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Data-centric applications are pushing the limits of energy-efficiency in today’s computing systems, including those based on phase-change memory (PCM). This technology must achieve low-power and stable operation at nanoscale dimensions to succeed in high-density memory arrays. Here we use a novel combination of phase-change material superlattices and nanocomposites (based on Ge 4 Sb 6 Te 7 ), to achieve record-low power density ≈ 5 MW/cm 2 and ≈ 0.7 V switching voltage (compatible with modern logic processors) in PCM devices with the smallest dimensions to date (≈ 40 nm) for a superlattice technology on a CMOS-compatible substrate. These devices also simultaneously exhibit low resistance drift with 8 resistance states, good endurance (≈ 2 × 10 8 cycles), and fast switching (≈ 40 ns). The efficient switching is enabled by strong heat confinement within the superlattice materials and the nanoscale device dimensions. The microstructural properties of the Ge 4 Sb 6 Te 7 nanocomposite and its high crystallization temperature ensure the fast-switching speed and stability in our superlattice PCM devices. These results re-establish PCM technology as one of the frontrunners for energy-efficient data storage and computing. Data-centric applications benefit from dense, low-power memory. Here the authors use a combination of chalcogenide superlattices and nanocomposites to achieve low switching voltage (0.7 V) and fast speed (40 ns) in 40-nm-scale phase-change memory.

INTRODUCTION:The incidence of cholangiocarcinoma is increasing worldwide. Over 8000 cases of both intrahepatic (ICC) and extrahepatic cholangiocarcinoma (ECC) are diagnosed every year in the US. Several recent studies have evaluated the role of non-fatty alcoholic liver disease (NAFLD) as a risk factor for cholangiocarcinoma. We performed a meta-analysis of case-control studies to evaluate the role of NAFLD as a risk factor for intrahepatic and extrahepatic cholangiocarcinoma.METHODS:We performed a systematic search of Medline, EMBASE and the Cochrane Library for studies without language restriction for case-control studies evaluating the risk of intra-hepatic and extra-hepatic cholangiocarcinoma in adult patients with NAFLD. We also hand searched grey literature from major gastrointestinal meetings. Standardized forms were used to extract data regarding number of cases of NAFLD and cholangiocarcinoma. Data was extracted by two reviewers independently. Summary odds ratio was calculated using Comprehensive Meta-analysis software. Heterogeneity, quality of studies and publication bias were also assessed. Random effects model was used for calculating the effect size.RESULTS:Ten studies met the inclusion criteria. 9 studies reported data on ICC and 5 studies reported data on ECC. Studies were performed in China, Taiwan, Japan, US, Europe and Korea. The period of patient enrollment ranged from 1992 to 2017. The majority of the studies used hospital based controls. The quality of the studies was assessed using Newcastle-Ottawa Scale. NAFLD was associated with a higher risk of ICC (OR 1.78: 95% CI 1.3–2.5, P = 0.001, I2 = 81). On subgroup analysis based on region of study, the increased risk was seen only in the studies reported from the Asian countries (5 studies, OR 1.93; 95% CI, 1.22–3.05, P = 0.005) but not from the Western countries (4 studies, OR 1.58; 95% CI 0.83–3.0, P = 0.17). On pooling all studies, risk of ECC was not increased in patients with NAFLD (OR 1.38; 95% CI 0.67–2.83, P = 0.55, I2 = 95%). However on subgroup analysis, increased risk of ECC was seen in the Western countries (2.42; 95% CI 2.01–2.91, P = 0.0001), but not the Asian countries. No significant publication bias was present.CONCLUSION:NAFLD is a risk factor for cholangiocarcinoma. Increased risk of ICC with NAFLD was seen in the Asian countries and ECC in the Western countries. Further studies are needed to confirm these findings.

