Caecal disease in equids

OBJECTIVE: To review the breed, age, gender, clinical and laboratory findings, treatment and outcome of horses with caecal disease presented to a referral centre. DESIGN: Retrospective study of 96 cases. PROCEDURE: The breed, age, and gender of the study population were compared with the corresponding hospital population for the same period. The means (+/- SD) for clinical and laboratory findings were recorded for each caecal disorder. Treatment was categorised as medical or surgical, and outcome was recorded. RESULTS: Caecal diseases included impaction (40% of total cases), rupture associated with concurrent unrelated disease (13%), rupture with parturition (9%), rupture with no associated disease (5%), infarction (11%), torsion (9%), abscess or adhesion (7%), tumour (3%), and miscellaneous conditions (3%). The breed or gender of affected horses did not differ from the hospital population, although horses > 15 years were more frequently represented (P < 0.05). This age group was specifically more predisposed to caecal impaction (P < 0.05), as were Arabian, Morgan, and Appaloosa breeds (P < 0.05). In horses with caecal impaction transrectal examination was the most useful diagnostic procedure; 90% of affected horses treated medically were discharged while horses treated by typhlotomy alone, or typhlotomy and blind end ileocolostomy, had survival rates to discharge of 71% and 86%, respectively. Horses with caecal rupture associated with concurrent un-related disease showed no signs of impending rupture; all were receiving phenylbutazone, all were euthanased, and 50% had caecal ulceration at necropsy. Of horses with caecal rupture with parturition 56% had prior dystocia; in two-thirds the site of rupture was the ileocaecal junction and all were euthanased. Horses with caecal rupture with no associated disease died or were euthanased; rupture was idiopathic. Horses with caecal infarction usually had signs of abdominal pain and abdominal fluid changes consistent with peritonitis; transrectal examination was nonspecific, and typhlectomy was successful in seven of eight horses. Horses with caecal torsion had signs of severe, acute abdominal pain and typhlectomy was successful in three of five horses. Diagnosis of caecal adhesion or abscess was assisted by transrectal palpation in two of seven horses and surgical treatment was successful in two of five horses. A caecal tumour was diagnosed in three horses aged 20 years or older that presented with chronic weight loss. Other caecal diseases were uncommon. CONCLUSION: Caecal disease is uncommon in equids but some specific features of the history and physical findings can alert the veterinarian to the possibility of caecal involvement in horses with gastrointestinal dysfunction. Medical or surgical therapy can be effective in horses where caecal rupture has not occurred.     

Quantitative effects of acquisition duration and temporal resolution on the measurement accuracy of prostate dynamic contrast-enhanced MRI data: a phantom study

Objectives

The aim of this study was to investigate the effect of the temporal resolution (T _res) and acquisition duration (AD) on the measurement accuracy of contrast concentration–time curves (CTCs), and derived phenomenological and pharmacokinetic parameter values, in a dynamic contrast-enhanced MRI experiment using a novel phantom test device.

Materials and methods

‘Ground truth’ CTCs were established using a highly precise optical imaging system. These precisely known CTCs were produced in an anthropomorphic environment, which mimicked the male pelvic region, and presented to the MRI scanner for measurement. The T _res was varied in the range [2–24.4 s] and the AD in the range [30–600 s], and the effects on the measurement accuracy were quantified.

Results

For wash-in parameter measurements, large underestimation errors (up to 40%) were found using T _res values ≥16.3 s; however, the measured wash-out rate did not vary greatly across all T _res values tested. Errors in derived K ^trans and v _e values were below 14 and 12% for acquisitions with {T _res ≤ 8.1 s, AD ≥ 360 s} and {T _res ≤ 16.3 s, AD ≥ 360 s}, respectively, but increased dramatically outside these ranges.

Conclusions

Errors in measured wash-in, wash-out, K ^trans, and v _e parameters were minimised using T _res ≤ 8.1 s and AD ≥ 360 s, with large errors recorded outside of this range.

