Initial Presumption Research Articles

Interplay of pulse bandwidth and spectral resolution in spectral-focusing CARS microscopy

We present a theoretical analysis of the relationship among the spectral resolution, the degree of chirp-matching, and pulse bandwidth in coherent anti-Stokes Raman scattering microscopy implementations based on spectral focusing (SF-CARS). We find that, despite allowing better ultimate spectral resolution when chirp-matching is attained, the use of the broadest bandwidth pulses can significantly worsen the spectral resolution if the pulses are not chirp-matched. We demonstrate that the bandwidth of the detected anti-Stokes signal is minimized when the pump is twice as chirped as the Stokes, meaning that—contrary to our initial presumption—a narrow anti-Stokes bandwidth does not imply good spectral resolution. We present approximate expressions that relate the bandwidths of the pump, Stokes, and anti-Stokes pulses to the degree of chirp-matching and outline how these could be used to estimate the amount of glass needed to attain chirp-matching. These expressions also permit a useful estimate of the group delay dispersion from other optics in the pump or Stokes beam path. This work aims to clarify several technical aspects of SF-CARS microscopy and provides researchers with valuable information to consider when working with SF-CARS microscopy systems.

Investigation of Drowning Deaths: A Practical Review.

Drowning, which typically involves a watery environment, remains a serious public health concern claiming an estimated 362 000 lives per year worldwide across all socioeconomic classifications and has remained under close observation by the World Health Organization and its signatories. A significant number of water-related deaths are attributed to accidental drowning, while a smaller but still significant number represent suicidal or homicidal drowning. Others involve a combination of drowning precipitated by injury, intoxication, or environmental extremes. Still others involve victims that die from injury, intoxication, or a natural disease entity of such significance as to preclude the drowning process, while near or in water. While there may be an initial presumption that all water-related deaths are accidental drownings, other possibilities must be considered in the investigation of these types of deaths, as drowning as a cause of death is a diagnosis based on the exclusion of other potential causes. The coordinated investigative efforts of multiple agencies and disciplines are required not only for the designation as drowning as the cause of death but also for death certification. The ongoing analysis and dissemination of data generated from all levels of investigation augment our understanding of the impact on public health and safety, guiding allocation of monetary and educational resources in an effort to prevent further mortality and disability.

Uticaj cene dizel goriva na ekonomske efekte poslovanja ratarskih porodičnih gazdinstava

Bearing in mind the increasing price of diesel fuel, it is necessary to determine its effect on the production of family farms as main factors of agricultural production in Serbia. First of all, it is necessary to pay attention to the farms specializing in crop production because the price of diesel fuel has the biggest influence on economic effects of their production. In order to achieve this goal, the model of a family crop farm was used in this paper. This model was used to determine how the change of diesel fuel market price influences the change of efficiency ratio of the total farm production. Calculations were made for production with subsidies and without them, as well as for two initial presumptions - when the sowing structure of farm was not optimized and when it was. Besides forming models and optimization of production structure, method of sensitive analysis was also used in the paper, starting with a premise that market price of fuel fluctuates in the interval reflecting changes that occur in practice. It was determined by analysis that without optimization of the sowing structure, family farm businesses were economically efficient only with government subsidies. On the other hand, on condition that optimal sowing structure was used, production is economically efficient even without subsidies, except for the case with maximized presupposed fuel price. Ratio of economical efficiency in corn production (as the most important crop in the sowing structure of a family farm) for different yields and corn price with presupposed increase of fuel price was also analyzed in the paper.

Editorial Volume 16 Issue 2

The ability to predict the future would be a useful skill for anyone working in the acute medical unit. While crystal balls have not yet become standard issue for acute medicine trainees, a variety of tools now exist to help identify the likely outcome for patients referred for hospital admission – and enable their management to be planned. Two articles in this summer edition of Acute Medicine highlight this important issue. The team from Athens led by Sotirios Kakavas have investigated the prognostic value of beta-2 microglobulin in patients admitted to hospital with pulmonary embolism. Higher levels of this inflammatory protein were associated with a worse outcome, suggesting that it may have a role in identifying those patients who would benefit from management in a higher dependency setting. All patients in their cohort were admitted to hospital, which is clearly different to the established practice in many UK acute medical units where significant proportions of patients are now managed via ambulatory care. Identification of the low-risk patient who can safely be managed without in-patient monitoring will still require a different approach. However, the results of this study suggest that there may be a role for beta-2 microglobulin, either alone or in combination with other markers, in future prognostic modelling. The ALICE score, developed by the acute medicine team in Plymouth, appears to perform well in a variety of hospitals in predicting length of stay for patients admitted to hospital. The paper by Dan Wilding and Kate Evans indicates that a lower score predicts a shorter hospital stay, which could have significant implications. It is well established that unnecessary in-patient transfers can result in delays in care which may extend a patient’s time in hospital. Accurate, early identification of those patients who are most likely to be able to go home within 48-72hours may help to reduce transfers and improve the efficiency of the service. Of course, this will still be dependent on there being sufficient capacity to enable patients to remain on the acute medical unit for this time pending discharge, as well as good communication with bed management teams. The overnight transfer of patients whose discharge from hospital the next day was predicted and planned is a common source of frustration, when hospital capacity is under duress – as now seems to the case in most hospitals throughout the year. This edition includes just a single case report, although we have several lined up for future editions later in the year. Although liver abscess is not an uncommon problem, the case highlights the important issue of ‘source control’ in the management of sepsis. The patient described was clearly unwell at the time of admission, and deteriorated further, despite rapid initiation of antibiotics and other ‘sepsis 6’ measures. The clinical and radiological evidence of pneumonia was compelling, but recognition, and early drainage of the abscess resulted in a rapid improvement, as well as confirmation of the causative organism. Clues to the cause included a past history of complicated diverticular disease and mild derangement of liver function, but relatively little in the way of abdominal findings such that this would have been an easy diagnosis to miss, if the acute medicine team had not been alert to this possibility. We must never be afraid to challenge out initial presumptions, particularly when a patient’s condition fails to improve. I am delighted that Mark Holland has provided a ‘Viewpoint’ article for this edition, reflecting on his tenure as President of the Society for Acute Medicine. Mark hands over to Nick Scriven in the Autumn – no doubt, he will be feeling a sense of relief tinged with a little sadness, which I remember well when my time in the role came to an end in 2013. Mark has been a great asset to the Society and should be very proud of his achievements in raising the profile of the Speciality of Acute Medicine. I hope you enjoy whatever remains of summer, and that you can all manage some respite before the start of the ‘predictable’ pressures of the months which follow.

Rapid triage of victims suspected of a chemical attack: A one-page sheet allowing identifying the toxidrome. The doctors without borders (MSF) experience

Over the past five years, events in the Middle East have increased the awareness about the possible use of chemical weapons and their surrogates, the so-called “toxic industrialized compounds”. The major issue is to identify on a clinical basis the likelihood of exposure to chemicals ranging from riots agents to lethal agents in order – to advice protection of rescuers and care givers at the scene – to provide adapted treatment to casualties, and; – to address the need for antidote supply. Systematic review of the literature on acute chemical accidents resulting in casualties to identify easily collected clinical signs and symptoms resulting. This review provided a limited list of signs to be collected in a small subset of frankly symptomatic patients. The signs and symptoms were classified according to the corresponding organ(s) involved by chemical injury. All signs shoud be clinically collected using current physical examination. There are presently three versions of the sheet: French, English, and Arabic. Owing to the political context and analytical difficulties, we never attempted at determining the agent having caused signs and symptoms. The one-page questionnaire was used in 5 settings, including – a chemical incident related to the opening of a chemical plan in Lumumbashi in 2011; – the repeated use of anticholinesterasic agents towards civilians in Syria from April 2013 up to that the attack launched the 21st of August 2013; – repeated chlorine attack towards civilians in Syria since March 2014; – an attack using a vesicant agent towards civilians in August 2015 in Syria, and; – the acute onset of paraplegia in Mali on Summer 2015. In each setting, the analysis of the quoted items on the sheet allowed to suggest the class of the toxicant within a few hours after exposure. In the case of exposure to chlorine and to the vesicant agent, two collections of signs over a period of a few hours were needed to draw definitive conclusion. The lowest number of casualties in an exposure was three after exposure to vesicant agents. The definitive diagnosis was in accord with the initial presumption regarding the class of toxicant. Early identification allowed to advise adapted protection of caregivers at the site as well as define the need for antidote supply and the nature of the antidote. Conversely, in one setting (Mali 2015) a toxic origin was ruled out as not fitting any known toxicant while an infectious disease was identified as the likely cause of the outbreak. In case of incident, a one-page sheet of the list of signs and symptoms allowed to define a toxidrome specific of a class of toxicant, helped in protecting rescuers and care givers and refined the needs for supportive and antidotal treatment. Repeated collection of signs may be required in agents acting over hours. A close collaboration with a skilled toxicologist is needed when facing incident involving hazardous materials. At the scene only chemical incident was identified. However, repetition of bombing in the same area resulted in a more accurate and rapid medical response. A one-page sheet easily filled out at the scene in the context of chemical incident allowed defining the toxidrome and consequently protection of rescuers, needs for supportive and antidotal supply. Owing to the rapidity of action of a number of toxicant a single or repeated examination over a few hours is needed to define the toxidrome and therefore the class of toxicant.

BKL Method in the Bianchi IX Universe Model Revisited

Given the extreme difficulty in finding analytical solutions to Einstein’s equations for universe models, such as the Bianchi type IX, different physical-mathematical techniques have been designed to attempt to find, at least approximate solutions that could have relevance in modern cosmology. Belinskii, Khalatnikov and Lifshitz (BKL) have developed a method to study a particular time evolution dynamic of the Bianchi type IX universe model. Herein, it is shown that this method contains pitfalls. These pitfalls, among other things, prevent the conclusion that this model provides chaotic behaviour. We show that the initial presumption made by BKL turns out to be inconsistent with the assumed initial conditions, since it cannot be kept along with the time-extended BKL process. That is, the Kasner stipulations corresponding to ???, taken as initial conditions, are at odds with the initial assumption imposed on Einstein’s field equations.

Intoxicación familiar por mercurio elemental: Caso clínico

Family poisoned by elemental mercury: a case report Introduction: Mercury is a heavy metal widely dispersed in nature, occurring in three chemical forms. Ex- posure to mercury at work sites and even at home may be clinically significant. Objective: To update the knowledge about the risks of this toxic element. Case report: the case of a teenager and his family poisoned by elemental mercury is reported. The diagnostic process was difficult, mainly due to an initial presumption of probable infectious etiology, unavailability of key anamnestic data and unusual clinical behavior, with signs and symptoms of multisystem compromise (neurological, hepatic, renal and dermatological compromise). Discussion: The study was based on literature review of various clinical presentations regarding this poisoning and its management, emphasizing the need for dimercaptosuccinic acid chelator. As a major public health pro- blem, the importance of education and implementation of public policies to have a mercury-free environment is discussed.

Intraoral Schwannomas: presentation of a series of 12 cases

Introduction: Schwannomas are benign and not very frequent tumors of the peripheral nerves, derived from the nerve supporting Schwann cells. Study Design: Data were collected on the clinical manifestations (sex, age), location, size and symptonts of the lesions as well as the evolution time and the initial (presumption) diagnosis. Results: Twelve patients were documented, with a mean age of 29,5 ± 12,1 years (range 16-50) and a balanced gender distribution. The mean duration of the lesions was 42,17± 45,3 months. The lesion located in the floor of the mouth was the largest tumor, measuring about 4 cm in maximum diameter, while the average size of the 12 schwannomas was 2.04± 1.1 cm. Conclusion: We present 12 oral schwannomas diagnosed and treated over a period of 10 years. Key words:Schwannomas, oral benign tumor, neurilemmoma.

The Temptations of Theory

When students of religion are tempted to theorize, they are more apt to spread confusion than to get things right. In Believing and Acting (2012), Scott Davis offers philosophical therapy for the resulting perplexities. There is no more instructive methodological essay in the field. Because the temptations Davis identifies are real, any would-be theorist of religion, society, or culture would be well advised to take his diagnoses seriously. “Understanding religion,” according to Davis, “requires nothing more than the sensitive and imaginative reading of human phenomena informed by the best available historical narrative.” The study of religion is a tangled garden in need of “judicious pruning and weeding” (2012, 3). In some cases, the prudent gardener will need only to reshape something that goes by the name of “theory.” Davis praises Mary Douglas, Clifford Geertz, and Wayne Proudfoot for freeing earlier research programs of their theoretical excesses. These are Davis’s model gardeners, the heroes of “the pragmatic turn” he recommends. What links the three together, he argues, is that they borrow their pruning hooks from the same shed—the pragmatic philosophical tradition initiated by C. S. Peirce.1 The book has villains as well as heroes. In “cognitive studies and the postmodern hermeneutics of suspicion,” Davis finds nothing worth saving. He concludes that they “should probably be uprooted altogether” (2012, 4). In somewhat different ways, these programs fail to learn what pragmatism has to teach about studying human beings as rational agents. The lessons that figure most heavily in Davis’s critical project come from Donald Davidson.2 While I mostly agree with Davis on what those lessons are and admire the acumen with which he explicates them, I worry that he is too quick to dismiss some research programs as worthless. If we are not careful here, something valuable will end up in the compost heap. Davis argues that Peirce was basically right about how inquiry works. Inquiry is the activity in which human beings engage to resolve their doubts about what is the case and what to do. Like other things we do, it is something we can do well or poorly. Properly conducted, inquiry is part of living well.

Learning From Within to Ensure a Successful Implementation of an Electronic Health Record

Implementation of an electronic health record has multiple facility-wide challenges affecting all direct care providers. Because the dialysis unit and emergency department had already undergone transition with differing electronic systems several years before, could anything be learned from these past experiences to inform the future institution-wide implementation? Utilizing focus groups and surveys, recurring themes emerged: "It will take one hundred charts"; allowing for "self-discovery" of individual learning progression; establishing and communicating "clear processes" for use of the electronic record; and ensuring adequate support to facilitate a "customer-focused" approach in learning how to utilize electronic documentation. Although training related to the electronic health record was discussed in all focus groups, training was not described as a main concern, which challenged our initial presumptions that education was the key resource for a successful change. Three of the four themes uncovered in this study are not unique and corroborate the findings in other studies. "Clear processes" is a new theme not previously identified. These themes with recommendations were presented to the electronic health record design team to assist with the hospital-wide implementation.

Optimization of the mean radius flow path of a multi-stage steam turbine with evolution algorithms

