Probit Analysis (probit + analysis)

Distribution by Scientific Domains


Selected Abstracts


Rights Offerings and Corporate Financial Condition

FINANCIAL MANAGEMENT, Issue 1 2006
Nancy D. Ursel
Certain American industrial firms still use equity rights offerings. Most of these offerings are uninsured. I examine firms' financing decisions, and develop the explanation that rights offerings are used by firms in financial distress with difficulty accessing underwriting services. These firms have little to lose from the costs of adverse selection that accompany the lack of underwriter certification of uninsured rights offerings. Probit analysis of 660 seasoned NYSE, Amex, and Nasdaq equity issues between 1983,1999 yields results consistent with my explanation. There is no evidence that variables previously linked to rights usage (e.g., ownership concentration) continue to be relevant to the issue method choice. [source]


Insecticidal activity of 23 essential oils and their major compounds against adult Lipaphis pseudobrassicae (Davis) (Aphididae: Homoptera)

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 11 2005
Blair J Sampson
Abstract Essential oils from 23 species of plants comprising 14 genera and 4 plant families were obtained by Clevenger-type water distillation. The major compounds in these essential oils were identified with GC-MS and their insecticidal activity against adult turnip aphids, Lipaphis pseudobrassicae (Davis), tested with dosage-mortality bioassays. We examined mortality only for viviparous adults because sizeable aphid populations on crucifer (Brassicaceae) hosts are largely produced by these wingless, parthenogenic females. Twenty-two of the oils were directly applied to aphid females in randomized blocks at concentrations of 0.0, 1.0, 2.5, 5.0 and 10.0 mg ml,1. Essential oils mixed with a non-toxic emulsifying agent, dimethyl sulfoxide (DMSO), more easily penetrated the waxy insect cuticle. Probit analysis and LC50 at three different exposures showed aphids were quickly incapacitated and killed by aliphatic aldehydes, phenols and monocyclic terpenes contained in Bifora and Satureja oils and at applied concentrations as low as 0.3 to 1.0 mg ml,1. Only enough Pimpinella isaurica oil and its three phenylpropanoid fractions were available for testing at a single concentration of 10 mg ml,1. We could not spare any additional P. isaurica oil for testing at other concentrations. Phenylpropanoids isolated from P. isaurica oil when recombined or left naturally blended in the oil were highly bioactive against L. pseudobrassicae at 10 mg ml,1. Copyright © 2005 Society of Chemical Industry [source]


Leaf surfaces and the bioavailability of pesticide residues

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 5 2001
M Nasir U Chowdhury
Abstract Laboratory bioassays were carried out to determine the toxicity to Folsomia candida Willem (Collembola: Isotomidae) of residues of a pyrethroid insecticide, deltamethrin, and an organophosphorus insecticide, dimethoate, on different leaf surfaces. The test leaves included a range of species and leaves of different ages. Dose-response relationships were estimated for F candida walking over the various treated leaf substrates. Probit analysis was used to estimate the means and standard deviations of the associated tolerance distributions expressed as g,AI,ha,1. Parallelism tests were undertaken to compare the susceptibilities of F candida to the two compounds applied to the different leaf surfaces. On deltamethrin-treated leaf surfaces, the LD50 values for F candida varied from 6.36 to 77.14,g,AI,ha,1. F candida was least susceptible to deltamethrin residues when applied to leaves of dwarf bean (Phaseolus vulgarus L) and the highest susceptibility was observed following application to leaves of seedlings of barley (Hordeum vulgare L). In contrast, the LD50 values observed for dimethoate treatments did not differ significantly between leaf types, ranging from 1.35 to 8.69,g,AI,ha,1. The laboratory data on susceptibility of F candida on different leaf types for different pesticides can be used to investigate the role of leaf surface properties in modifying the toxicity of applied pesticides to exposed invertebrates. © 2001 Society of Chemical Industry [source]


The optimum concentration of levobupivacaine for intra-operative caudal analgesia in children undergoing inguinal hernia repair at equal volumes of injectate