INTRODUCTION:Post-polypectomy bleeding is a common complication of colonoscopy. Several endoscopic techniques including prophylactic endoscopic clip placement are used for prevention of post-polypectomy bleeding. However, several studies have reported mixed results on the efficacy of this approach. We conducted a meta-analysis of randomized controlled trials (RCTs) to assess the efficacy of prophylactic endoscopic clipping for prevention of delayed post-polypectomy bleeding.METHODS:Several databases (Embase, Pubmed, Cochrane database, Google Scholar) and abstracts of gastrointestinal and surgical meetings were searched extensively for relevant articles. Studies comparing prophylactic endoscopic clipping alone to standard colonoscopy with no endoscopic clipping were included. Studies that combined prophylactic clipping with other hemostatic techniques were excluded. Data was extracted using a standard form by two reviewers. Data regarding patient characteristics, types of polyps resected, post-polypectomy bleeding and other complications were extracted. Effect sizes were computed either using the fixed effects or random effects model using the Comprehensive Meta-analysis software. Publication bias, quality of studies and heterogeneity were analyzed.RESULTS:Nine RCTs were included in this study. The studies recruited subjects from USA, Japan, Canada and Spain. There were 3762 controls and 3658 patients in the treatment arm. Studies evaluated both small (<20mm) and large polyps (>20 mm), sessile and pedunculated polyps. The polyps were predominantly removed with standard polypectomy or endoscopic mucosal resection (for larger polyps). Delayed post-polypectomy bleeding occurred in 2.4% of controls and 1.6% in patients with endoscopic clipping. On analysis of all polyps, prophylactic endoscopic clipping decreased the risk of delayed post-polypectomy bleeding (RR = 0.71: 95% CI 0.51-0.99, P = 0.04, I2= 20%). The risk reduction was seen mainly with larger polyps(>20 mm), RR = 0.53 (95% CI : 0.32-.90, P = 0.02, NNT 28) and with sessile polyps (RR = 0.52, 95% CI: 0.32-0.83, P = 0.006, NNT 100). The protective effect was not seen for small polyps (<20 mm) (P = 0.91, P = 0.7) or pedunculated polyps (RR = 0.58, P = 0.29). All studies were of high quality. No publication bias or heterogeneity was present.CONCLUSION:Prophylactic clipping decreased the risk of delayed post-polypectomy bleeding. The benefit was mainly seen in patients with sessile polyps or large polyps (>20 mm).

INTRODUCTION:Several studies have reported increased risk of pancreatic cancer in patients with chronic pancreatitis. However, the risk of pancreatic cancer in patients with a history of acute pancreatitis (AP) is not well known. Several recent epidemiological studies, especially case-control studies, have reported conflicting results. We conducted a meta-analysis of cohort studies to quantify the risk of pancreatic cancer in patients with history of AP.METHODS:A detailed search of several databases (Pubmed, Embase, Google Scholar, Cochrane database and CINAHL) and research scientific meetings of gastroenterology and surgical societies was performed for cohort studies examining the risk of pancreatic cancer in patients with a prior history of acute pancreatitis. Data was extracted using a standard form by 2 reviewers. Data regarding study characteristics, patient characteristics, exposures and outcomes and country of study was extracted. Summary odds ratio was calculated using Comprehensive Meta-analysis software. Random effects model was used for computing effect size. Studies without a matched control group were excluded. Heterogeniety and publication bias were assessed. Quality of studies was assessed using the Newscastle-Ottawa scale. There were no language restrictions.RESULTS:Five cohort studies met the inclusion criteria. Studies were performed in UK, Sweden, USA and Taiwan. The most common etiology of AP was gall stone pancreatitis in all the studies. Patients with chronic pancreatitis and alcohol related acute pancreatitis were excluded in all studies. All studies had a matched control group and adjusted for confounders. There were 1162 cases of pancreatic cancer in 103958 patients with a prior history of acute pancreatitis. 2042 cases of pancreatic cancer were seen in 1442158 controls. A higher risk of pancreatic cancer was seen among patients with prior history of AP (OR 7.39: 95% CI 5.03–10.88, P < 0.05). Three studies provided data on risk of pancreatic cancer >2 years after diagnosis of AP. The risk of pancreatic cancer was still elevated after >2 years in patients with prior of history of AP (OR 2.31: 1.61 = 3.30, P < 0.05). Heterogeneity was present and the effect size was computed using random effects model.CONCLUSION:Patients with a prior history of AP are at an increased risk of pancreatic cancer. Further cohort studies are needed to confirm these findings.

