The diameter of the world wide web

Despite its increasing role in communication, the world wide web remains the least controlled medium: any individual or institution can create websites with unrestricted number of documents and links. While great efforts are made to map and characterize the Internet's infrastructure, little is known about the topology of the web. Here we take a first step to fill this gap: we use local connectivity measurements to construct a topological model of the world wide web, allowing us to explore and characterize its large scale properties.Comment: 5 pages, 1 figure, updated with most recent results on the size of the ww

Massive MIMO Systems With Low-Resolution ADCs: Baseband Energy Consumption vs. Symbol Detection Performance

In massive multiple-input multiple-output (MIMO) systems using a large number of antennas, it would be difficult to connect high-resolution analog-to-digital converters (ADCs) to each antenna component due to high cost and energy consumption problems. To resolve these issues, there has been much work on implementing symbol detectors and channel estimators using low-resolution ADCs for massive MIMO systems. Although it is intuitively true that using low-resolution ADCs makes it possible to save a large amount of energy consumption in massive MIMO systems, the relationship between energy consumption using low-resolution ADCs and detection performance has not been properly analyzed yet. In this paper, the tradeoff between different detectors and total baseband energy consumption including flexible ADCs is thoroughly analyzed taking the optimal fixed-point operations performed during the detection processes into account. In order to minimize the energy consumption for the given channel condition, the proposed scheme selects the best mode among various processing options while supporting the target frame error rate. The numerous case studies reveal that the proposed work remarkably saves the energy consumption of the massive MIMO processing compared with the existing schemes.11Ysciescopu

Relationships between 24-Hour Blood Pressures, Subcortical Ischemic Lesions, and Cognitive Impairment

Background and Purpose The most important treatment for subcortical vascular dementia (SVaD) is controlling the blood pressure (BP). However, the few studies that have investigated the relationships between diurnal BP rhythm and subcortical ischemic vascular cognitive impairment have produced inconclusive results. In the study presented here, the 24-hour BP values of three groups of subjects-patients with subcortical vascular mild cognitive impairment (SvMCI), patients with SVaD, and normal controls-were compared using working criteria and 24-hour ambulatory BP (ABP) monitoring. Methods The subjects (42 patients with SVaD, 37 patients with SvMCI, and 30 controls) were selected according to the Study`s inclusion/exclusion criteria. All subjects underwent brain magnetic resonance (MR) imaging and MR angiography, detailed neuropsychological testing, and 24-hour ABP monitoring. Results The prevalence of nondippers differed markedly between the control group and both the SVaD and SvMCI groups. Loss of nocturnal dipping was significantly associated with SVaD [odds ratio (OR), 4.827; 95% confidence interval (CI), 1.07-12.05]. Conclusions It was found that SVaD is associated with loss of nocturnal BP dipping combined with increased pulse pressure and systolic BP (SBP) variability. Correction of these factors could therefore be important in the prevention of SVaD, independent of measures used to reduce BP. J Clin Neurol 2009;5:139-145Ohmine T, 2008, HYPERTENS RES, V31, P75van Boxtel MPJ, 2006, J HUM HYPERTENS, V20, P5, DOI 10.1038/sj.jhh.1001934van der Flier WM, 2005, STROKE, V36, P2116Birns J, 2005, STROKE, V36, P1308, DOI 10.1161/01.STR.0000165901.38039.5fYamamoto Y, 2005, CEREBROVASC DIS, V19, P302, DOI 10.1159/000084498BOWLER JV, 2005, J NEUROL NEUROSUR S5, V76, P35KU HM, 2004, J KOREAN NEUROPSYCHI, V43, P189O`Brien E, 2003, J HYPERTENS, V21, P821, DOI 10.1097/01.hjh.0000059016.82022.caKANG Y, 2003, INCHEON HUMAN BRAINOhkubo T, 2002, J HYPERTENS, V20, P2183de Leeuw FE, 2002, BRAIN, V125, P765O`Brien JT, 2002, ANN NY ACAD SCI, V977, P436Kario K, 2001, HYPERTENSION, V38, P852Wahlund LO, 2001, STROKE, V32, P1318Dufouil C, 2001, NEUROLOGY, V56, P921Puisieux F, 2001, EUR NEUROL, V46, P115Staessen JA, 1999, JAMA-J AM MED ASSOC, V282, P539Swan GE, 1998, NEUROLOGY, V51, P986Blacher J, 1998, HYPERTENSION, V32, P570Cummings JL, 1998, J PSYCHOSOM RES, V44, P627Kilander L, 1998, HYPERTENSION, V31, P780Guo ZC, 1997, AM J EPIDEMIOL, V145, P1106Liao DP, 1996, STROKE, V27, P2262LAUNER LJ, 1995, JAMA-J AM MED ASSOC, V274, P1846YAMAMOTO Y, 1995, STROKE, V26, P829VERDECCHIA P, 1994, HYPERTENSION, V24, P793KUUSISTO J, 1993, HYPERTENSION, V22, P771SHIMADA K, 1992, J HYPERTENS, V10, P875SCHERR PA, 1991, AM J EPIDEMIOL, V134, P1303TOHGI H, 1991, STROKE, V22, P603OBRIEN E, 1988, LANCET, V2, P397PARATI G, 1987, J HYPERTENS, V5, P93HACHINSKI VC, 1975, ARCH NEUROL-CHICAGO, V32, P632

Molecular characterization of tetracycline- and quinolone-resistant Aeromonas salmonicida isolated in Korea

The antibiotic resistance of 16 Aeromonas (A.) salmonicida strains isolated from diseased fish and environmental samples in Korea from 2006 to 2009 were investigated in this study. Tetracycline or quinolone resistance was observed in eight and 16 of the isolates, respectively, based on the measured minimal inhibitory concentrations. Among the tetracycline-resistant strains, seven of the isolates harbored tetA gene and one isolate harbored tetE gene. Additionally, quinolone-resistance determining regions (QRDRs) consisting of the gyrA and parC genes were amplified and sequenced. Among the quinolone-resistant A. salmonicida strains, 15 harbored point mutations in the gyrA codon 83 which were responsible for the corresponding amino acid substitutions of Ser83→Arg83 or Ser83→Asn83. We detected no point mutations in other QRDRs, such as gyrA codons 87 and 92, and parC codons 80 and 84. Genetic similarity was assessed via pulsed-field gel electrophoresis, and the results indicated high clonality among the Korean antibiotic-resistant strains of A. salmonicida

No Survival Benefit in Octogenarians and Nonagenarians with Extended Hemodialysis Treatment Time.

BackgroundThe population of elderly end-stage renal disease patients initiating dialysis is rapidly growing. Although longer treatment is supposed to benefit for hemodialysis (HD) patients through more solute clearance and slower fluid removal, it is not yet clear how treatment session length affects mortality risk in octogenarians and nonagenarians.MethodsIn a cohort of 112,026 incident HD patients between 2007 and 2011, we examined the association of treatment session length with all-cause mortality, adjusting for demographics and comorbid conditions. We also used restricted spline functions for age to evaluate continuous changes in the association of short (< 210 min) and extended (≥240 min) HD treatment (vs. 210 to < 240 min) with all-cause mortality over continuous age.ResultsDuring the first 91 days of dialysis, patients aged ≥80 years tended to have the lowest treatment session length (median [interquartile range] 211 [193-230] min, r > 0.5). Longer treatment was associated with better survival in patients < 65 and 65 to < 80 years but not in octogenarians/nonagenarians. The association of extended treatment (≥240 min) with better survival was attenuated across age and not significant among patients aged ≥80 years with a hazard ratio of 1.10 (95% CI 0.99-1.20). Shorter treatment sessions (< 210 min) was associated with higher mortality across all age groups.ConclusionExtended HD was not associated with lower mortality among octogenarians and nonagenarians, while it was associated with better survival among younger patients. Further studies are needed to determine the optimal treatment session length in elderly incident HD patients

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Perirenal Fluid Collection after Kidney Transplantation

A 30-year-old male presented with pitting edema. He had received a kidney transplantation 3 months previously. His serum creatinine level was increased, and a renal ultrasound showed hypoechoic fluid collection in the perirenal space and pelvic cavity. We conducted sono-guided percutaneous drainage of the fluid collected in the pelvic cavity. The chemistry of the peritoneal fluid was more equivalent to serum chemistry values than to urinary values. Simple aspiration and treatment with antibiotics were performed. We have presented a case of lymphocele after kidney transplantation. This case suggests that physicians should remember how to differentiate the pelvic cavity fluid collection in patients who have received a kidney transplant

Main Bronchial Reconstruction with Sparing of Pulmonary Parenchyma for Benign Diseases

Main bronchial reconstruction is anatomically suitable for benign main bronchial stenosis. But, it has been hardly recommended for operative mortality and morbidity. This study was aimed at providing validity and the proper clinical information of bronchoplasty for benign main bronchial stenosis by reviewing the results we obtained over the last ten years for main bronchial reconstruction operations. We retrospectively reviewed admission and office records. Twenty eight consecutive patients who underwent main bronchoplasty were included. Enrolled patients underwent main bronchial reconstruction for benign disease (tuberculosis in 21, trauma in 4, endobronchial mass in 3). Concomitant procedures with main stem bronchoplasty were performed in 19 patients. There were no incidences of postoperative mortality and significant morbidity. There were 2 cases of retained secretions, and these problems were resolved by bronchoscopy or intubation. All of the patients are still alive without obstructive airway problem. Bronchoplasty should be considered as one of the primary treatment modalities, if it is anatomically feasible

Stemness Evaluation of Mesenchymal Stem Cells from Placentas According to Developmental Stage: Comparison to Those from Adult Bone Marrow

This study was done to evaluate the stemness of human mesenchymal stem cells (hMSCs) derived from placenta according to the development stage and to compare the results to those from adult bone marrow (BM). Based on the source of hMSCs, three groups were defined: group I included term placentas, group II included first-trimester placentas, and group III included adult BM samples. The stemness was evaluated by the proliferation capacity, immunophenotypic expression, mesoderm differentiation, expression of pluripotency markers including telomerase activity. The cumulative population doubling, indicating the proliferation capacity, was significantly higher in group II (P<0.001, 31.7±5.8 vs. 15.7±6.2 with group I, 9.2±4.9 with group III). The pattern of immunophenotypic expression and mesoderm differentiation into adipocytes and osteocytes were similar in all three groups. The expression of pluripotency markers including ALP, SSEA-4, TRA-1-60, TRA-1-81, Oct-4, and telomerase were strongly positive in group II, but very faint positive in the other groups. In conclusions, hMSCs from placentas have different characteristics according to their developmental stage and express mesenchymal stemness potentials similar to those from adult human BMs

The association of asthma and its subgroups with osteoporosis: a cross-sectional study using KoGES HEXA data

Background A few studies have reported the association between asthma and osteoporosis. We aimed to analyze the association of asthma and its subgroups with osteoporosis in the Korean adult population. Methods We used the health examinee (HEXA) data from the Korean Genome and Epidemiology Study (KoGES) obtained between 2004 and 2016. We included 162,579 participants (n = 3,160 with asthma; n = 159,419 controls) who reported their previous histories of asthma and osteoporosis. The participants were categorized into 3 groups based on asthma management: participants who did not need further treatment due to controlled symptoms (well controlled); participants with ongoing treatment (being treated); participants who were not treated even though they had symptoms (not being treated). Multiple logistic regression analyses were used to calculate the adjusted odds ratios (aORs) with 95% confidence intervals (CIs) for osteoporosis. Subgroup analyses for age and sex were conducted. Results The prevalence of osteoporosis was higher in patients with asthma (13.6%) than in controls (6.8%). In the full-adjusted model, the aORs for osteoporosis were 1.74 (95% CI 1.55–1.94, P < 0.001) in patients with asthma compared to controls. There were consistent findings across the age and sex subgroups. The aORs for osteoporosis were 1.43 (95% CI 1.10–1.86, P = 0.008) in the well-controlled asthma group; 1.55 (95% CI 1.28–1.89, P < 0.001) in the being treated asthma group; and 1.96 (95% CI 1.66–2.31, P < 0.001) in the not being treated asthma group compared to the control group. Conclusion Asthma was associated with osteoporosis in the Korean adult population. Patients with asthma not being treated showed the highest ORs for osteoporosis.This research was funded by National Research Foundation (NRF) of Korea, grant number (NRF-2018-R1D1A1A0-2085328 by Hyo Geun Choi, NRF-2020R1G1A1005390 by Jee Hye Wee). The funding organization did not contribute to the design or conduct of this study, preparation, review, approval, or decision to submit this manuscript for publication