ANAESTHESIA, Issue 1 2009
Y.-S. Yao
Summary Probit analysis was used to predict the median effective concentration (EC50) and the 95% effective concentration (EC95) values of levobupivacaine for caudal analgesia in children at equal volumes of injectate. Sixty children scheduled for inguinal herniorrhaphy were recruited. Anaesthesia was induced with sevofurane and nitrous oxide. Then caudal block (total volume of local anaesthetic 1 ml.kg,1) was performed. Patients randomly received one of six concentrations (0.08%, 0.10%, 0.12%, 0.14%, 0.16% or 0.18%) of levobupivacaine. Thereafter, inhalational anaesthetics were discontinued and intravenous midazolam 0.1 mg.kg,1 was administered to maintain sedation. The effective caudal analgesia was defined as an absence of gross movements and a haemodynamic (heart rate or blood pressure) reaction < 20% compared with baseline in response to surgical incision. Our data indicated that the EC50 and EC95 values of levobupivacaine for caudal analgesia were 0.109% (95% confidence intervals 0.098,0.120%) and 0.151% (95% confidence intervals 0.135,0.193%) when using the same volume (1 ml.kg,1), respectively. [source]


Interactions between bipolar disorder and antisocial personality disorder in trait impulsivity and severity of illness

ACTA PSYCHIATRICA SCANDINAVICA, Issue 6 2010
A. C. Swann
Swann AC, Lijffijt M, Lane SD, Steinberg JL, Moeller FG. Interactions between bipolar disorder and antisocial personality disorder in trait impulsivity and severity of illness. Objective:, We investigated trait impulsivity in bipolar disorder and antisocial personality disorder (ASPD) with respect to severity and course of illness. Method:, Subjects included 78 controls, 34 ASPD, 61 bipolar disorder without Axis II disorder, and 24 bipolar disorder with ASPD, by Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) (SCID-I and -II). Data were analyzed using general linear model and probit analysis. Results:, Barratt Impulsiveness Scale (BIS-11) scores were higher in ASPD (effect sizes 0.5,0.8) or bipolar disorder (effect size 1.45) than in controls. Subjects with both had more suicide attempts and previous episodes than bipolar disorder alone, and more substance-use disorders and suicide attempts than ASPD alone. BIS-11 scores were not related to severity of crimes. Conclusion:, Impulsivity was higher in bipolar disorder with or without ASPD than in ASPD alone, and higher in ASPD than in controls. Adverse effects of bipolar disorder in ASPD, but not of ASPD in bipolar disorder, were accounted for by increased impulsivity. [source]


Risk assessment of Magnacide® H herbicide at Río Colorado irrigation channels (Argentina). tier 3: Studies on native species

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2007
Andrés Venturino
Abstract We evaluated the potential environmental risk of the herbicide Magnacide® (Baker Petrolite, TX, USA) using native species from Argentina, representing the ecosystem at the Irrigation Corporation (CORFO) channels at the Colorado River mouth, Buenos Aires, Argentina. Six species including fish, toads, snails, crustaceans, and insects were selected to perform studies on acute toxicity and repeated exposure effects. Magnacide H susceptibility ranking was Bufo arenarum (lethal concentration 50 [LC50] = 0.023 mg/L), Onchorhynchus mykiss (LC50 = 0.038 mg/L), Heleobia parchappii (LC50 = 0.21 mg/L), Hyalella curvispina (LC50 = 0.24 mg/L), Simulium spp. (LC50 = 0.60 mg/L), and Chironomus spp. (LC50 = 2.83 mg/L). The risk limit of 10th percentile (0.013 mg/L) determined by probit analysis on sensitivity distribution was similar to the one calculated from literature data. Risk assessment based on field application data suggested lethal exposures for more than 70 to 90% of the species up to 20 km downstream from the application point. Repeated exposures to Magnacide H of amphibian larvae at the lowest-observed-effect concentration caused some effects during the first exposure, but without cumulative effects. Amphipods were insensitive to repeated exposures, showing no cumulative effects. Whether short-term exposures may result in long-term sublethal effects on the organism's life history was not addressed by these laboratory tests. In conclusion, tier 3 studies indicate that Magnacide H application schedule is extremely toxic for most native species at CORFO,Río Colorado channels, representing a high potential risk in the environment. The real environmental impact must be addressed by field studies at tier 4 giving more information on population effects and communities. [source]


Developmental effects of bioaccumulated selenium in eggs and larvae of two salmonid species

