Pure Guesswork Research Articles

Comparative Study of Probabilistic Structural Safety Analysis of a Titanium Pressure Vessel

Structural Reliability (Safety Index) is a very important factor of any aerospace product. Until recently, a design was considered robust if all the variables that affected its life had been accounted for and brought under control. The meaning of robustness is shifting. Designer and engineers have traditionally handled variability with safety factors. Some safety factors are derived from observation and analysis, and many cases it used to be pure guesswork. In those cases, the bigger the guess, the bigger the risk, the bigger the safety factor, resulting over designed product. Safety factor cannot, by themselves, guarantee satisfactory performance and they do not provide sufficient information to achieve optimal use of available resources. In this paper pressure vessel made of titanium alloy is considered for structural reliability study. Structural Safety Index is evaluated using uncertainty. Various statistical methods like mean value and moment methods are discussed. Simulation techniques for evaluation of probability of failure are also discussed. Response surface methodology which helps in solving many complex structural problems has been used. Finally, comparative studies have been made for various techniques. These techniques will be useful for Reliability design evaluation.

Tectonic position of marble melanges in the Early Paleozoic accretion-collisional system of the western Pribaikalie

The Early Paleozoic collisional system located in the Olkhon region at the western shores of Lake Baikal resulted from collision of the Siberian paleocontinent and a complex aggregate composed by fragments of a microcontinent, island arcs, back-arc structures and accretionary prisms. The main events were associated with complete manifestation of shear tectogenesis initiated by oblique collision. The current structure includes tectonically displaced components of ancient geodynamic systems that used to have been located dozens and hundreds of kilometres apart. Horizontal amplitudes of tectonic displacement seem to have been quite high; however, numerical data are still lacking to support this conclusion. Information about the structure of the upper crust in the Paleozoic is also lacking as only deep metamorphic rocks (varying from epidote-amphibolite to granulite facies) are currently outcropped. Formations comprising the collisional collage are significantly different in composition and protoliths, and combinations of numerous shifted beds give evidence of a 'bulldozer' effect caused by the collisional shock followed by movements of crushed components of the ocean-continent zone along the margin of the Siberian paleocontinent. As evidenced by the recent cross-section, deep horizons of the Early Paleozoic crust comprise the collisional system between the Siberian craton and the Olkhon composite terrain. A permanent inclusion in the collisional combinations of rocks are unusual synmetamorphic injected bodies of carbonate rocks. Such rocks comprise two groups, marble melanges and crustal carbonate melted rocks. Obviously, carbonate rocks (that composed the original layers and horizons of stratified beds) can become less viscous to a certain degree at some locations during the process of oblique collision and acquire unusual properties and can thus intrude into the surrounding rocks of silicate composition. Such carbonate rocks behave as protrusions or intrusions and contain inclusions of silicate rocks. Formation of marble melanges is a multi-staged process: they occur as early tectonic covers and, more often, accompany shear zones of large lengths, comprise late push-out nappes initiated by shear faults, participate in construction of ring and vortex structures that are generated by shearing in the geological medium of inhomogeneous rheology. In general, the available data give evidence of the fact that formation of synmetamorphic marble melanges is a direct consequence of the oblique collision geodynamics and a sensitive indicator of such a regime. A pure guesswork may suggest that the occurrence of the marble melanges can be associated with a catastrophic loss of viscosity of the carbonate rocks due to a sharp increase of velocities of shear deformations that accompanied the oblique collision.

Measuring Internal Representations from Behavioral and Brain Data

The study of internal knowledge representations is a cornerstone of the research agenda in the interdisciplinary study of cognition. An influential proposal assumes that the brain uses its internal knowledge of the external world to constrain, in a top-down manner, high-dimensional sensory data into a lower-dimensional representation that enables perceptual decisions and other higher-level cognitive functions [1-9]. This proposal relies on a precise formulation of the observer-specific internal knowledge (i.e., the internal representations, or models) that guides reduction of the high-dimensional retinal input onto a low-dimensional code. Here, we directly revealed the content of subjective internal representations by instructing five observers to detect a face in the presence of only white noise, to force a pure top-down, knowledge-based task. We used reverse correlation methods to visualize each observer's internal representation that supports detection of an illusory face. Using reverse correlation again, this time applied to observers' electroencephalogram activity, we established where and when in the brain specific internal knowledge conceptually interprets the input white noise as a face. We show that internal representations can be reconstructed experimentally from behavioral and brain data, and that their content drives neural activity first over frontal and then over occipitotemporal cortex.

Going back to the source: Why do people trust each other?

Why do we trust people? More precisely, on what basis do we trust people? Reinhard Bachmann's paper, and my response here, are both concerned with this enduring yet curiously neglected question. Ma...

116 CRT optimisation: improving echocardiographic techniques by accommodating biological variability within different echocardiographic parameters

<h3>Background</h3> In optimisation of CRT (and even selection for implantation) we may have underestimated the impact of beat-to-beat variation on echocardiographic measurements. This can be quantified most clearly in the optimisation process, in which genuine small changes in cardiac function (signal) must be detected among potentially large beat-to-beat variation (noise). <h3>Methods and Results</h3> In this large study of biological variability, we performed over 2000 echocardigraphic measurements in 12 patients. We performed separate, replicate measurements at a series of interventricular delays of each potential optimisation modality at rest. This included (i) 3D systolic dyssynchrony index, (ii) aortic pre-ejection time, (iii) interventricular mechanical delay, (iv) LVOT VTI and (v) QRS width. The equivalent of 31 optimisations per patient were performed. For single measurements at each setting, agreement between successive optimisations was low, at 39% for SDI, 41% for aortic pre-ejection time, 32% for IVMD, 54% for LVOT VTI and 58% for QRS width. Agreement between one method and another, using single replicates, was similarly low, with the average agreement between optima by two methods being only 18% similar to pure guesswork. The intraclass correlation coefficient was low for all methods at 0.11, 0.51, 0.30, 0.50 and 0.55 respectively. The intraclass correlation coefficients improved to 0.19, 0.63, 0.42, 0.54 and 0.66 (p=0.001) when averages of paired measurements were used. To optimise within 20 ms or 10 ms of the true optimum, requires a greater number of measurements, as seen in Abstract 116 figure 1, dependant on the intraclass correlation coefficient. The scatter of optima obtained reduced (improved) significantly when using averaged pairs of measurements compared to single measurements from 23 ms to 18 ms (3D SDI), 14 ms to 10 ms (aortic pre-ejection time), 28 ms to 22 ms (IVMD), 21 ms to 16 ms (LVOT VTI) and 14 ms to 10 ms QRS duration (p=0.0002). <h3>Conclusions</h3> Because of beat-to-beat variability, VV delay optimisation by any of the echocardiographic techniques is not realistic unless multiple replicates are performed and averaged. Smoothing biological variation by averaging multiple measurements allows the full potential of echocardiographic optimisation to be achieved and improves the consistency of optimisation. Trying to save time by performing inadequate numbers of replicates is a false economy and leads to optimisation being a form of randomisation. These observations may also cast light on to why attempts to identify future responders from CRT has not – when tested in externally monitored randomised trials—been fruitful: dyssynchrony assessment to select patients for implantation may need averaging too, and of far more replicate measurements than is current practice. Integration of this biological insight into technological achievements of clinical imaging is necessary, if reliable predictors of which patients will benefit from CRT, are to be developed.

Home Testing To Detect Human Immunodeficiency Virus: Boon or Bane?

With the waiver of the Orasure Oraquick rapid human immunodeficiency virus (HIV) test in January 2003, testing for HIV infection in the United States moved from the laboratory to the clinic, the emergency room, and other outpatient settings. By now, millions of rapid HIV tests have been performed, largely by nonlaboratorians and largely outside of dedicated laboratory space. This experience has significantly transformed HIV testing nationally. The next logical step in broadening the settings in which HIV testing can be performed, approval of an HIV test for sale “over the counter” (OTC), involves clinical, technical, psychological, and public health issues along with a fair sprinkling of politics. Much of the rationale for both rapid, “waived” and home-use HIV testing can be summarized by two simple statistics: (i) approximately 30% of HIV-infected persons in the United States are unaware of their serostatus, and (ii) in 2004, 39% of persons with AIDS (e.g., opportunistic infection or CD4+-T-cell count of <200) first tested positive for HIV within 1 year of their AIDS diagnosis (7). Current evaluative approaches are missing substantial numbers of infected persons and detect HIV infection at a later stage than is optimal. Expanding access to HIV testing is a logical approach to addressing these inadequacies. Newly proposed methods for HIV testing must be compared not with an ideal system but with the current state of HIV surveillance and testing. In the United States, kits for home diagnostic testing are available for a limited set of analytes (9). There are currently no OTC tests for infectious diseases; tests for group A streptococcal pharyngitis and for influenza were rejected for home use due to insufficient sensitivity. There are, however, home collection kits for hetatitis C virus and HIV infection that allow consumers to collect specimens and send them to laboratories for testing and direct reporting. The scientific literature on home testing has recently been reviewed and can best be described as “sparse” (12). There have been few studies of the accuracy of home testing methods beyond those performed for Food and Drug Administration (FDA) approval. Even for well-established practices such as home glucose monitoring, there are limited data with respect to outcomes: the recommendations of the American Diabetes Association and the World Health Organization are based primarily on cohort studies and expert opinion and not on controlled studies showing a clinically significant impact on outcomes. The randomized clinical trials that have been performed demonstrated mixed results; a few showed improvement in outcome measures such as hemoglobin A1c levels, but more trials showed no significant effects. Although tests are widely available, an estimation of the clinical or public health impact of any home testing method is nearly pure guesswork at this time.

Working With the Failing Health Care Proxy

Working With the Failing Health Care Proxy

Assessing Early Warning Systems: How Have They Worked in Practice?

Since 1999, the IMF's staff has been tracking several early-warning-system (EWS) models of currency crisis. The results have been mixed. One of the long-horizon models has performed well relative to pure guesswork and to available non-model-based forecasts, such as agency ratings and private analysts' currency crisis risk scores. The data do not speak clearly on the other long-horizon EWS model. The two short-horizon private sector models generally performed poorly.

Assessing Early Warning Systems: How Have They Worked in Practice?

Since 1999, the IMF's staff has been tracking several early-warning-system (EWS) models of currency crisis. The results have been mixed. One of the long-horizon models has performed well relative to pure guesswork and to available non-model-based forecasts, such as agency ratings and private analysts' currency crisis risk scores. The data do not speak clearly on the other long-horizon EWS model. The two short-horizon private sector models generally performed poorly.

Assessing Early Warning Systems: How Have they Worked in Practice?

Since 1999, the IMF's staff has been tracking several early-warning-system (EWS) models of currency crisis. The results have been mixed. One of the long-horizon models has performed well relative to pure guesswork and to available non-model-based forecasts, such as agency ratings and private analysts' currency crisis risk scores. The data do not speak clearly on the other long-horizon EWS model. The two short-horizon private sector models generally performed poorly.

Forlev Nymølle – En offerplads fra yngre førromersk jernalder

Forlev Nymølle – En offerplads fra yngre førromersk jernalder

Comments on cham population figures

All Cambodian population statistics, of whatever period, include a large measure of hypothesis, assumption, extrapolation, and pure guesswork, and they may not be adequate for the type of calculations undertaken by either Kiernan or myself.Ben Kiernan's “Orphans of Genocide: The Cham Muslims of Kampuchea under Pol Pot” (BCAS vol. 20, no. 4, Oct.–Dec. 1988) is an interesting study of the experience of the Chams during 1975–79, and as such makes a valuable contribution to the still too little known social history of Democratic Kampuchea (DK). Unfortunately Kiernan has tinkered with the statistics in a tendentious manner in an attempt to prove the case for genocide in Democratic Kampuchea.

Solar economics—short term costing

Life-cycle cost analysis is traditionally used by advocates of solar energy systems to demonstrate how future increasing annual fuel savings offset the large initial capital expenditure. Payback period and return on investment are cited as proof of the economic desirability of investing in solar. This paper refutes the solar economics based on life-cycle costs as both imaginary and irrelevant. Predicting rates of inflation and fuel escalation, expected life, maintenance costs, and legislation over the next ten to twenty years is pure guesswork. Furthermore, given the high mobility level of the U.S. population, the average consumer is skeptical of long run arguments which will pay returns only to the next owners. In the short-term cost analysis, the house is sold prior to the end of the expected life of the system. The cash flow of the seller and buyer are considered. All the relevant factors, including the federal tex credit and the added value of the house because of the solar system are included.

Price Competitiveness in Export Trade Among Industrial Countries

More than three years have passed since the revaluation of the German mark initiated a period of greater flexibility in exchange rates, and about one year since a new rate structure was agreed at the Smithsonian conference. Academic researchs and governement officials everywhere are scrutinizing current trade data for sign indicating the effectiveness of the realignment, particularly and solid start toward recersals in the deficit of the United States or the surpluses of Japan, Germany, and Canada. The magnitude of the prospective total effect had been assessed largely on the assumption, unconfirmed by empirical work, that the response of trade flows to changes in teh exchange rate would resemble that to changes in foreign trade prices in general; and the timing of the effect was almost pure guesswork.

A markov model of diagnostic errors in assessment of caries experience

Two models of diagnostic errors in caries experience assessment are examined in terms of their theoretical relationship and their maximum difference in caries increment. Assume that μ is the proportion of surfaces over which all diagnoses are certain to be correct, then (1) the independent model assumes all diagnoses over the proportion 1 − μ is pure guesswork regardless what the true condition of the surfaces may be and (2) the dependent model assumes that over 1 − μ, the diagnoses are more likely to be carious than non-carious if the surface condition is truly carious and vice versa. The study shows that the dependent model approaches the independent as a limit, i.e., the independent model is the eigen solution to the dependent model. The maximum difference in the estimate of caries increment is negligible if μ is large.

Assumption of the equal probability of chance success

The “multiple-choice” form of test, in which answer alternatives are given, has frequently met with the objection that an examinee who does not know the correct answer to the item can make a substantial score by chance success. Several methods have been proposed to correct the effect of chance success on items and test statistics. These methods are all based on certain assumptions concerning chance success, which were as follows:(1) An examinee who is ignorant of the correct answer to the item will fail in the free answer form of test, and he will choose the answer at random from the alternatives in the multiple-choice form.(2) All alternatives in an item have the equal probability of chance success, that is, the probability is the reciprocal of the number of alternatives.This study aims at investigating the validity of the above assumptions.Methods: Two parallel mathematical tests consisting of 12 items were prepared, one of which was the “control test” (free answer form), and the other was the “experimental test” of five different forms the 2-alternative form (Form A), the 3-alternative form (Form B), the 4-alternative form (Form C), the 5-alternative form (Form D), and the free answer form (Form E), These tests were given to 3rd grade pupils (N=2, 100) of some secondary schools during October and November, 1964. Ss were divided into two groups:Group 1: A control test was given in the usual way, but the experimental test was given without showing the problems and the examinees were asked to make a pure guesswork on the answer sheets.Group 2: A control and experimental tests were given in the usual way.Results: In the pure guesswork of Group 1, the percentage of response was different among alternatives and the mean score was significantly different from the chance score, contrary to the assumption of the equal probability of choice (Tables 1 and 6-7).The results of Group 2, on the other hand, did not contradict the assumption of chance success. Score obtained were compared with the estimated scores which consisted of the true score and the chance score, and good agreement was obtained. All this is probably due to the fact that the proportion of the chance score in the observed score was so small as to make the difference between the observed score and the estimated score negligible.

Student Thinking on Short Answer Examinations

Anyone who has worked with short-answer examinations must certainly have questioned at times the manner by which students arrive at their choice of responses. Is it pure guesswork? Would they respond in the same manner \i the question were worded differently? Can the student who has intelligence and judgment get by without knowing the facts? It was questions such as these which prompted the inclusion of the items given below in one of the recent comprehensive examinations for Literature and Fine Arts at Michigan State College. In these items the student is required to concern himself with two things only: the recognition of truth or falsity in the statements pre sented, and the determination of the relevancy of those statements to the problem presented. To make adequate responses to the series of items he would need to knowr certain generalizations about the work of Giotto, the chronological relationships existing between Giotto, the Middle Ages, and such painters as Masaccio and Tintoretto, and the meaning of such terms as predecessor, decoration, design, naturalism, mass, space, symbolism, linear perspective, realism, and relevant. The items as they appeared in the examination were stated as follows:

Fish Production in Lakes as a Guide for Estimating Production in Proposed Reservoirs

A LARGE number of artificial reservoirs are being proposed for early construction throughout the United States, which in many cases will have a profound effect on fish and wildlife. It has become imperative, therefore, to attempt to evaluate this effect prior to the completion of construction plans, in order to obtain such modifications in design or water utilization as will assure the maximum benefits to fish and wildlife compatible with other uses and values. This paper touches on only one phase of this evaluation-the quantities of fish that the proposed reservoirs may be expected to produce. Opinions on this subject vary from extreme pessimism to rosy optimism, depending largely on the observers' experience. Admittedly, there is a tremendous difference in the potential yield of various bodies of water, from the 200pounds (or better) per-acre yield of the fertilized, properly-stocked farm pond to the one-pound-per-acre yield of Lake Superior. Yet it is possible to create a useful yardstick by studying observed production data. Such a measure of yield, based on actual experience, is bound to give a more reliable estimate than pure guesswork. There are two types of data available on the populations of fish in lakes and ponds: total populations and annual yields. Unfortunately, both types of data are rarely available for the same body of water. Total population data are available only for small lakes and ponds, chiefly ones in which the fish have been poisoned. Generally speaking, only those ponds have been poisoned whose populations were abnormal in some respect. Either the natural balance between the larger predators and the smaller fish had been upset in such a manner that the lake was crowded with stunted panfish, or the lake had become heavily populated with carp, buffalo, or other rough fish, to the detriment of more desirable species. Obviously, the data from these atypical lakes are not truly representative of the average lake; but being the only data available they are presented for what they are worth. Statistics on the arinual yield of lakes are better than those on total populations because they usually refer to lakes with more or less normal populations. All the available literature on lake production has been examined, and the pertinent data compiled as shown in Table I. However, it was necessary to omit, for various reasons, certain ponds and lakes from consideration. For instance, the annual yield for Standard Lake (16.0 acres) given by Beckman (1941) referred to fish stocked immediately after the poisoning of the entire population, and thus does not represent the yield from a normally balanced population. Cahn (1939) gives the weight of carp taken from Neosha Mill Pond in southern Wisconsin, but not the area of the pond. A preliminary creel census of the trout catch in Fish Lake, Utah, given by Hazzard (1935) is omitted since the study covered but 13 days. Total yields from certain

Patrios Nomos: State Burial in Athens and the Public Cemetery in the Kerameikos

In theClassical Quarterly, 1944, I have dealt with the slender evidence for the Genesia, a public festival of the dead in Athens which was mentioned already in Solon's Axones. Whether or not my suggestion is right that it was introduced by Solon himself as a part of his programme of uniting the classes into the new citizen state by abolishing the festivals of the single clans, or whether the public festival reached farther back, the heortological fact is not in dispute: there existed in Athens, and as far as we know only in Athens, a public festival of the dead, called Genesia, and celebrated in late autumn on the fifth of the month Boedromion with a sacrifice for Mother Earth. That is all we know about it, and in going beyond these clear facts we have to be aware that we pass the border-line into the realm not (I hope) of fiction but of hypothesis, and partly even of pure guesswork. It will depend on the inherent probability of these guesses whether it is worth while to risk them. In my opinion it is worth while, because in the course of our investigation we shall get one unexpected result: namely, the time at which the specifically Athenian custom of burying at home the men killed in action was introduced. And this date, which I believe can be established, will throw some light on the perhaps most famous section of the work of Thucydides, and incidentally on his historical principles.

Through Basque to Minoan: Transliterations and Translations of the Minoan Tablets

IN this book the experiment is tried of assigning modern Basque values to the Minoan characters on bronze age tablets from Crete. As Mr. Gordon says (p. 1), “such a method must obviously begin as pure guess-work”. It also ends there; for “not only did the system yield a language indistinguishable (at present) from Basque, but it revealed unmistakable references to Hellenic deities, several old Greek names, and three poems, one in hexameter verse, one in elegiac, and one in couplets …” etc. Basque is lovely for the purpose: “the language is highly fluid, the aspirate is uncertain, and inversions are common” (p. 2); and “it appears to make no distinction between B, P, and M, T and N, G and K, L and R, O and U”. It was also “an obvious convenience” that “the authors of the script were able to select signs with several meanings” (p. 3); and Mr. Gordon's “method”, as he frankly says (p. 4), “consists in applying a series of hypothetical values, and endeavouring to show that they fit everywhere”. For example (p. 9), with a sign which “appears to represent a conical eminence of some kind, and is provisionally rendered iaq or iq, Basque ik, ‘height’”, he thinks it “possible to write the plural., the agential suffix, the partitive suffix, the past participle, and the imperative singular, besides iising the sign as a connecting link”. English itself has never attempted as much; and it is not. surprising that “it would constantly occur, therefore, as in fact it does”. Another sign (for “a beard, bizal, Basque bizar”) “may also stand for a univalve of contorted type” (for which no Basque word is given), because it “stands as a decoration in a marine subject”, being in fact what the Germans call a “Fullenornament” of the commonest, in Late Minoan pot-painting. Through Basque to Minoan: Transliterations and Translations of the Minoan Tablets. By F. G. Gordon. Pp. v + 83. (London: Oxford University Press, 1931.) 10s. 6d. net.