Initial Access Research Articles

Functional status, pre-dialysis health and clinical outcomes among elderly dialysis patients

BackgroundElderly patients comprise the fastest growing population initiating dialysis in United States. The impact of poor functional status and pre-dialysis health status on clinical outcomes in elderly dialysis patients is not well studied.MethodsWe studied a retrospective cohort of 49,645 incident end stage renal disease patients that initiated dialysis between January 1, 2008 and December 31, 2008 from the United States Renal Data System with linked Medicare data covering at least 2 years prior to dialysis initiation. Using logistic regression models adjusted for pre-dialysis health status and other cofounders, we examined the impact of poor functional status as defined from form 2728 on 1-year all-cause mortality as primary outcome, type of dialysis modality (hemodialysis vs. peritoneal dialysis), and type of initial vascular access (arteriovenous access vs. central venous catheter) among hemodialysis patients as secondary outcomes.ResultsMean age was 72 ± 11 years. At dialysis initiation, 18.7% reported poor functional status, 88.9% had at least 1 pre-dialysis hospitalization, and 27.8% did not receive pre-dialysis nephrology care. In adjusted analyses, 1-year mortality was higher in patients with poor functional status (OR, 1.48; 95% CI, 1.40–1.57). Adjusted odds of being initiated on hemodialysis than peritoneal dialysis (odds ratio [OR], 1.39; 95% confidence interval [CI], 1.16–1.66) were higher in patients with poor functional status. Poor functional status decreased the adjusted odds of starting hemodialysis with arteriovenous access as compared to central venous catheter (OR, 0.79; 95% CI, 0.72–0.86).ConclusionPoor functional status in elderly patients with end stage renal disease is associated with higher odds of initiating hemodialysis; increases the risk of central venous catheter use, and is an independent predictor of 1-year mortality.

ICT access: Testing for convergence across countries

ABSTRACTOur objectives for this article are twofold: first, to examine the convergence of nations with regard to ICT access; and second, to see whether countries in the same continental region (South and East Asia, West and Middle East Asia, Africa, Eastern Europe, Western Europe, North America, South America, and Oceania) or having same initial ICT access have coalesced into groups. We constructed an ICT access index using three indicators (mobile phone, Internet, and broadband use per 100 population) for a sample of 198 nations for the 16-year period from 2000 to 2015. Results show that digital divide has declined in relative terms, but not in absolute terms. The countries, starting at lower ICT levels, are not adopting ICT faster than the leaders. Continental region-wise analysis also shows that the catch-up is maximum for already developed countries, and minimum for countries in African and Oceania continental regions.

Residential Area Life Expectancy: Association With Outcomes and Processes of Care for Patients With ESRD in the United States

The effects of underlying noncodified risks are unclear on the prognosis of patientswith end-stage renal disease (ESRD). Weaimed to evaluate the association of residential area life expectancy with outcomes and processes of care for patients with ESRD in the United States. Retrospective cohort study. Adult patients with incident ESRD between 2006 and 2013 recorded in the US Renal Data System (n=606,046). The primary exposure was life expectancy in the patient's residential county estimated by the Institute for Health Metrics and Evaluation. Death, placement on the kidney transplant wait list, living and deceased donor kidney transplantation, and posttransplantation graft loss. Median life expectancies of patients' residences were 75.6 (males) and 80.4 years (females). Compared to the highest life expectancy quintile and adjusted for demographic factors,disease cause, and multiple comorbid conditions, the lowest quintile had adjusted HRs for mortality of 1.20 (95% CI, 1.18-1.22); placement onto the waiting list, 0.68 (95% CI, 0.67-0.70); living donor transplantation, 0.53 (95% CI, 0.51-0.56); posttransplantation graft loss, 1.35 (95% CI, 1.27-1.43); and posttransplantation mortality, 1.29 (95% CI, 1.19-1.39). Patients living in areas with lower life expectancy were less likely to be informed about transplantation, be under the care of a nephrologist, or receive an arteriovenous fistula as the initial dialysis access. Results remained consistent with additional adjustment for zip code-level median income, population size, and urban-rural locality. Potential residual confounding and attribution of effects to individuals based on residential area-level data. Residential area life expectancy, a proxy for socioeconomic, environmental, genetic, and behavioral factors, was independently associated with mortality and process-of-care measures for patients with ESRD. These results emphasize the underlying effect on health outcomes of the environment in which patients live, independent of patient-level factors. These findings may have implications for provider assessments.