A prototype model of the mean radius flow path of a four-stage, high speed 1 MWe axial steam turbine was optimized by using evolution algorithms, DE (differential evolution) algorithm in this case. Also the cost-benefits of the optimization were inspected. The optimization was successfully performed but the accuracy of the optimization was slightly less than hoped when compared to the control modeling executed with the CFD (computational fluid dynamics). The mentioned inaccuracy could have been hardly avoided because of problems with an initial presumption involving semi-empiric calculations and of the uncertainty concerning the absolute areas of qualification of the functions. This kind of algebraic modeling was essential for the success of the optimization because e.g. CFD-calculation could not have been done on each step of the optimization. During the optimization some problems occurred with the adequacy of the computer capacity and with finding a suitable solution that would keep the algorithms within mathematically allowable boundaries but would not restrict the progress of the optimization too much. The rest of the problems were due to the novelty of the application and problems with preciseness when handling the areas of qualification of the functions. Although the accuracy of the optimization results was not exactly in accordance with the objective, they did have a favorable effect on the designing of the turbine. The optimization executed with the help of the DE-algorithm got at least about 3.5 % more power out of the turbine which means about 150 000 € cost-benefit per turbine in the form of additional electricity capacity.

PECULIARITIES OF FDI PERFORMANCE IN DEVELOPED, DEVELOPING AND UNDERDEVELOPED COUNTRIES

The aim of this article is to evaluate impact of FDI on sustainable development indicators of differently developed countries during two periods of time: a time span before (2000−2007) and a time span embracing the global economic crisis period (2000–2009). Reviewed ample supply of relevant scientific literature made a presumption to arise that the impact of FDI differs in developed, developing and underdeveloped countries, i.e. depends on the level of development: developed countries benefit most, developing less and underdeveloped least. Countries are attributed to respective groups according to their level of development and indicators are chosen for investigation. The following indicators capable of reflecting FDI impact on enhancing wellbeing in unevenly developed countries are: GDP, exports, inflation, population, life expectancy at birth, primary school pupils, infant mortality, total health expenditure per capita, total tax rate, internet users, residential consumption of electricity , and differences between developed and underdeveloped countries in the field of economic, social, business environment are taken into account. Several other hypotheses have been formulated and FDI impact on sustainable development indicators has been estimated with the help of empirical research in order to test the initial presumption. Obtained results enabled to compare peculiarities of FDI performance during two periods of time.

Music therapy as a caring intervention: Swedish musicians learning a new professional field

The question of competence in providing music therapy has rarely been the focus of interest in empirical research, as most music therapy research aims at measuring outcomes. Therefore, the aim of this study is to analyse and describe musicians’ learning processes when they study music therapy as a caring intervention. An initial presumption is that musicians are highly qualified to take advantage of the potential of music but need to become familiar with the caring perspective. Ten freelance musicians participated in an education programme with music therapy anchored in a lifeworld-oriented caring science model. They were interviewed about their learning experiences. The data was analysed according to a phenomenographic method. The musicians’ understanding of their learning music therapy is described in terms of four qualitative categories: conversion, openness, reflection and practice. Learning as a continuous process is discussed in relation to pedagogic theories about tacit knowledge and ‘learning by doing’.

Photosynthetic induction in broadleaved Fagus sylvatica and coniferous Picea abies cultivated under ambient and elevated CO 2 concentrations

The hypothesis that elevated CO 2 leads to a faster induction of photosynthesis was tested using 7–8-year-old seedlings of broadleaved Fagus sylvatica and coniferous Picea abies exposed for three growing seasons to ambient (385 μmol mol −1; AC) and elevated CO 2 (700 μmol mol −1; EC). Since the photosynthetic induction is primarily determined by light modulations of Rubisco activity and stomata opening, the hypothesis was based on the following presumptions: (1) EC reduces the content of Rubisco in leaves, (2) decreases stomatal conductance, and (3) has no effect on the rates of stomatal opening and Rubisco activation upon illumination. Thus, reduced maxima of Rubisco activity and stomatal conductance should be reached faster in EC compared to AC plants after leaf transition from dark to light. The initial presumptions were confirmed, since reductions of Rubisco content (up to 28% and 48%) and light-saturated stomatal conductance ( G Smax; up to 40% and 50%) were observed in EC treated F. sylvatica and P. abies as compared to AC ones. However, the presumption of constant induction rates was not confirmed. A slight decrease of the time constant for Rubisco activation (14–27%) was observed as the result of EC treatment in both tree species, whereas stomatal opening rates significantly decreased in F. sylvatica (up to 48%) and remained almost unchanged in P. abies. Thus, EC treatment led to the stimulation of the initial phase of photosynthetic induction. This was demonstrated by higher values of the induction state 60 s after leaf illumination (IS 60), determined in both F. sylvatica (up to 129%) and P. abies (up to 108%) as compared to AC treatment. In contrast, the stimulation of the secondary phase of photosynthetic induction, reflecting mainly stomatal opening and described by the time required to reach 90% of maximum steady-state photosynthesis ( T 90( A)), was only 5–15% in F. sylvatica (non-significant) and 21–28% in P. abies (significant). The reduced rates of stomatal opening by EC treatment thus may limit the general validity of the hypothesis .

