The effect of the digital printing of fabric on the morphology of passive bloodstains.

Bloodstained fabrics found at crime scenes are likely to have had processing treatments, such as dyeing or printing, but the effect of the treatments on bloodstain morphology is not always considered. In order to study the effect of digital printing on bloodstain morphology, drip stains were created from five impact velocities (1.9-5.4 ms-1) on three different mass per unit areas (88-226 g/m²) of 100% cotton calico which had been digitally printed using reactive dye. Across all three printed fabrics, the bloodstains appeared visually similar, and no correlation was found between the dry bloodstain area and the impact velocity. When comparing the bloodstains on the printed fabric to those which had been created previously on the same fabric in a dyed and not-coloured state, the dry bloodstains on the printed fabric were statistically significantly larger (e.g. for the calico with the lightest mass per unit area, mean dry bloodstain area was 126.6, 64.4 and 44.3 mm² for the printed, dyed and not-coloured fabrics respectively). Examination of the larger bloodstains on the printed calico with the micro computed tomography scanner and scanning electron microscope, suggested that the printing process increased the wettability of the fabric, so the blood could spread more easily on the surface. This allowed the blood to coat the yarns, and wick into them before wicking along the intra-yarn spaces. The results presented in this paper showed that care must be taken when examining bloodstains at crime scenes. Depending on the fabric and the processing of the fabric the size of the blood stains may not increase with impact velocity as wicking may result in a larger bloodstain from a lower velocity. The bloodstain on the penetrated face of the fabric may be larger than on the impacted face and the same fabrics with different processing will produce different blood stain sizes and shapes.

The effect of reactive dyeing of fabric on the morphology of passive bloodstains.

The majority of fabrics at crime scenes have been coloured in some way. The effect of such treatments on resultant bloodstains has not been considered. In this work, horse blood was dropped onto reactively dyed calico fabrics (100% cotton, plain woven) with three different masses of 91 g m-², 171 g m-² and 243 g m-² and the results compared to previous work on the not-coloured calico fabric. Five impact velocities were used from 1.7 ms-1 to 5.4 ms-1. The use of reactive dye increased the thickness (from 0.38 - 0.56 mm to 0.39 - 0.6 mm) and mass per unit area (from 85.1 - 224.6 g/m² to 91 - 243 g/m²) of the calico fabrics. The reactively dyed fabrics had larger bloodstains (e.g. lightest calico 41.2 - 78.6 mm²) compares to the not-coloured fabrics (e.g. lightest calico 21.4 - 67.5 mm²) across all three mass per unit areas. The dyeing of the fabrics altered the intra-yarn spaces to a more optimum size for wicking blood, increasing the ease with which the blood could wick along the yarns in the dyed calico. The amount of wicking varied depending on individual variations within the fabrics and yarns. More variation in dry bloodstain area was seen among dyed calico specimens than for the not-coloured fabric. The amount of wicking which was seen on the dyed calico meant there was no correlation between dry bloodstain area and impact velocity, a correlation which was seen on the medium and heavy not-coloured calico in the previous work.

Investigating bloodstain dynamics at impact on the technical rear of fabric.

Using high speed video, the impact of blood drops falling at three velocities (1.9, 4.2 and 5.8ms-1) were filmed from both the technical face and for the first time the technical rear of three different mass per unit areas (85.1, 163.5 and 224.6g/m²) of 100% cotton calico. It was seen that there were two stages in the creation of a bloodstain on fabric; the impact dynamics, followed by wicking along the intra-yarn spaces. In the first stage, once the blood impacted the fabric, blood was visible on the technical rear of the fabrics with the medium and lightest mass per unit area within as little as 0.067ms after impact. No blood was visible on the technical rear of the fabric with the heaviest mass per unit area following impact or the medium mass per unit area from 1.7ms-1 impacts. On the technical face of the fabric, the blood drop spread laterally and then receded for 8ms following impact. The dynamics on the technical face were not affected by what was occurring on the technical rear of the fabric. The bloodstain on the technical rear initially only increased until 0.8ms following impact. The increase in technical rear bloodstain area was caused by continued movement of the blood through to the rear of the fabric as the blood drop spread on the technical face. Once the impact dynamics were concluded within 8ms of impact, there was no further change in the bloodstain for the remaining 67ms of high speed video. Following this the blood wicked into and along the yarns, resulting in a dry technical rear bloodstain on all fabrics at all velocities.

The effect of fabric mass per unit area and blood impact velocity on bloodstain morphology.

This paper discusses the effects of thickness, mass per unit area, sett, yarn linear density and twist of calico fabrics (100% cotton, plain woven) on the morphology of passive bloodstains. Horse blood was dropped vertically onto three calico fabrics with different mass per unit areas (85.1 g/m², 163.5 g/m² and 224.6 g/m²). Six different impact velocities were used (1.7 ms-1, 2.9 ms-1, 4.1 ms-1, 4.9 ms-1, 5.1 ms-1 and 5.4 ms-1). The dry bloodstains were largest on the calico with the lightest mass per unit area. The low yarn linear density and large inter-yarn spaces meant that the blood could wick into the yarns from all directions and along the intra-yarn spaces. The calico with the middle mass per unit area had the smallest mean dry bloodstain area for four out of the six velocities. The twist level for this calico was greater than for the calicos with a heavier or lighter mass per unit area. This reduced the amount of wicking which occurred along the yarns due to the tighter yarn structure. The calico with the heaviest mass per unit area had the highest yarn linear density resulting in a thicker fabric, so the blood could not as easily penetrate into the fabric. This resulted in a thicker wet blood layer remaining on the fabric surface, where it gradually wicked vertically into the yarns under gravity. Less wicking along the yarns occurred, resulting in a smaller bloodstain than on the fabric with the lightest mass per unit area. The correlation between impact velocity and mean dry bloodstain area was greater for the calicos with the medium and heaviest mass per unit area than for the calico with the lightest mass per unit area. For the calicos with the medium and heaviest mass per unit area, the distance the blood spread laterally at impact, which increased with the increase in impact velocity, had a greater influence on the dry bloodstain area than the amount of wicking.

The use of micro computed tomography to ascertain the morphology of bloodstains on fabric.

Very little is known about the interactions of blood and fabric and how bloodstains on fabric are formed. Whereas the blood stain size for non-absorbent surfaces depends on impact velocity, previous work has suggested that for fabrics the blood stain size is independent of impact velocity when the drop size is kept constant. Therefore, a greater understanding of the interaction of blood and fabric is required. This paper explores the possibility of using a micro computed tomography (CT) scanner to study bloodstain size and shape throughout fabrics. Two different fabrics were used: 100% cotton rib knit and 100% cotton bull drill. Bloodstains were created by dropping blood droplets from three heights; 500 mm, 1000 mm and 1500 mm. Results from the CT scanner clearly showed the bloodstain shape throughout the fabric. The blood was found to form a diamond shaped stain, with the maximum cross-sectional area 0.3-0.5mm below the surface. The bloodstain morphology depended on both the impact velocity and fabric structure.

Training students in education of the hypertensive patient: enhanced performance after a simulated patient instructor (SPI)-based exercise.

The process whereby a physician explains to the ill patient what has gone wrong and what can be done about it can be taught and evaluated by simulated patients (SPIs). This study was designed to determine whether a training experience in educating a diabetic SPI improves subsequent performance with a hypertensive SPI. Competence in educating a hypertensive SPI by students who had no prior training experience (n = 26) was compared to that of an experimental group (n = 20) that had a prior training session. Performance was assessed with a counseling skills scale and a case-specific content checklist (1 = poor to 5 = excellent). Students in the experimental group performed better than controls in both counseling skills (4.46 v 3.86, P < .01) and completeness of coverage of content (3.28 v 2.65, P < .01). Students in both groups focused more on clinical features and treatment than on laboratory testing and follow-up. The ability to counsel "patients" with hypertension can be enhanced by a prior learning experience with a diabetic SPI. Clinical application of knowledge about hypertension can be assessed by SPIs.

Teaching smoking-cessation counseling to medical students using simulated patients.

OBJECTIVE: Our objective was to evaluate the effectiveness of using simulated patient instructors and the Ockene method to instruct third-year medical students in smoking-cessation counseling techniques. DESIGN: We used a clinical exercise with self-study preparation and simulated patient instructors. METHODS: One hundred fifty-nine students participated in a smoking-cessation counseling session in which cognitive and behavioral endpoints were assessed by simulated patient instructors and the students themselves. RESULTS: Student performance in the cognitive and behavioral components of model smoking-cessation counseling was acceptable. Specific areas of weakness, such as the tendency of students to underemphasize the personal and social benefits of smoking cessation, and to overestimate their competence on a number of skill items, were identified. Student evaluation of the exercise was positive. CONCLUSIONS: Smoking-cessation counseling can be taught effectively to third-year medical students by simulated patient instructors during a clinical clerkship.

The effect of a standardized patient instructor experience on students' anxiety and confidence levels performing the male genitorectal examination.

BACKGROUND: Standardized patient instruction (SPI) is recommended as a nonthreatening method for teaching the male genitorectal examination. The article's purpose is to describe the method's effectiveness in reducing anxiety and increasing confidence among men and women students from diverse cultures. DESCRIPTION: We implemented an SPI program in 1993 to teach the examination to 2nd-year students. Students performed their examinations in mixed gender groups of three; a man student was responsible for disrobing the SPI and performing the first exam. During the 45-min session, each of the three students performed the examination in turn, and each received immediate feedback on their technique and interpersonal approach to the patient. EVALUATION: All students (n = 190) evaluated their SPI encounter immediately after the session had ended. CONCLUSIONS: Men and women students from all ethnic groups reported decreased anxiety and increased confidence levels after the SPI session. These findings indicate that a carefully orchestrated SPI session is effective in reducing students' anxiety about crossing personal space boundaries, overcoming a variety of proscriptions on gender-appropriate interactions, and increasing their confidence to perform this sensitive examination.

Translational fusions with fragments of the trpE gene improve the expression of a poorly expressed heterologous gene in Escherichia coli.

A series of plasmids expressing fusions between the trpE gene product, anthranilate synthase component I and the major immunogen (VP1) of foot and mouth disease virus were constructed such that increasing amounts of the 3' end of trpE were deleted. Deletions removing up to 70% of trpE had little effect on the quantity of fusion protein expressed, while the number of molecules appeared to increase. Larger deletions led to a steady decrease in both the quantity of fusion protein produced and in the number of molecules. This is consistent with trpE being responsible for the high levels of expression of VP1 by its gene product stabilizing VP1 against proteolytic degradation. Some out-of-frame deletion mutants were also produced. All deletion mutants in one wrong reading frame expressed low levels of two VP1-containing polypeptides. This observation is interpreted as being due to re-initiation of translation at a site inside the VP1 sequence which is activated by local termination of translation.