INTRODUCTION:Percutaneous endoscopic gastrostomy (PEG) tube placement is associated with a risk of infection. It is currently a standard of practice to administer prophylactic antibiotics with PEG tubeplacement. However, several recent studies have reported mixed results. We performed an updated meta-analysis to assess the efficacy of prophylactic antibiotics for PEG tube placement.METHODS:MEDLINE, Google scholar, Embase PubMed, Cochrane Database, and abstracts from gastroenterology scientific meetings were searched. Only randomized controlled trials (RCTs) of adult subjects comparing prophylactic antibiotics to no prophylactic antibiotics for PEG tube placement were included. Study quality was accessed by assigning a quality score. Two independent reviewers used standard forms to extract data and the differences were resolved by mutual agreement. Meta-analysis for the effects of prophylactic antibiotics was analyzed by calculating pooled risk or odds ratio for peristomal infections, systemic infections, and mortality using both fixed and random effects models. Heterogeneity among studies was assessed by calculating I2 measure of inconsistency. Publication bias was also assessed.RESULTS:Thirteen RCTs (636 controls/764 treatment arm) met the inclusion criteria. All trials were published between 1985 and 2016. Eight trials predominantly used cephalosporins and 5 trials used penicillins. Eleven trials reported the technique of PEG tube placement: 8 used pull technique, 1 push technique, 1 both and 1 used the introducer method. In the treatment arm 1.07% of the patients got peristomal infection and in the control arm it was 2.55%. Prophylactic antibiotics with PEG tube placement resulted in a significant reduction in the risk of peristomal infection (RR 0.49, 95% CI: 0.39–0.63, P < 0.001, NNT = 8) and systemic infection. On subgroup analysis, both cephaloporins and penicillin based prophylaxis resulted in statistically significant reduction in risk of infections. Both single dose and multiple doses of antibiotics resulted in a reduction in the risk of infection. No significant difference was noted for mortality. Heterogeneity among studies was not significant. Funnel plots revealed no significant publication bias. Majority of the studies received a high score for quality.CONCLUSION:Current evidence supports the administration of prophylactic antibiotics prior to PEG tube placement. Further studies need to explore different PEG tube placement techniques that might obviate the need for antibiotics.

While Republicans are busy trying to deny Donald Trump their party's nomination, another group of conservative strategists is surely developing a more draconian backup plan: call it the Steal It In the House Option. What might have once seemed inconceivable is now entirely possible this fall: a presidential election decided not by the voters, not even by the Electoral College, but by as few as 26 state delegations in the House of Representatives.

MCI launched an advertising campaign in 1996 that was riddled with distortions, misleading information, and omissions. To help consumers sort through the rhetoric and confusion that MCI created, the US Telephone Association launched its own campaign called \"Consumers Beware. Exposed: How MCI's Advertising Is Misleading the Public.\" The group compiled all of MCI's print advertisements that ran from January 1, 1997 to April 3, 1997, and laid them side by side with the facts that refuted MCI's fictitious claims. Some of the misinformation that the US Telephone Association discovered is presented.

Sir, Your leader \"US phone mess\" (January 15), was deeply lacking in some basic facts. The intent of the 1996 Telecommunications Act was to foster real competition among the local telephone, long distance and cable industries. USlocal telephone companies strongly supported passage of the act, which promised more consumer choices, lower prices, technological advancement and increased competition in the US. The actions of the Regional Bell Operating Companies demonstrate this industry's unquestionable commitment to fostering real competition and ability to compete under fair terms.

  THE EDITORIAL PAGE; Today's debate: LOCAL PHONE RATES; OPPOSING VIEW: But AT&T and MCI are interested only in business and affluent residential areas. Two very recent events -- a federal appeals court judgment on the Federal Communications Commission's telephone interconnection order and the FCC's formation of a new local competition task force -- stand to greatly impact the advent of competition in the local telephone service market. Last Friday's reversal of the FCC's interconnection order by the 8th Circuit Court of Appeals in St. Louis validated what the local telephone companies of this nation have been saying all along: