Intrusion and extrusion of water in hydrophobic mesopores

We present experimental and theoretical results on intrusion-extrusion cycles of water in hydrophobic mesoporous materials, characterized by independent cylindrical pores. The intrusion, which takes place above the bulk saturation pressure, can be well described using a macroscopic capillary model. Once the material is saturated with water, extrusion takes place upon reduction of the externally applied pressure; Our results for the extrusion pressure can only be understood by assuming that the limiting extrusion mechanism is the nucleation of a vapour bubble inside the pores. A comparison of calculated and experimental nucleation pressures shows that a proper inclusion of line tension effects is necessary to account for the observed values of nucleation barriers. Negative line tensions of order $10^{-11} \mathrm{J.m}^{-1}$ are found for our system, in reasonable agreement with other experimental estimates of this quantity

Treatment of primary varicose veins by endovenous obliteration with the VNUS closure system: Results of a prospective multicentre study

Background. Radio frequency obliteration of the saphenous veins has been introduced as a less invasive alternative to traditional surgery for varicose veins. Objective. To report the efficacy of obliteration and clinical outcomes following endovenous obliteration of the saphenous vein with limited follow-up to 3 years. Materials and methods. Radiofreq uency obliteration (Closure® system, VNUS Medical Technologies, San Jose, CA) was performed in 330 limbs of 294 patients in a prospective worldwide multicentre study with 31 participating sites. Follow-up duplex ultrasound and clinical examinations were performed at annual intervals. The main outcome measures were the completeness of occlusion of the treated vein segment, presence of reflux and presence of signs and symptoms of venous disease. Results. Before treatment 3.9% of limbs were categorised as CEAP clinical class zero or one. This improved to 82.9% at 1 year, 83.1% at 2 years and 86.8% at 3 years following treatment. Varicose vein free rates were 1 year: 90.1%, 2 years: 87.2%, 3 years: 88.2%. Duplex ultrasound demonstrated a reflux-free rate of about 88% over 3 years. Total occlusion (TO) of veins was 1 year: 81%, 2 years: 80.4% and 3 years: 75%. Partial occlusion (PO, 5 cm open segment) was 1 year: 12.7%, 2 years: 12.2% and 3 years: 7.4%. Partial occlusion did not result in any differences in the symptom severity score, the number of symptom free limbs, or the varicose vein absence rates at any follow-up time point when compared to the total occlusion group. The varicose vein absence rates were significantly lower in the IO group comparing to the TO and PO groups. Conclusions. Radiofrequency saphenous vein obliteration improves the symptoms of varicose veins. The reflux-free rates in the treated veins remain constant over a 3 year follow-up period. There is no difference in clinical outcomes between the TO and the PO limbs, suggesting clinical effectiveness of the PO category. Greater than a 5 cm open segment in treated veins poses a risk of recurrence. © 2004 Elsevier Ltd. All rights reserved

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially