Physical Realization of Elastic Cloaking with a Polar Material.

An elastic cloak is a coating material that can be applied to an arbitrary inclusion to make it indistinguishable from the background medium. Cloaking against elastic disturbances, in particular, has been demonstrated using several designs and gauges. None, however, tolerate the coexistence of normal and shear stresses due to a shortage of physical realization of transformation-invariant elastic materials. Here, we overcome this limitation to design and fabricate a new class of polar materials with a distribution of body torque that exhibits asymmetric stresses. A static cloak for full two-dimensional elasticity is thus constructed based on the transformation method. The proposed cloak is made of a functionally graded multilayered lattice embedded in an isotropic continuum background. While one layer is tailored to produce a target elastic behavior, the other layers impose a set of kinematic constraints equivalent to a distribution of body torque that breaks the stress symmetry. Experimental testing under static compressive and shear loads demonstrates encouraging cloaking performance in good agreement with our theoretical prediction. The work sets a precedent in the field of transformation elasticity and should find applications in mechanical stress shielding and stealth technologies.

Roux-en-Y Gastric Bypass Versus One Anastomosis Gastric Bypass as Revisional Surgery After Failed Sleeve Gastrectomy: A Systematic Review and Meta-analysis

Purpose@#This study aimed to assess the outcomes of revisional procedures, namely Roux-en-Y gastric bypass (RYGB) and one anastomosis gastric bypass (OAGB) following unsuccessful laparoscopic sleeve gastrectomy. @*Materials and Methods@#This systematic review and meta-analysis included 817 patients (404 in OAGB group, 413 in RYGB group) from seven retrospective comparative studies. Data on sample size, demographics, perioperative complications, operative time, pre- and post-revisional body mass index, total weight loss, and global weight loss over follow-up were extracted. @*Results@#The mean operative time was 98.2–201 minutes for RYGB versus 78.7–168 minutes for OAGB. Despite classical RYGB gastric bypass taking longer, mini gastric bypass resulted in greater weight loss than RYGB, with a mean difference of −5.84 (95% confidence interval [CI], −6.74 to −4.94; P<0.00001; I 2 =0%), greater total weight loss, and a higher diabetes remission rate (odds ratio [OR], 0.32; 95% CI, 0.14 to 0.71). However, OAGB was associated with a significantly higher incidence of postoperative gastroesophageal reflux than RYGB (52 vs. 31: OR, 0.40; 95% CI, 0.24 to 0.67; P=0.0005; I 2 =0%). @*Conclusion@#OAGB was performed more quickly and boasted greater total weight loss and higher diabetes remission rates compared to RYGB after failed sleeve gastrectomy. However, OAGB also demonstrated a higher incidence of postoperative gastroesophageal reflux disease. Thus, careful patient selection is essential when considering OAGB.

Assessing the Lebanese population for their knowledge, attitudes and practices of antibiotic usage

Antibiotic-resistant bacteria has become a global phenomenon, mainly due to the inappropriate use of antibiotics. There are no studies in Lebanon to assess the public's knowledge, attitudes and practices [KAP] of antibiotic usage. A cross-sectional study was carried out using a self-administered questionnaire completed by a random convenience sample of 500 people. Nearly half of the respondents [46.1%] demonstrated moderate knowledge levels, while 40.6% demonstrated moderate attitudes. Although 80.2% knew that antibiotics are anti-bacterial, 73.5% did not know that antibiotics are not anti-viral. Moreover, 68.3% of respondents reported consuming antibiotics 1-3 times per year, while 22.4% consumed antibiotics on their own accord. Approximately 66.7% realized that abusing antibiotics could lead to resistance. Participant knowledge and attitudes were significantly associated with monthly family income, educational level, place of residency, having medical insurance, working in the health sector or having a relative working in the health sector. Nation-wide awareness campaigns targeting susceptible demographics should be initiated

High vacuum phacoemulsification technique in cataract surgery

Phacoemulsification offers the advantage of cataract removal through a small wound which decreases the surgical complications and enhances rehabilitation. In phacoemulsification corneal endotlielial loss was correlated to duration of ultrasound power used. The longer the duration, the greater is the loss . Increasing the power carries the risk of increasing the insult. While decreasing the power causes less effective cutting power and more stress on capsule and zonules. Vacuum is one of the tools that can be used in phacoemulsification. It can be used as a holding power at probe port for efficient cutting. It also, aspirates soft materials and therefore reduces the need for ultrasound power. To evaluate the use of high vacuum while performing phacoemulsification and to correlate the ultrasonic power needed in relation to the vacuum level. Forty patients with 40 cataractous eyes were enrolled in this study. Their ages ranged between 53 to 65 years with a mean of 59 +/- 6.5 years. Patients were divided into two groups each containing 20 patients [eyes]. Group I underwent phacoemulsification cataract extraction with posterior chamber [PC] foldable acrylic lens using the highest possible vacuum and accordingly lowest possible ultrasound power. Group II underwent traditional phacoemulsification cataract extraction with posterior chamber [PC] foldable acrylic lens. In both groups phacoemulsification was performed in-situ using stop and chop technique. The viscoelastic substance that had been used was sodium hyalurinate [Healon]. Central corneal ultrasound pachymetry was done for all patients preoperatively. Postoperatively; patients were examined weekly in the first postoperative month then after second and third month where central corneal pachymetry was done in each visit. These pachymetric values were used as a sensitive indicator of corneal endothelial physiology. The ultrasound powers and times used in emulsification were recorded during surgeries to correlate them to the vacuum. Postoperatively; the corneal thickness had been increased in all patients due to corneal edema. This corneal edema continued to improve during the 3 months follow up period. The corneal edema postoperatively was less in group I than in group II. With the high vacuum; the ultrasound power needed was less that that needed with traditional vacuum levels. The ultrasound energy [Power x Time] was inversely proportional to the vacuum used. From our study we can conclude that using the highest possible vacuum while doing phacoemulsification is a good tool that allows the use of lower ultrasound power. This lower ultrasonic power is safer for the corneal endothelium. Thus; the final visual outcome of the phacoemulsification cataract surgery can be refined

Strategies for myocardial protection during cardiopulmonary by-pass in congenital cyanotic heart disease guided by troponin I

Forty cyanotic infants with age ranging from six to 24 months and body weights ranged from six to 11 kg were included in this study and the surgical correction of their congenital cardiac problems was done under cardiopulmonary bypass. The selected cases were divided into four equal groups according to the concentration of KCl added to the blood cardioplegia and the intravenous administration of aprotinin. In group A, 30 mEq KCl/L was added to the blood cardioplegic solution. In group B, 40 mEq KCl/L was added to the blood cardioplegic solution. In group C, together with blood cardioplegia as group A, the patients received intravenous high dose regimen of aprotinin. In group D, the patients received the same intravenous regimen of aprotinin as group C, but with blood cardioplegia as group B. The serum level of cardiac troponin I [cTnI] was assessed as an index of myocardial injury simultaneously with serum sodium, potassium and calcium. These variables were measured in different periods of the study, starting from period I [baseline value, before induction of anesthesia] and ending by period VII [after the transfer to intensive care unit]. The total dosage of inotropic supporters [adrenaline and dopamine], vasodilators [sodium nitroprusside] and myocardial behavior were monitored in all studied cases. The study concluded that the intravenous administration of the high dose regimen of aprotinin with the addition of 40 mEq/L KCl to the blood cardioplegic solution was one of the best strategies for myocardial protection during cardiopulmonary bypass in cyanotic infants