Fallacies of Virtualization

The recent rapprochement between Science and Technology Studies (STS) and Political Science (PS) is induced by the broadened understanding of political action. The debate concerning the nature of ``the political'' produces an important question concerning the possibilities of an issue- or object-oriented focus for understanding political action. The purpose of this article is to contribute to this debate through an analysis of how relations between material and social entities are continuously recontextualized and decontextualized in social and political interaction. The authors discuss established approaches to explain the concept of virtualization. Virtualization is then used in a case study on the implementation of manure regulation in East Fryslân, the Netherlands, to illustrate how cases or issues are virtualized in political decision making, which produces initial presumptions that carry conclusive weight. The authors conclude that a broad understanding of the political in both STS and PS can only be sustained through an understanding of how relations between social and material entities are continuously decontextualized and recontextualized in political and social interaction.

Endogenous Indoctrination: Occupational Choice, the Evolution of Beliefs, and the Political Economy of Reform

Much of the political economy analysis of reform focuses on the conflict of interest between groups that stand to gain or lose from the competing policy proposals. In reality, there is also a lot of disagreement about the working of the policy: in addition to conflicting interests, conflicting views play an important role. Those views are shaped in part by an educational bureaucracy. It is documented that the beliefs of that bureaucracy differ substantially from those of the broader constituency. I analyse a model where this effect originates in the self-selection of workers in the educational occupation, and is partly reinforced by the insulation of the educational profession from the real economy (an effect which had been discussed by Hayek). The bias makes it harder for the population to learn the true parameters of the economy if these are favourable to the market economy. Two parameters that govern this capacity to learn are social entropy and heritability. Social entropy defines how predictable one’s occupation is as a function of one’s beliefs. Heritability is the weight of the family’s beliefs in the determination of the priors of a new generation. Both heritability and social entropy reduce the bias and makes it easier to learn that the market economy is good, under the assumption that it is. Finally I argue that the capacity to learn from experience is itself affected by economic institutions. A society which does not trust markets is more likely to favour labour market rigidities that in turn reduces the exposure of individuals to the market economy, and thus their ability to learn from experience. This in turn reinforces the weight of the educational system in the formation of beliefs, thus validating the initial presumption against the market economy. This sustains an equilibrium where beliefs and institutions reinforce each other in slowing or preventing people from learning the correct underlying parameters.

Detection of ileocecal Crohn's disease using ultrasound as the primary imaging modality.

At our hospital ultrasound (US) is used as an initial screening procedure in all patients with abdominal symptoms. The purpose of this study was to assess the effect of this policy on the detection of ileocecal Crohn's disease. We retrospectively studied all patients with a new diagnosis of ileocecal Crohn's disease from our institute over the period 1990-2001. The final diagnosis was based on clinical follow-up and pathological, surgical, US, and other radiological findings. We noted who referred the patient to the radiology department, what the initial clinical presumption was, and what the first imaging study was. US diagnoses were determined from the initial US report and US findings were registered from the images. There were a total of 47 patients (20 men, 27 women) with a mean age of 30 years and a median age of 27 years (range 14-75 years). In all patients the initial imaging study was an abdominal US. Using US, a confident diagnosis of ileocecal Crohn's disease was made in 35 of the 47 patients, Crohn's disease was suggested among the differential diagnosis in 10, and an incorrect diagnosis was made in 2 patients. In 28 of 47 patients, the referring physician did not consider Crohn's disease when requesting the initial US examination. In eight patients with appendicitis-like symptoms, the US findings strongly influenced the decision to refrain from operation at that point in time. US, when used as a low-threshold diagnostic procedure, is a reliable and noninvasive means for making an early diagnosis of ileocecal Crohn's disease in patients who present with atypical symptoms. It may prevent both unnecessary therapeutic delay as well as unnecessary surgery.

Student demographics as a predictor of use of an educational software program

Nearly ten years after the first democratic elections in South Africa, educators are still concerned about the needs of disadvantaged students, particularly when introducing computer technology into the educational process. This article reports on the findings of a research project, which explored the use of a Computer Assisted Education program by students from diverse ethnic, educational and language backgrounds. The results showed that initial presumptions that disadvantaged students would be excluded from the use of the technology may be inaccurate. South African Journal of Education Vol.24(1) 2004: 42-48

Kleine Büromärkte

Since the 1990s, at the latest, property markets in German cities have been analyzed and documented regularly and comprehensively. But this applies only to the top locations. There is hardly anything known about property markets in smaller cities, in particular office markets. A student research project at the Technical University in Hamburg-Harburg has looked into this matter. The initial presumption was that low rents and high yields could hardly allow successful real estate development. But, if project developers do not provide potential tenants with a sufficient volume of office space, demanding companies are forced to invest their own equity in owner-occupied real estate or to take available office space that does not support optimum performance conditions. Both alternatives mean disadvantages for local companies. The research project took place in the mid-size city of Braunschweig, where approximately 200,000 sqm of office space has been constructed since the beginning of the 1990s. Asked about thei...

Is it Meaningful to use Biochemical Parameters to Discriminate Between Transudative and Exudative Pleural Effusions?

The usefulness of biochemical criteria to separate pleural transudates from exudates is controversial, and the limitations of Light's criteria in patients receiving diuretic therapy is of general concern. We evaluated the added value of biochemical criteria to clinical judgment for separating transudates from exudates. A community teaching hospital. A prospective, observational study for the evaluation of diagnostic tests. In 249 consecutive patients referred for diagnostic thoracentesis, two physicians classified the pleural effusion as transudate or exudate based on all available information just before performing the thoracentesis. The sensitivity, specificity, and accuracy of the clinical presumption were compared with those of Light's criteria, and serum-pleural fluid albumin and protein gradients. The combined accuracy of biochemical and clinical criteria was also assessed. The accuracy of Light's criteria (93%) was significantly higher than that showed by the initial clinical presumption (84%; p < 0.01) and that of the alternative biochemical criteria: serum-pleural fluid albumin gradient (87%; p < 0.03) and serum-pleural fluid protein gradient (86%; p < 0.01). In patients receiving diuretic therapy, the accuracy of Light's criteria was 83% (60 of 72 cases), neither different to that of the albumin gradient (88%; 63 of 72 cases) nor to that of the protein gradient (86%; 62 of 72 cases). When these alternative biochemical criteria were applied exclusively to patients receiving diuretics who were thought to have a transudative effusion by clinical criteria, but having fluid identified as exudative by Light's criteria, the results did not improve significantly. Using a multiparametric model for the population receiving diuretics, the accuracy was greater (93%; 67 of 72 cases) than that of Light's criteria but without reaching statistical significance (p = 0.12). Light's criteria are significantly superior to the clinical presumption to separate pleural transudates from exudates. In patients receiving diuretics, Light's criteria lose accuracy, which is similar to that showed by the use of alternative biochemical criteria alone or combined with clinical judgment.