     

Response of reinforced concrete beams to hydrostatic pressure acting within primary cracks

This paper investigates the response of reinforced concrete beams to hydrostatic pressure acting within primary cracks. Notched beams were initially pre-cracked before pressurised water was introduced into the primary crack. The deflection and strain increase at tensile reinforcement level (due to the pressurised water load) was measured. Tests were carried out using applied hydrostatic pressures of 0.2 and 0.325 MPa. Results show that both deflection and strain at tensile reinforcement level increases immediately after the introduction of hydrostatic pressure into open primary cracks. If the crack is held open and hydrostatic pressure is allowed to build up within the depth of the crack, additional deformation occurs. A finite element (FE) model was constructed to investigate the effects of greater hydrostatic pressures acting within the primary crack. The FE model was first validated against the test data, before being used to assess the structural response of the reinforced concrete section to applied hydrostatic pressures of up to 1 MPa. It was found that section deformations increased as hydrostatic pressure was increased. At applied hydrostatic pressures of 0.8 MPa and above, the increases in strain at tensile reinforcement level were shown to be significant. DNV-0S-C205, which is the Det Norske Veritas (DNV) standard for offshore concrete structures states that the ‘effects of water pressure within cracks may be neglected for structural elements exposed to less than 100 m (0.981 MPa) of water head.’ The current research suggests that the effects of water pressure within cracks for structural elements exposed to slightly less than 100 m water head may also be significant (based on a 10 % threshold criteria). However, it is accepted that a more comprehensive parametric study would be required to determine whether or not the DNV should be redressed.     

Partially observed epidemics in wildlife hosts: modelling an outbreak of dolphin morbillivirus in the northwestern Atlantic,June 2013–2014

Morbilliviruses cause major mortality in marine mammals, but the dynamics of transmission and persistence are ill understood compared to terrestrial counterparts such as measles; this is especially true for epidemics in cetaceans. However, the recent outbreak of dolphin morbillivirus in the northwestern Atlantic Ocean can provide new insights into the epidemiology and spatio-temporal spread of this pathogen. To deal with uncertainties surrounding the ecology of this system (only stranded animals were observed), we develop a statistical framework that can extract key information about the underlying transmission process given only sparse data. Our self-exciting Poisson process model suggests that individuals are infectious for at most 24 days and can transfer infection up to two latitude degrees (220 km) within this time. In addition, the effective reproduction number is generally below one, but reaches 2.6 during a period of heightened stranding numbers near Virginia Beach, Virginia, in summer 2013. Network analysis suggests local movements dominate spatial spread, with seasonal migration facilitating wider dissemination along the coast. Finally, a low virus transmission rate or high levels of pre-existing immunity can explain the lack of viral spread into the Gulf of Mexico. More generally, our approach illustrates novel methodologies for analysing very indirectly observed epidemics.     

Diffusion-controlled reference material for volatile organic compound emissions testing: Pilot inter-laboratory study

To improve the reliability and accuracy of tests used to measure emissions of volatile organic compounds (VOCs) from samples of interior building products, the National Institute of Standards and Technology (NIST) and Virginia Tech (VT) have created a program to develop reference materials with independently predictable emission rates. A diffusive reference material and associated mechanistic model have been developed and are undergoing extensive evaluation. As part of this process, a pilot inter-laboratory study (ILS) was conducted with four laboratories using a polymer material loaded with toluene as the reference source. Results showed the prototype material to be a relatively stable, homogeneous source with consistent emissions both within and between production batches. A comparison of toluene emission rates determined by the laboratories showed relative standard deviations as low as 9%, which are significantly lower than inter-laboratory variations for most previous ILS exercises with VOC sources. At a sample time of 48 h, the mean measured toluene emission rate for all four laboratories was within 1% of the model predicted value. The success of this pilot ILS is a key step toward being able to provide a VOC reference material for independent validation of VOC emission tests conducted in small chambers.     

Issues in the development of reliable measures in addiction research: Introduction to Project MATCH assessment strategies.