Initial Access, Mobility, and User-Centric Multi-Beam Operation in 5G New Radio

5G radio access networks are expected to provide very high capacity, ultra-reliability and low latency, seamless mobility, and ubiquitous end-user experience anywhere and anytime. Driven by such stringent service requirements coupled with the expected dense deployments and diverse use case scenarios, the architecture of 5G New Radio (NR) wireless access has further evolved from the traditionally cell-centric radio access to a more flexible beam-based user-centric radio access. This article provides an overview of the NR system multi-beam operation in terms of initial access procedures and mechanisms associated with synchronization, system information, and random access. We further discuss inter-cell mobility handling in NR and its reliance on new downlink-based measurements to compensate for a lack of always-on reference signals in NR. Furthermore, we describe some of the user-centric coordinated transmission mechanisms envisioned in NR in order to realize seamless intra/inter-cell handover between physical transmission and reception points and reduce the interference levels across the network.

Abstract No. 623 Technique of maintaining portal venous access and obtaining a more central portal vein puncture when the initial peripheral access may be prone to technical difficulties and potential serious complications

Abstract No. 623 Technique of maintaining portal venous access and obtaining a more central portal vein puncture when the initial peripheral access may be prone to technical difficulties and potential serious complications

High-Speed Train Communications Standardization in 3GPP 5G NR

In 3GPP New Radio (NR), high-speed train (HST) is considered as one of the essential verticals in 5G applications. In this article, architectures and applications of 5G network slicing to HST are described. In addition, both higher layer and physical layer technologies are proposed to improve the quality of train communication in a 5G system. End-to-end network slicing that penetrates both the core network and radio access network can meet various performance requirements for 5G HST use cases, thanks to the flexibility offered by the proposed technologies. The higher layer technologies proposed in this article cover initial access, mobility management, and linear cell designs. Following the descriptions of evaluation parameters for the HST scenario adopted in 3GPP, the proposed physical layer technologies for HST applications including numerology and reference signal designs are explained. Link-level evaluation results are shown to demonstrate the superior performance of the proposed methods.

Clinical Trial End Points for Hemodialysis Vascular Access: Background, Rationale, and Definitions.

Hemodialysis vascular access is the “lifeline” for patients on hemodialysis. Unfortunately, because of its poor patency and significant complication rate, it is also the “Achilles heel” of hemodialysis. For example, the current unassisted arteriovenous fistula (AVF) maturation rate is only

Cosmetic outcomes of infraumbilical, supraumbilical, and transumbilical entry routes in laparoscopic surgery.

The aim of the present study was to determine which of the umbilical entry routes for intraperitoneal access has a better cosmetic result. This was a prospective study (Canadian Task Force classification II-1). In total, 105 patients who underwent laparoscopic surgery were included. A vertical or transverse umbilical incision is appropriately made for the trocar to be inserted, and an infraumbilical, supraumbilical, or transumbilical route was preferred for initial intraperitoneal access. Demographic data of patients, body mass indices, entry point of the trocars (infraumbilical-transumbilical-supraumbilical), type of incision (vertical-transverse), duration of the operation, and scar properties at postoperative week 12 were prospectively collected and analyzed. The Vancouver scar scale was used to evaluate the cosmetic results. Cosmetic results did not differ statistically between the transumbilical-infraumbilical-supraumbilical groups. The variables, such as vascularity, height, and total score, of the Vancouver scar scale were significantly higher in patients who had transverse incisions. There was no statistically significant effect of using a Veress needle with the cosmetic results. There was no statistically significant correlation between age, gravida, body mass indices, skin thickness, time of entry, duration of the operation, and cosmetic results in terms of vascularity, height, and total score. During laparoscopic surgery, each patient should be assessed individually for the satisfaction of the patient and, thereby, of the surgeon in terms of cosmetic outcomes. Vertical incision offers superior cosmetic effects than transverse incision. Further research is required to define long-term scar-related outcomes of the laparoscopic intraperitoneal access techniques.