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2005
Jodi Holm
Abstract Elevated concentrations of Se have been detected in cold, flowing water habitats near uranium and coal mines in Canada. Fish from these systems have concentrations of Se in their tissues that exceed toxic effect thresholds that have been established for warm-water fishes. However, the applicability of toxic effect thresholds and guidelines to cold water, lotic habitats is a matter of contention in the literature since most cases of Se toxicosis have been documented in standing, warm-water systems. To examine the possibility of impaired reproduction in wild rainbow trout (Oncorhynchus mykiss) and brook trout (Salvelinus fontinalis) near coal mining activity in the northeastern slopes region of Alberta, Canada, spawn from both species were collected from exposure and reference sites. Gametes were fertilized in the laboratory, reared to the swim-up stage, and examined for deformities. A significant relationship was observed for rainbow trout between the amount of Se in eggs and the incidence of developmental abnormalities, specifically craniofacial defects, skeletal deformities, and edema. These associations approximate exponential functions with probabilities that 15% of the population would be affected occurring between 8.8 and 10.5 ,g Se per gram of wet egg weight, based on probit analysis. These relationships are similar to those described for centrarchids inhabiting a seleniferous warm-water lake. No such relationships were established for brook trout. [source]


The individual tolerance concept is not the sole explanation for the probit dose-effect model,

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2000
Michael C. Newman
Abstract Predominant methods for analyzing dose- or concentration-effect data (i.e., probit analysis) are based on the concept of individual tolerance or individual effective dose (IED, the smallest characteristic dose needed to kill an individual). An alternative explanation (stochasticity hypothesis) is that individuals do not have unique tolerances: death results from stochastic processes occurring similarly in all individuals. These opposing hypotheses were tested with two types of experiments. First, time to stupefaction (TTS) was measured for zebra fish (Brachydanio rerio) exposed to benzocaine. The same 40 fish were exposed during five trials to test if the same order for TTS was maintained among trials. The IED hypothesis was supported with a minor stochastic component being present. Second, eastern mosquitofish (Gambusia holbrooki) were exposed to sublethal or lethal NaCl concentrations until a large portion of the lethally exposed fish died. After sufficient time for recovery, fish sublethally exposed and fish surviving lethal exposure were exposed simultaneously to lethal NaCl concentrations. No statistically significant effect was found of previous exposure on survival time but a large stochastic component to the survival dynamics was obvious. Repetition of this second type of test with pentachlorophenol also provided no support for the IED hypothesis. We conclude that neither hypothesis alone was the sole or dominant explanation for the lognormal (probit) model. Determination of the correct explanation (IED or stochastic) or the relative contributions of each is crucial to predicting consequences to populations after repeated or chronic exposures to any particular toxicant. [source]


The optimal bolus dose of alfentanil for tracheal intubation during sevoflurane induction without neuromuscular blockade in day-case anaesthesia

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2008
J. Y. KIM
Background: The purpose of this study was to determine the optimal bolus dose of alfentanil required to provide successful intubating conditions following inhalation induction of anaesthesia using 5% sevoflurane and 60% nitrous oxide without neuromuscular blockade in adult day-case anaesthesia. Methods: Twenty-four adults, aged 18,60 years, undergoing general anaesthesia for short ambulatory surgery were enroled into the study. After vital capacity induction, with sevoflurane 5% and 60% nitrous oxide in oxygen, pre-determined dose of alfentanil was injected over 30 s. The dose of alfentanil was determined by modified Dixon's up-and-down method (2 ,g/kg as a step size). Ninety seconds after the end of bolus administration of alfentanil, the trachea was intubated. Systolic blood pressure, heart rate and SpO2 were recorded at anaesthetic induction, before, 1 min and 3 min after intubation. Results: The bolus dose of alfentanil for successful tracheal intubation was 10.7±2.1 ,g/kg in 50% of patients during inhalation induction. From probit analysis, 50% effective dose (ED50) and ED95 values (95% confidence limits) of alfentanil were 10.7 ,g/kg (8.0,12.9 ,g/kg) and 14.9 ,g/kg (12.9,31.1 ,g/kg), respectively. Conclusions: Using the modified Dixon's up-and-down method, the bolus dose of alfentanil for successful tracheal intubation was 10.7±2.1 ,g/kg in 50% of adult patients during inhalation induction using 5% sevoflurane and 60% nitrous oxide in oxygen without neuromuscular blocking agent in day-case anaesthesia. [source]


Ideas, Economic Pressures, and Pension Privatization

LATIN AMERICAN POLITICS AND SOCIETY, Issue 2 2005
Raúl L. Madrid
ABSTRACT This article maintains that the recent wave of pension privatization has been spurred largely by rising pension expenditures and chronic capital shortages. Many policymakers in Latin America and around the world believed that privatizing their public pension systems would boost their domestic savings rate and resolve the systems' financial problems, thereby reducing their dependence on unstable foreign capital and freeing resources for other, more productive uses. There is no clear evidence that pension privatization will bring these economic benefits, however. To understand why policymakers held these beliefs, we must examine how ideas about pension privatization have formed. Two particularly important factors are the Chilean model and the World Bank's growing influence on pension policy. A probit analysis of the determinants of pension privatization provides support for these arguments. [source]


