center at san antonio dental school. “ it protects the gums from getting infected. ” less saliva means less protection for the teeth against acid and plaque, which leads to tooth decay. this is compounded if you eat often : “ there ’ s a lot of research that suggests frequency of eating can be a problem, ” oates says, though he notes that there ’ s no research directly linking diabetes to an increased risk of cavities. eating glucose or candy to treat lows won ’ t necessarily up your cavity count, but eating those foods often can. ( if you ’ re eating frequently to treat low blood glucose, however, talk to your doctor about ways to adjust your treatment and limit the number of lows.


##s won ’ t necessarily up your cavity count, but eating those foods often can. ( if you ’ re eating frequently to treat low blood glucose, however, talk to your doctor about ways to adjust your treatment and limit the number of lows. ) | experts recommend brushing for at least two minutes, concentrating on each individual tooth, including the surrounding gum. | people with diabetes are more likely to have root decay, too. receding gums, a problem that happens with age and gum disease, can expose a tooth ’ s root and leave an opening for decay. to stimulate the cleansing effects of saliva at times when you can ’ t brush or rinse your mouth with water, try chewing sugar - free gum or candy. and take healthy - mouth steps to prevent decay. for starters, get rid of plaque by brushing twice a day with a fluoride toothpaste, floss daily, and get regular teeth cleanings ( usually every six months ), when a dental hygienist will scrape plaque from your teeth. | q & a | | do i have to brush each time i treat a low with glucose? | nope, but it ’ s smart to rinse your mouth with water and / or chew sugar - free gum or candy. doing so will stimulate the saliva that protects teeth. it makes sense that if diabetes slows wound healing in foot ulcers, for instance, the same would be true for the mouth. but oral wounds typically don ’ t face the same problems as elsewhere in the body because the mouth has lots of blood flow and possibly because saliva helps fight infection. the same isn ’ t true of healing from dental surgery. for the past six years, oates has studied the effects of dental implants in people with diabetes and has found that they have delayed healing of the bone around the implant compared with people without diabetes. though the link between slow healing from dental surgery and diabetes is still being investigated, you can better your chances of a quick recovery by making sure your blood glucose is well controlled. in the end, you play a large role in preventing potential oral complications of diabetes, so take the time to keep your glucose in line and your mouth minty fresh.


the aslan base their calendar and timekeeping units on the period of kusyu ( the aslan homeworld ) around tyeyo, its star. the aslan year is the ftahea, 212. 2 eakhau ( aslan days ) long. a is 319. 98 standard days in length ; an eakhau is 36 hours long. each eakhau has a unique name ; for convenience they are numbered from one to 212 and referred to by number. to every fifth ftahea, a 213th eakhau is added to keep the calendar in sync with kusyu. the aslan also divide their ftahea into three raohfokh ( seasons ) : aihros, tralrea, and ktaho. aihros ( beginning ) is the equivalent of spring : the mating season for many animals and the time when annual plant life grows from see. tralrea ( growth ) is the long season of mild weather on kusyu ; it is the growing season ( although in this sense it referes to the growing of herd animals ) and lasts 100 eakheau. ktaho ( harvest ) is the hunting season ; it is short ( only 30 eakheau ) and a traditional time of aslan hunts. the aslan calendar began counting time when the first tlaukhu was established. the data of 3658 corresponds to the imperial date of 1120. an aslan date is stated in the same format as an imperial date. a three - digit eakhau number is followed by a hyphen and a four - digit ftahea number. for proper identification in the imperium, the date is usually followed by the word aslan. for example, 201 - 3644 aslan is the 201st day of the 3644th year of the aslan calender ; it is equivalent to 000 - 0000. the planet kusyu has only minimal axial tilt and orbital eccentricity. there is little inthe way of astronomical cause for seasons on the world, and the aslan calendar has no seasons because there is so little in its climate to cause them.


air force project could ' transform ' supercomputing recent advances in supercomputing haven ’ t just been about speed, but in developing more energy - efficient architectures, as the energy department has shown with sequoia at lawrence livermore national laboratory and work on titan at oak ridge national laboratory. the air force is heading down this path too, recently awarding a contract to wu feng, associate professor of computer science in the college of engineering at virginia tech, to speed up simulations of its unmanned micro air vehicles ( mavs ). the tiny aircraft, as small as five inches, with insect - sized models expected in the future, can be used in a variety of military and hazardous conditions. feng, a proponent of green supercomputing, plans to carry out the project with an approach to multi - and many - core parallel computing that he said will “ transform supercomputing, ” according to a virginia tech announcement. the air force project will make use of accelerator - based supercomputers such as hokiespeed, which feng designed and built in 2011 for a mere ( in supercomputing terms ) $ 1. 4 million national science foundation grant. virginia tech ' s wu feng on hokiespeed via vimeo the approach to mav simulations — conducted under a contract with a maximum of $ 6 million over five years — is a multidisciplinary effort, involving aerospace and mechanical engineers, mathematicians and computer scientists from virginia tech and north carolina state university, who by combining advances in math, algorithms and engineering will develop computational fluid dynamic codes and supporting hardware and software, virginia tech said. researchers expect to “ achieve substantial speed - up over current simulations and provide significantly better utilization of the underlying and co - designed hardware - software of a supercomputer, ” feng said. improving performance through parallel hardware and co - designed software is an emerging field, he said. “ furthermore, coupling hardware - software co - design with advances in algorithmic innovation offers the promise of multiplicative speed - ups, ” he said. as supercomputing has gotten steadily more powerful, the amount of energy the machines draw has become a concern. that ’ s one reason feng and kirk cameron of the virginia tech college of engineering started the green500, which ranks supercomputers, in essence, according to how much mileage they get out of the power they use. feng ’ s work on efficient computing dates to when he worked at los alamos national laboratory, where he built a 240 - node cluster


| home > news & policies > proclamation archives | for immediate release office of the press secretary april 18, 2001 national park week, 2001 by the president of the united states of america the united states boasts an incredible wealth of natural beauty. from rugged coastlines and thick forests to arid deserts and canyons, our diverse landscapes represent a treasured heritage of which all americans can be proud. our country ' s commitment to the conservation of its open spaces runs deep. the nation founded yellowstone national park in 1872 and thereby generated renewed appreciation for the great outdoors among americans. our country ' s actions inspired other countries to follow suit by establishing their own national parks or equivalent preserves. since the establishment of the national park service in 1916, our national parks have grown to occupy a special place in the hearts of the american people. as responsible stewards, we must leave them in good condition for those who follow us. by providing additional resources for their preservation and maintenance, we can prevent the deterioration in facilities and infrastructure that threatens their future well - being. national parks are a testament to the natural wonders of our mountains, valleys, rivers, and streams. they remind us to take a break from the busy pace of modern society to experience the simpler pleasures of life and provide unique opportunities for personal recreation. whether camping in yosemite national park or boating along apostle islands national lakeshore, people of all ages can take in spectacular scenery and enjoy a relaxing time with family and friends. the national park service also serves an educational purpose, honoring our heroes and preserving important historical landmarks. by visiting the frederick douglass national historic site, the immigration station on ellis island or many other significant sites in our national parks, americans gain a deeper understanding of our national story and the extraordinary people and events that paved the way for our development and progress. national park week pays tribute to the importance of our national parks and recognizes the dedicated men and women entrusted with their care. the observance also calls attention to the need to reinvest in these national treasures by providing for their sound stewardship in the years to come. as timeless and majestic reminders of our outdoor heritage, america ' s national parks add immensely to our quality of life and represent a wonderful legacy that must be passed on to future generations. now, therefore, i, george w. bush, president of the united states of america, by virtue of the authority vested in me by the constitution and laws of the united states of america, do hereby proclaim april 23 through april 29, 2001, as national park week. i encourage


for plug - in car and battery makers, there ’ s a lesson in the obama administration ’ s recent decision to pull funding for research of hydrogen fuel cells for vehicles : don ’ t rely too heavily on the dole for too long. hydrogen fuel cell vehicles, you may recall, formed a cornerstone of what bush administration officials envisioned as a hydrogen economy. these days, many policymakers and silicon valley entrepreneurs alike are pitching the idea of a clean energy economy, in which we get around in hybrid and electric vehicles that tap renewable energy from a smart grid, rather than the long - promised hydrogen cars. as doe chief steven chu explained in a briefing on the agency ’ s budget proposal, “ we asked ourselves, ‘ is it likely in the next 10 or 15, 20 years that we will convert to a hydrogen car economy? ’ the answer, we felt, was ‘ no. ’ ” based on that conclusion, the doe decided to cut $ 100 million from its hydrogen fuel cell program for 2010 and start dedicating the research initiative to “ fuel cell technologies ” for buildings and other applications, with funding cut down to $ 68 million. ( separately, the agency awarded $ 41. 9 million last month to 12 companies working on portable fuel cells for electronics, and larger fuel cells for both backup power and vehicles. ) in a doe report earlier this year, the agency found that fuel cell costs are still too high and durability too low for the auto industry to meet the goal set out in the energy policy act of 2005 of 100, 000 hydrogen fuel cell - powered vehicles by 2010. the u. s. fuel cell industry is taking the cut as a sign that its energy will be better spent influencing congress than the department of energy. “ we aren ’ t giving up on dr. chu, ” u. s. fuel cell council executive director robert rose told the new york times wheels blog. while the doe has been short - staffed, he said, “ congress will look carefully at this. ” but truth be told, a careful look would find an investment of some $ 1. 2 billion over four years for development of an expensive, far - off technology and zero viable hydrogen vehicles on the market and few stations in the ground ( only about 120 nationwide ) to show for it, especially when it comes to hydrogen production and delivery systems — the core of any hydrogen highway. as the la times up to speed blog notes, chu cited a lack of infrastructure as a reason to pull funding. of course, infrastructure remains one of the big missing pieces for


1 peter 1 : 1 identifies the author of the book of 1 peter as the apostle peter. date of writing : the book of 1 peter was likely written between a. d. 60 and 65. purpose of writing : 1 peter is a letter from peter to the believers who had been dispersed throughout the ancient world and were under intense persecution. if anyone understood persecution, it was peter. he was beaten, threatened, punished and jailed for preaching the word of god. he knew what it took to endure without bitterness, without losing hope and in great faith living an obedient, victorious life. this knowledge of living hope in jesus was the message and christ ' s example was the one to follow. key verses : 1 peter 1 : 3, " praise be to the god and father of our lord jesus christ! in his great mercy he has given us new birth into a living hope through the resurrection of jesus christ from the dead. " 1 peter 2 : 9, " but you are a chosen people, a royal priesthood, a holy nation, a people belonging to god, that you may declare the praises of him who called you out of darkness into his wonderful light. " 1 peter 2 : 24, " he himself bore our sins in his body on the tree, so that we might die to sins and live for righteousness ; by his wounds you have been healed. " 1 peter 5 : 8 - 9, " be self - controlled and alert. your enemy the devil prowls around like a roaring lion looking for someone to devour. resist him, standing firm in the faith, because you know that your brothers throughout the world are undergoing the same kind of sufferings. " brief summary : though this time of persecution was desperate, peter reveals that it was actually a time to rejoice. he says to count it a privilege to suffer for the sake of christ, as their savior suffered for them. this letter makes reference to peter ’ s personal experiences with jesus and his sermons from the book of acts. peter confirms satan as the great enemy of every christian but the assurance of christ ' s future return gives the incentive of hope. connections : peter ’ s familiarity with the old testament law and prophets enabled him to explain various ot passages in light of the life and work of the messiah, jesus christ. in 1 peter 1 : 16, he quotes leviticus 11 : 44 : “ be holy, for i am holy. ” but he prefaces it by explaining that holiness is not achieved by keeping the law, but by the grace


, jesus christ. in 1 peter 1 : 16, he quotes leviticus 11 : 44 : “ be holy, for i am holy. ” but he prefaces it by explaining that holiness is not achieved by keeping the law, but by the grace bestowed upon all who believe in christ ( v. 13 ). further, peter explains the reference to the “ cornerstone ” in isaiah 28 : 16 and psalm 118 : 22 as christ, who was rejected by the jews through their disobedience and unbelief. additional old testament references include the sinless christ ( 1 peter 2 : 22 / isaiah 53 : 9 ) and admonitions to holy living through the power of god which yields blessings ( 1 peter 3 : 10 : 12 ; psalm 34 : 12 - 16 ; 1 peter 5 : 5 ; proverbs 3 : 34 ). practical application : the assurance of eternal life is given to all christians. one way to identify with christ is to share in his suffering. to us that would be to endure insults and slurs from those who call us " goodie two shoes " or " holier than thou. " this is so minor compared to what christ suffered for us on the cross. stand up for what you know and believe is right and rejoice when the world and satan aim to hurt you. © copyright 2002 - 2013 got questions ministries.