Is speech recognition automatic? Lexical competition, but not initial lexical access, requires cognitive resources

Abstract Current models of spoken word recognition suggest that multiple lexical candidates are activated in parallel upon hearing an utterance, with these lexical hypotheses competing with each other for recognition. The current project investigated the effect of cognitive load on initial lexical access and later lexical competition. In a set of priming studies, the lexicality of the primes (i.e., non-word vs. word) was manipulated to dissociate these two sub-processes. We tested performance on a semantic association task under conditions with no additional load, or with cognitive load that used cognitive resources that are either general or more specific to phonological processing. The results suggest that the initial access of lexical items is relatively automatic. In contrast, maintaining lexical candidates in competition requires cognitive resources, and these resources are specific to phonological processing. The overall result pattern provides insights into differences in the way that lexical activation and competition operate.

Does letter rotation slow down orthographic processing in word recognition?

Leading neural models of visual word recognition assume that letter rotation slows down the conversion of the visual input to a stable orthographic representation (e.g., local detectors combination model; Dehaene, Cohen, Sigman, & Vinckier, 2005, Trends in Cognitive Sciences, 9, 335-341). If this premise is true, briefly presented rotated primes should be less effective at activating word representations than those primes with upright letters. To test this question, we conducted a masked priming lexical decision experiment with vertically presented words either rotated 90° or in marquee format (i.e., vertically but with upright letters). We examined the impact of the format on both letter identity (masked identity priming: identity vs. unrelated) and letter position (masked transposed-letter priming: transposed-letter prime vs. replacement-letter prime). Results revealed sizeable masked identity and transposed-letter priming effects that were similar in magnitude for rotated and marquee words. Therefore, the reading cost from letter rotation does not arise in the initial access to orthographic/lexical representations.

Atypical chemokine receptor 4 shapes activated B cell fate.

Activated B cells can initially differentiate into three functionally distinct fates-early plasmablasts (PBs), germinal center (GC) B cells, or early memory B cells-by mechanisms that remain poorly understood. Here, we identify atypical chemokine receptor 4 (ACKR4), a decoy receptor that binds and degrades CCR7 ligands CCL19/CCL21, as a regulator of early activated B cell differentiation. By restricting initial access to splenic interfollicular zones (IFZs), ACKR4 limits the early proliferation of activated B cells, reducing the numbers available for subsequent differentiation. Consequently, ACKR4 deficiency enhanced early PB and GC B cell responses in a CCL19/CCL21-dependent and B cell-intrinsic manner. Conversely, aberrant localization of ACKR4-deficient activated B cells to the IFZ was associated with their preferential commitment to the early PB linage. Our results reveal a regulatory mechanism of B cell trafficking via an atypical chemokine receptor that shapes activated B cell fate.

Genetic Algorithm‐Based Beam Refinement for Initial Access in Millimeter Wave Mobile Networks