This article provides an introduction to the 5 instrument articles in this special section, each of which presents a psychometric evaluation of a self-administered questionnaire developed for use in addictions treatment research. An overview of measurement theory is presented, and social-psychological factors that affect reliability and validity are considered. The instruments evaluated in this issue are summarized, and the 2 common data sources for the 5 reports, the Project MATCH baseline data set and the Project MATCH Reliability Study, are described. The article concludes with a brief summary that offers recommendations regarding how psychometric investigation should be undertaken and applied to the development of self-report questionnaires in addictions research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Continuous cooling deformation testing of steels

In the processing of steel, the design of any kind of heat treatment and/or thermomechanical processing schedule, to obtain a given microstructure, is greatly facilitated by the knowledge of the austenite-to-ferrite transformation characteristics. In the past, isothermal and continuous cooling tests were used in the laboratory to create time-temperature-transformation and continuous cooling transformation diagrams, respectively, which then served as the source of transformation data. The problem with such information is that it is only truly applicable to one particular microstructure, usually one resulting from a simple reheating cycle in the austenite region. Most industrial steel processing operations additionally involve several stages of high-temperature deformation leading to changes in the microstructure emerging from the final pass. To account for this situation, a novel laboratory method for the determination of the transformation characteristics, based on continuous cooling deformation testing, was developed. A major attraction of this test technique is that the specific microstructure, for which the transformation characteristics are required, can be generated by hot deformation and then immediately evaluated by continuous cooling deformation. In this article, the basic continuous cooling deformation test technique and general methods of data analysis are illustrated, using results from several different grades of steel. Formerly with the Department of Mining and Metallurgical Engineering, McGill University     

Flow diagram or prose: does the format of practice guidelines matter?

BACKGROUND: Hematopoietic and organ transplantations are increasing worldwide with more patients receiving immunosuppressive therapy. Neurological problems may complicate the posttransplant period. Possible causes include the conditioning regimen (e.g., seizures with busulfan), central nervous system infections (viral, bacterial, and fungal), or factors secondary to the immunosuppressive therapy and side effects of drug treatment (e.g., cyclosporine and tacrolimus). Sinus venous thrombosis, the occlusion of a cerebral venous vessel or a sinus, is an unusual cause of neurologic symptoms in patients after transplantation, and this has not been reported in the literature previously. METHODS: Three patients presenting with various neurological symptoms after allogeneic bone marrow transplantation underwent computed tomography scans and magnetic resonance imaging as a primary diagnostic procedure. RESULTS: In all patients, sinus venous thrombosis was found as the cause for seizures; it was the cause of disturbance of consciousness in two patients and headaches in two patients. All symptoms resolved without any neurologic deficiency after anticoagulation therapy with heparin followed by dicumarol. CONCLUSION: We conclude that sinus venous thrombosis should be considered as a cause of neurological symptoms in patients after transplantation under immunosuppressive therapy. Diagnosis is rapidly confirmed by noninvasive magnetic resonance imaging angiography. Therapeutic heparinization is the treatment of choice.     

Rheological behaviour and related granulometric properties of dense aggregated suspensions during an ultrafine comminution process

The rheological behaviour of calcite suspensions made of particles with different size distributions, obtained by means of a wet comminution process, have been studied versus the operating conditions (volume concentration, use of dispersing agent). The suspension properties (size distribution, specific surface area [SSA]) were investigated in order to characterize the microstructure of the aggregated suspensions. The suspension acts as a thinning fluid with a yield value, and the viscosity increases when the particle size decreases (colloidal dispersions) due to attractive interparticle forces. The use of a polyelectrolyte (sodium polyacrylate [SPA]) during the size-reduction process allows strong reduction of the viscosity of the ground suspensions. The polymer is adsorbed onto the surface of the particles and, consequently, prevents aggregation and allows improvement of the process efficiency.     

Protective and risk factors in health-enhancing behavior among adolescents in china and the United States: Does social context matter?

An explanatory model of adolescent health-enhancing behavior based on protective and risk factors at the individual level and in 4 social contexts was used in a study of school-based samples from the People's Republic of China (n = 1,739) and the United States (n = 1,596). A substantial account of variation in health-enhancing behavior--and of its developmental change over time--was provided by the model for boys and girls, and for the 3 grade cohorts, in both samples. In both samples, social context protective and risk factors accounted for more unique variance than did individual-level protective and risk factors, and context protection moderated both contextual and individual-level risk. Models protection and controls protection were of particular importance in the explanatory account. (PsycINFO Database Record (c) 2010 APA, all rights reserved)