Fumigation toxicity of volatile natural and synthetic cyanohydrins to stored-product pests and activity as soil fumigants

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 8 2004
Dong-Sik Park
Abstract Insecticidal fumigation toxicity of natural and synthetic cyanohydrins was evaluated with four stored-product pests: the lesser grain borer, Rhyzopertha dominica (F), the red flour beetle, Tribolium castaneum Herbst, the saw-toothed grain beetle Oryzaephilus surinamensis L, the maize weevil, Sitophilus zeamais (Motsch) and the house fly, Musca domestica L. The fumigation LC50 values were calculated by probit analysis. For house flies, all but one of the cyanohydrins tested were more potent than 1,3-dichloropropene (Telone®). Three were as efficacious as chloropicrin. For the lesser grain borer, all cyanohydrins tested were more insecticidal than dichloropropene, and all but one were more potent than chloropicrin. Four were as insecticidal as dichlorvos. The acetate of 1-cyano-1-hydroxy-2-propene (CHP-ace) was also tested in soil for antifungal and antibacterial activity, and inhibition of weed seed germination. CHP-ace reduced the total soil bacterial and fungal counts significantly, and was effective in inhibiting the germination of weed seeds in soil, indicating a broad spectrum of activity as a soil fumigant. Copyright © 2004 Society of Chemical Industry [source]


Effect-site concentration of remifentanil attenuating surgical stress index responses to intubation of the trachea

ANAESTHESIA, Issue 6 2010
S. Mustola
Summary Surgical Stress Index has been proposed for assessment of surgical stress and analgesia. It is a numeric index based on the normalised pulse beat interval and photoplethysmographic pulse wave amplitude. We determined the effect-site concentration of remifentanil for attenuation of Surgical Stress Index responses to intubation of the trachea. Thirty ASA 1,2 patients received either deep or normal anaesthesia and then target-controlled remifentanil. Burst suppression was maintained in the deep group and state entropy at 40,60 (scale 0,91) in the normal group. Mean (SD) effect-site concentrations of remifentanil attenuating responses in 50% of patients were 2.13 (0.25) ng.ml,1 and 3.05 (0.27) ng.ml,1 in deep and normal groups, respectively (p = 0.034). From probit analysis, EC50 and EC95 of remifentanil (95% CI) were 2.34 (1.97,2.71) ng.ml,1 and 3.19 (2.69,3.69) ng.ml,1 in deep group and 3.17 (2.67,3.67) ng.ml,1 and 3.79 (3.21,4.37) ng.ml,1 in the normal group, respectively. The values from probit analysis and up-and-down method did not differ significantly. [source]


Effects of different doses of remifentanil on the end-tidal concentration of sevoflurane required for tracheal intubation in children

ANAESTHESIA, Issue 8 2009
L. He
Summary We investigated the effects of different doses of remifentanil on the end-tidal concentration of sevoflurane required for tracheal intubation in children without the use of neuromuscular blocking drugs. One hundred and thirty paediatric patients, aged 3,8 years, were randomly allocated to receive no remifentanil (group control) or remifentanil 0.1 ,g.kg,1.min,1 (group remi0.1), 0.2 ,g.kg,1.min,1 (group remi0.2), 0.3 ,g.kg,1.min,1 (group remi0.3). All patients were anaesthetised using 5% sevoflurane. After loss of eyelash reflex, remifentanil 1 ,g.kg,1 was injected over 1 min followed by an appropriate group-dependent infusion and the end-tidal sevoflurane concentration was changed. Predetermined end-tidal sevoflurane concentrations for each group were determined using the Dixon up-and-down method. After the target concentration of sevoflurane was maintained for 5 min, the child's trachea was intubated. Successful intubation was defined as excellent or good intubating conditions. The end-tidal concentration (SD) of sevoflurane for successful tracheal intubation in 50% of children (ED50) were 5.16 (0.22)% in control, 3.27 (0.18)%, 1.81 (0.20)% and 1.01 (0.11)%, in remi0.1, remi0.2, and remi0.3 groups, respectively. Using probit analysis, the 95% effective dose (ED95) of sevoflurane were 5.60% (95% CI 5.35,7.66), 3.77% (95% CI 3.45,7.74), 2.18% (95% CI 1.96,3.86), 1.19% (95% CI 1.06,1.82) in control, remi0.1, remi0.2, and remi0.3 groups, respectively. [source]


Optimal remifentanil dosage for providing excellent intubating conditions when co-administered with a single standard dose of propofol

ANAESTHESIA, Issue 7 2009
L. Bouvet
Summary This dose,response study aimed to determine the dose of remifentanil combined with propofol 2.5 mg.kg,1 which provided excellent intubation conditions in 95% of patients. Ninety premedicated female ASA 1 and 2 patients were randomly allocated to five remifentanil dose groups (1, 2, 3, 4 or 5 ,g.kg,1). Induction of anaesthesia was performed with a blinded dose of remifentanil infused over 60 s simultaneously co-administered with propofol 2.5 mg.kg,1 infused over 45 s. Tracheal intubation was attempted 150 s after the beginning of induction. Intubating conditions were assessed with the Copenhagen score. A probit analysis was performed to calculate the intubating efficient doses (IED) of remifentanil in 95% of patients (IED95). Our data revealed that the IED95 of remifentanil was 4.0 (95% CI: 3.4,5.6) ,g.kg,1, which was associated with a maximum decrease in heart rate and mean arterial pressure of < 30%, a finding which also applied to the other groups. [source]


Effect-site concentration of remifentanil for laryngeal mask airway insertion during target-controlled infusion of propofol

ANAESTHESIA, Issue 2 2009
M. K. Kim
Summary The purpose of this study was to determine the effect-site concentration of remifentanil that would provide optimal conditions for successful laryngeal mask airway insertion during a target-controlled infusion (TCI) of propofol at 3.5 ,g.ml,1 without the use of neuromuscular blockade. Five minutes after propofol infusion, remifentanil was infused at a dose determined by a modified Dixon's up-and-down method. Five minutes after remifentanil infusion, the laryngeal mask was inserted. The effect-site concentration of remifentanil for successful laryngeal mask insertion in 50% of adults (EC50) was 3.04 (SD 0.49) ng.ml,1 during a TCI of 3.5 ,g.ml,1 propofol without neuromuscular blockade. From the probit analysis, the EC50 and EC95 of remifentanil were 2.84 ng.ml,1 (95% CI 2.09,3.57 ng.ml,1) and 3.79 ng.ml,1 (95% CI 3.26,9.25 ng.ml,1), respectively. [source]


Disparities in the Emergency Department Evaluation of Chest Pain Patients

ACADEMIC EMERGENCY MEDICINE, Issue 2 2007
Liliana E. Pezzin PhD
Background The existence of race and gender differences in the provision of cardiovascular health care has been increasingly recognized. However, few studies have examined whether these differences exist in the emergency department (ED) setting. Objectives To evaluate race, gender, and insurance differences in the receipt of early, noninvasive diagnostic tests among persons presenting to an ED with a complaint of chest pain. Methods Data were drawn from the U.S. National Hospital Ambulatory Health Care Survey of EDs. Visits made during 1995,2000 by persons aged 30 years or older with chest pain as a reason for the visit were included. Factors affecting the likelihood of ordering electrocardiography, cardiac monitoring, oxygen saturation measurement using pulse oximetry, and chest radiography were analyzed using multivariate probit analysis. Results A total of 7,068 persons aged 30 years or older presented to an ED with a primary complaint of chest pain during the six-year period, corresponding to more than 32 million such visits nationally. The adjusted probability of ordering a test was highest for non,African American patients for all tests considered. African American men had the lowest probabilities (74.3% and 62% for electrocardiography and chest radiography, respectively), compared with 81.1% and 70.3%, respectively, among non,African American men. Only 37.5% of African American women received cardiac monitoring, compared with 54.5% of non,African American men. Similarly, African American women were significantly less likely than non,African American men to have their oxygen saturation measured. Patients who were uninsured or self-pay, as well as patients with "other" insurance, also had a lower probability than insured persons of having these tests ordered. Conclusions This study documents race, gender, and insurance differences in the provision of electrocardiography and chest radiography testing as well as cardiac rhythm and oxygen saturation monitoring in patients presenting with chest pain. These observed differences should catalyze further study into the underlying causes of disparities in cardiac care at an earlier point of patient contact with the health care system. [source]