Initial access (IA) is identified as a key challenge for the upcoming 5G mobile communication system operating at high carrier frequencies, and several techniques are currently being proposed. In this paper, we extend our previously proposed efficient genetic algorithm‐ (GA‐) based beam refinement scheme to include beamforming at both the transmitter and the receiver and compare the performance with alternative approaches in the millimeter wave multiuser multiple‐input‐multiple‐output (MU‐MIMO) networks. Taking the millimeter wave communications characteristics and various metrics into account, we investigate the effect of different parameters such as the number of transmit antennas/users/per‐user receive antennas, beamforming resolutions, and hardware impairments on the system performance employing different beam refinement algorithms. As shown, our proposed GA‐based approach performs well in delay‐constrained networks with multiantenna users. Compared to the considered state‐of‐the‐art schemes, our method reaches the highest service outage‐constrained end‐to‐end throughput with considerably less implementation complexity. Moreover, taking the users’ mobility into account, our GA‐based approach can remarkably reduce the beam refinement delay at low/moderate speeds when the spatial correlation is taken into account. Finally, we compare the cases of collaborative users and noncollaborative users and evaluate their difference in system performance.

Mortality of diabetic on chronic dialysis in Tunisia.

Survival rates of diabetic patients on maintenance hemodialysis (HD) are reported to be poorer in Tunisia than in developed countries. This study aims to specify the epidemio-logical, clinical, and biological characteristics of diabetic disease, chronic kidney disease (CKD), and comorbidities at the initiation of HD and investigate factors associated with mortality during the dialysis period. We retrospectively analyzed the outcome of diabetic patients who were initiated on HD from 2007 to 2012 at the Rabta Hospital of Tunis. During the follow-up period, all morbid events and deaths were recorded. Univariate analysis and multivariate analysis were performed to identify risk factors associated with mortality in our population. The study population included 142 patients. The mean age was 58.7 ± 11.9 years. The sex ratio male/female was 1.4. One hundred and twenty-seven patients were type 2 diabetics (89.4%). Diabetic nephropathy was the main initial nephropathy (87.3%). CKD was diagnosed at Stages 4 or 5 in 95.1% of cases. HD was started in emergency conditions in 68.6% of cases. The one-year and the five-year survival rates were 42% and 17%, respectively. At initiation of HD, low socioeconomic status (P = 0.001), advanced age (P = 0.008), low body mass index (P = 0.04), history of stroke (P = 0.04), peripheral neuropathy (P = 0.02), initial vascular access (P = 0.03), secondary hyperpara-thyroidism (P = 0.03), nephrotic-range proteinuria (P = 0.01), and glycated hemoglobin ≤7% (P = 0.03) were associated with higher mortality rate. During dialysis period, cardiovascular events (P = 0.02), infectious complications (P = 0.04), and secondary hyperparathyroidism (P = 0.04) were significantly more noticeable among deceased patients. Due to poor survival rates of diabetic patients on HD, prevention, early detection, and management of diabetic CKD patients should be the way to go forward.

Vascular access in lipoprotein apheresis: a retrospective analysis from the UK's largest lipoprotein apheresis centre.

Lipoprotein apheresis (LA) has proven to be an effective, safe and life-saving therapy. Vascular access is needed to facilitate this treatment but has recognised complications. Despite consistency in treatment indication and duration there are no guidelines in place. The aim of this study is to characterise vascular access practice at the UK's largest LA centre and forward suggestions for future approaches. A retrospective analysis of vascular access strategies was undertaken in all patients who received LA treatment in the low-density lipoprotein (LDL) Apheresis Unit at Harefield Hospital (Middlesex, UK) from November 2000 to March 2016. Fifty-three former and current patients underwent 4260 LA treatments. Peripheral vein cannulation represented 79% of initial vascular access strategies with arteriovenous (AV) fistula use accounting for 15%. Last used method of vascular access was peripheral vein cannulation in 57% versus AV fistula in 32%. Total AV fistula failure rate was 37%. Peripheral vein cannulation remains the most common method to facilitate LA. Practice trends indicate a move towards AV fistula creation; the favoured approach receiving support from the expert body in this area. AV fistula failure rate is high and of great concern, therefore we suggest the implementation of upper limb ultrasound vascular mapping in all patients who meet treatment eligibility criteria. We encourage close ties between apheresis units and specialist surgical centres to facilitate patient counselling and monitoring. Further prospective data regarding fistula failure is needed in this expanding treatment field.

LTE/Wi-Fi/mmWave RAN-Level Interworking Using 2C/U Plane Splitting for Future 5G Networks

Integration of the promising millimeter wave (mmWave) technology into the legacy cellular network is one of the main challenges toward a unified 5G cellular network. However, directly controlling the access of mmWave small cells (SCs) via the LTE eNB using the conventional LTE/WLANs interworking seems to be an inefficient solution. This is due to the short transmission range of the mmWave signal accompanied with the inevitable use of directional communications in these bands. In this paper, a novel radio access network-level hierarchical multi-band heterogeneous network (HetNet) is proposed to efficiently overlay mmWave SCs over LTE. In this architecture, the Wi-Fi medium coverage band is used as an intermediate level between the large coverage LTE band and the small coverage mmWave band. The Wi-Fi band via the proposed concept of Wi-Fi/mmWave sub-clouds enables precise control to the access over the mmWave band. Whereas, the LTE eNB only controls the access over the distributed Wi-Fi/mmWave subclouds. Accordingly, a novel concept of two-level control and user data (2C/U) planes splitting is introduced in this paper. In this 2C/U plane splitting, the LTE eNB controls the network access over the distributed sub-clouds using the first level of control (C1-plane). The second level of control (C2-plane), provided by the Wi-Fi band, controls the access over the distributed mmWave SCs inside the sub-clouds. Thanks to this distributed control, the mmWave band can be efficiently utilized and the complexity of the mmWave initial access can be highly reduced. Moreover, the associated signaling/processing load on both LTE eNB and core network can be highly relaxed. Analytical and numerical analysis assure the performance superiority of the proposed LTE/Wi-Fi/mmWave HetNet over the conventional LTE/mmWave HetNet.

An Efficient Contention Resolution Scheme for Massive IoT Devices in Random Access to LTE-A Networks

Long-Term Evolution-Advanced (LTE-A) networks have been regarded as having great potential to support the Internet of Things (IoT). However, the high probability of preamble collisions when massive numbers of IoT devices try to access the network within a short period has become a significant problem. In this paper, we propose a new scheme to efficiently handle the initial access contention for massive numbers of IoT devices in LTE-A networks. The proposed scheme divides an entire preamble set into $k$ subgroups; then, contention resolution is performed in each subgroup independently in a parallel and pipelined manner. Simulation results show that our scheme leads to considerable improvement in terms of average access delay and standard deviation of access delays without increasing blocking probability. Moreover, utilization of preamble resources is greatly improved by reducing the number of random access slots, where only a few devices participate in preamble selection.

Stroke identification by criteria based dispatch - a register based study.

BackgroundRapid and precise dispatch of resources is a key element in pre‐hospital emergency medicine. Emergency medical communication centres (EMCCs) dispatch resources based on protocols and guidelines, balancing the acute need of the individual and the resource allocation of the pre‐hospital emergency medical system. The aim of this study was to determine the validity of stroke identification by the Norwegian dispatch guidelines.Method and materialThis was a register‐based study where patients suspected for stroke were compared to those with the final diagnosis of stroke as an indicator group for the guideline validation. One EMCC and its three associated hospitals participated with 13 months of data. Four subcodes of the stroke dispatch code were defined as suspicious of stroke and further analysed. Factors associated with stroke identification were explored.ResultsThe sensitivity for identifying a stroke patient at initial EMCC contact was 57.9% (51.5, 64.1), specificity was 99.1% (98.9, 99.2), positive predictive value was 45.7% (40.1, 51.4) and negative predictive value was 99.4% (99.3, 99.5). The emergency medical access telephone (113) was initial EMCC contact line in only 48% of the cases. Paralyses and admittance to a smaller hospital were associated with increased probability for stroke (OR 2.6, P = 0.001 and OR 2.7, P = 0.01), respectively.ConclusionThe sensitivity for identification of stroke patients by the dispatch guidelines is modest, while the specificity is high. The 113 telephone line was initial EMCC access point for less than half of the stroke patients.

Outcomes of Simultaneous Peritoneal Dialysis and Arteriovenous Fistula Placement in End-Stage Renal Disease Patients.

Peritoneal dialysis (PD) interruption requiring hemodialysis (HD) is not uncommon and its frequently abrupt nature prevents timely creation of permanent HD access and avoidance of central venous catheters (CVC). We retrospectively studied a cohort of 24 end-stage renal disease (ESRD) patients (mean age 50.7 years, 83.3% African-Americans, 58.3% females, time on dialysis interquartile range [IQR] 0 - 65 days) who had simultaneous PD catheter insertion and backup arteriovenous fistula (AVF) creation between January 1, 2012, and December 31, 2013. The primary outcome of interest was the percent of patients receiving HD through the backup AVF at the time of PD interruption. A median (IQR) for PD catheter use after its insertion was 10.5 (2 - 20) days. After the mean follow-up of 19.6 months, 12 patients remained on PD, 2 patients received a kidney transplant, and 1 patient died. The overall AVF patency was 66.7%. A total of 9 (37.5%) patients had PD interruption requiring permanent (8 patients) or temporary (1 patient) HD after the mean (standard deviation [SD]) follow-up of 12.3 (8.2) months. Arteriovenous fistula was used as the initial access in 4 patients, and in 3 patients the original AVF was used after additional surgical revision. Forty-four percent of patients with a backup AVF fistula avoided CVC at the time of PD interruption requiring HD. The simultaneous AVF creation at the time of PD catheter insertion reduced but did not fully eliminate CVC at the time of PD interruption. Larger studies are needed to evaluate the utility of a backup AVF in PD patients.

Design and Analysis of Initial Access in Millimeter Wave Cellular Networks

Initial access is the process which allows a mobile user to first connect to a cellular network. It consists of two main steps: cell search (CS) on the downlink and random access (RA) on the uplink. Millimeter wave (mmWave) cellular systems typically must rely on directional beamforming (BF) in order to create a viable connection. The beamforming direction must therefore be learned-as well as used-in the initial access process for mmWave cellular networks. This paper considers four simple but representative initial access protocols that use various combinations of directional beamforming and omnidirectional transmission and reception at the mobile and the BS, during the CS and RA phases. We provide a system-level analysis of the success probability for CS and RA for each one, as well as of the initial access delay and user-perceived downlink throughput (UPT). For a baseline exhaustive search protocol, we find the optimal BS beamwidth and observe that in terms of initial access delay it is decreasing as blockage becomes more severe, but is relatively constant (about $\pi/12$) for UPT. Of the considered protocols, the best trade-off between initial access delay and UPT is achieved under a fast cell search protocol.

Young Men’s Experiences of Accessing and Receiving Help From Child and Adolescent Mental Health Services Following Self-Harm

Given the high rates of completed suicide and poor help-seeking among young men, this research explored how young men, who had successfully sought help from a Child and Adolescent Mental Health Service (CAMHS), experienced help-seeking. The study focused on the factors that facilitated initial access and ongoing engagement in services. Eight young men between the ages of 16 to 18, who had entered CAMHS following self-harm or suicidal ideation, and who were engaged in ongoing therapy, were recruited. Each young man was interviewed to elicit his personal experiences of help-seeking and help-receiving. Interviews were transcribed and subjected to Interpretative Phenomenological Analysis. Four superordinate themes, which overarched participant’s individual experiences, emerged from the data: Role of external adult in recognizing, normalizing, and initiating help-seeking; challenging and renegotiating perception of need for help and meaning behind this need; maintaining an independent self; and mechanisms of engagement. Help-seeking was described as a journey of two stages: (a) initial access and (b) ongoing engagement, during which the presence and timing of external influences (parents, teachers) and internal influences (personal beliefs and attitudes) were crucial. A model of help-seeking in young men who self-harmed was developed, which considered both access and engagement to help, and combined a consideration of internal and external influences on their ability to access help.