Search

Cell-free Massive MIMO (multiple-input multiple-output) is a promising distributed network architecture for 5G-and-beyond systems. It guarantees ubiquitous coverage at high spectral efficiency (SE) by leveraging signal co-processing at multiple access points (APs), aggressive spatial user multiplexing and extraordinary macro-diversity gain. In this study, we propose two distributed precoding schemes, referred to as \textit{local partial zero-forcing} (PZF) and \textit{local protective partial zero-forcing} (PPZF), that further improve the spectral efficiency by providing an adaptable trade-off between interference cancelation and boosting of the desired signal, with no additional front-hauling overhead, and implementable by APs with very few antennas. We derive closed-form expressions for the achievable SE under the assumption of independent Rayleigh fading channel, channel estimation error and pilot contamination. PZF and PPZF can substantially outperform maximum ratio transmission and zero-forcing, and their performance is comparable to that achieved by regularized zero-forcing (RZF), which is a benchmark in the downlink. Importantly, these closed-form expressions can be employed to devise optimal (long-term) power control strategies that are also suitable for RZF, whose closed-form expression for the SE is not available., This paper was accepted for publication in IEEE Transactions on Wireless Communications on March 31, 2020. {\copyright} 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses

Refeeding syndrome (RFS) is a rare, potentially life-threatening, condition seen in malnourished patients starting refeeding. RFS may provoke seizures and acute encephalopathy and can be considered an internal severe neurotrauma in need of specific treatment. The objective was to describe course of disease, treatment and, for the first time, multimodal monitoring output in a comatose patient suffering RFS. After gastric-banding and severe weight loss, the patient initiated self-starving and was transferred to our intensive care unit (ICU) following rapid refeeding. At arrival, seizures, decrease in consciousness (GCS 7) and suspected acute encephalitis was presented. Serum albumin was 8 g/l. Intracranial pressure (ICP), invasive blood pressure and electrocardiography (ECG) were monitored. Pressure reactivity (PRx) and compliance (RAP) were calculated. The patient developed congestive heart failure, anuria and general oedema despite maximal neuro- and general ICU treatment. Global cerebral oedema and hypoperfusion areas with established ischemia were seen. ECG revealed massive cardiac arrhythmia and disturbed autonomic regulation. PRx indicated intact autoregulation (−0.06 ± 0.18, mean ± SD) and relatively normal compliance (RAP = 0.23 ± 0.13). After 15 days the clinical state was improved, and the patient returned to the primary hospital. RFS was associated with serious deviations in homeostasis, high ICP levels, ECG abnormalities, kidney and lung affections. It is of utmost importance to recognize this rare syndrome and to treat appropriately. Despite the severe clinical state, cerebral autoregulation and compensatory reserve were generally normal, questioning the applicability of indirect measurements such as PRx and RAP during neuro-intensive care treatment of RFS patients with cerebral engagement.

BACKGROUND Stroke is a leading cause of disability among adults, with heavy social and economic burden worldwide. A cost-effective solution is urgently needed to facilitate identification of individual rehabilitation needs and thereby provide tailored rehabilitations to reduce disability among people with stroke. A novel digital follow-up tool Rehabkompassen® has recently been developed to facilitate capturing the multidimensional rehabilitation needs of people with stroke. OBJECTIVE To evaluate feasibility and acceptability of conducting a definitive trial to evaluate Rehabkompassen® as a digital follow-up tool among people with stroke in outpatient clinical settings. METHODS This pilot study of Rehabkompassen® is a parallel, open-label, 2-arm prospective, proof-of-concept randomized controlled trial (RCT) with allocation ratio 1:1 in a single outpatient clinic. Those who had suffered a stroke within 3 the previous months, aged >18 years, and living in the community, were included. The trial compared usual outpatient visits with Rehabkompassen® (intervention group) and without (control group) at 3-month follow-up as well as usual outpatient visit with Rehabkompassen® at 12-month follow-up. The information on recruitment rate, delivery, and uptake of the Rehabkompassen®, assessment and outcome measures completion rates, and frequency of withdrawals and loss of follow-up as well as satisfaction scores were obtained. The key outcomes were evaluated in both groups. RESULTS Twenty-eight participants (14 control, 14 Rehabkompassen®) participated in the current study, with 100 patients screened. The overall recruitment rate was 28%. Retention in the trial was 86% at 12-month follow-up, indicating high adherence to study protocol. Meanwhile, all participants used the tool as planned during their follow-ups, which provided 100% task-completion rate of using Rehabkompassen® and suggested high feasibility. Both patient- and physician-participants reported high satisfaction with the instrument, indicating high acceptability of the Rehabkompassen®. Two physicians (100%) and 18 patients (75%) were willing to use the tool in the future. Furthermore, both modified Rankin Scale (mRS) as the primary outcome and various stroke impacts as secondary outcomes were successfully collected and compared in this study. CONCLUSIONS This study demonstrated high feasibility and adherence of the study protocol as well as high acceptability of the Rehabkompassen® among patients with stroke and physicians in an outpatient setting. The information collected in this feasibility study combined with the amendments of the study protocol may improve the future definitive RCT. The results of this trial support the feasibility and acceptability of conducting a large definitive RCT. CLINICALTRIAL ClinicalTrials.gov Identifier: NCT04915027

Background Stroke is a leading cause of disability among adults, with heavy social and economic burden worldwide. A cost-effective solution is urgently needed to facilitate the identification of individual rehabilitation needs and thereby provide tailored rehabilitations to reduce disability among people who have had a stroke. A novel digital graphic follow-up tool Rehabkompassen has recently been developed to facilitate capturing the multidimensional rehabilitation needs of people who have had a stroke. Objective The aim of this study was to evaluate the feasibility and acceptability of conducting a definitive trial to evaluate Rehabkompassen as a digital follow-up tool among people who have had a stroke in outpatient clinical settings. Methods This pilot study of Rehabkompassen was a parallel, open-label, 2-arm prospective, proof-of-concept randomized controlled trial (RCT) with an allocation ratio of 1:1 in a single outpatient clinic. Patients who have had a stroke within the 3 previous months, aged ≥18 years, and living in the community were included. The trial compared usual outpatient visits with Rehabkompassen (intervention group) and without Rehabkompassen (control group) at the 3-month follow-up as well as usual outpatient visit with Rehabkompassen at the 12-month follow-up. Information on the recruitment rate, delivery, and uptake of Rehabkompassen; assessment and outcome measures completion rates; the frequency of withdrawals; the loss of follow-up; and satisfaction scores were obtained. The key outcomes were evaluated in both groups. Results In total, 28 patients (14 control, 14 Rehabkompassen) participated in this study, with 100 patients screened. The overall recruitment rate was 28% (28/100). Retention in the trial was 86% (24/28) at the 12-month follow-up. All participants used the tool as planned during their follow-ups, which provided a 100% (24/24) task completion rate of using Rehabkompassen and suggested excellent feasibility. Both patient- and physician-participants reported satisfaction with the instrument (19/24, 79% and 2/2, 100%, respectively). In all, 2 (N=2, 100%) physicians and 18 (N=24, 75%) patients were willing to use the tool in the future. Furthermore, modified Rankin Scale as the primary outcome and various stroke impacts as secondary outcomes were both successfully collected and compared in this study. Conclusions This study demonstrated the high feasibility and adherence of the study protocol as well as the high acceptability of Rehabkompassen among patients who have had a stroke and physicians in an outpatient setting in comparison to the predefined criterion. The information collected in this feasibility study combined with the amendments of the study protocol may improve the future definitive RCT. The results of this trial support the feasibility and acceptability of conducting a large definitive RCT. Trial Registration ClinicalTrials.gov NCT04915027; https://clinicaltrials.gov/ct2/show/NCT04915027

I denna artikel beskrivs ett ULF projekt i fritidshem som syftade till att utvecka verksamhet som också attraherar de äldsta eleverna, 10-12 åringarna. Utvecklingsprojektet har genomförts genom en aktionsforskningsbaserad ansats där personal i fritidshem haft återkommande reflektionsträffar tillsammans med forskare. Detta har utmynnat i att personalen har tillsammans med eleverna utvecklat olika former av aktiviteter som bygger både på elevers behov och intressen. Det har bland annat handlat om att skaffa sig mer kunskap om digitala verktyg och se över fritidshemmets inonhusmiljö för att erbjuda rum både för lugna och livliga aktiviteter.

Objectives: It is well-established that the autonomic nervous system (ANS) plays a central role in arrhythmogenesis. During and after exercise the ANS is particularly active, and since long QT syndrome (LQTS) patients have an increased risk of lethal arrhythmias during physical activity, it is important to investigate the autonomic function in these patients. In this study we investigate the ANS response during and after exercise in LQTS patients and healthy age and sex matched controls. Methods: Forty-four genotype-verified adult LQTS patients and forty-four healthy age- and sex-matched controls performed a submaximal bicycle exercise stress test. Heart rate recovery (HRR) and heart rate variability (HRV) were analyzed from registered electrocardiogram (ECG) and vector electrocardiogram (VCG) recordings collected throughout rest, exercise and in the post-exercise phase. Results: LQTS patients had a slower HRR than controls at 1- and 4-min post-exercise (p < 0.001). During the post-exercise phase, LQTS patients had a lower total power (p < 0.001), low frequency power (p < 0.001) and high frequency power (p < 0.001) than controls. In the same phase, LQTS patients off betablocker (BB) treatment showed a lower high frequency power (p = 0.01) and different low frequency/high frequency ratio (p = 0.003) when comparing with LQTS patients on BB treatment. Conclusions: The parasympathetic effect on both HRR and HRV after exercise appears depressed in this LQTS patient cohort compared to healthy controls. This indicates an aberrant ANS response during the post-exercise phase which might be compensated by BB treatment. Our findings emphasize the importance of performing further investigations to identify the role of the ANS in LQTS arrhythmogenesis. Corrigendum: Anna Lundström, Urban Wiklund, Lucy Law, Steen Jensen, Marcus Karlsson, Annika Rydberg, Corrigendum to "Aberrant autonomic pattern during the post-exercise recovery phase in Long QT syndrome patients", Autonomic Neuroscience, 2022, 102931. DOI: 10.1016/j.autneu.2021.102931

We present a method for jamming a time-division duplex link using a transceiver with a large number of antennas. By utilizing beamforming, a jammer with M antennas can degrade the spectral efficiency of the primary link more than conventional omnidirectional jammers under the same power constraint, or perform equally well with approximately 1/M of the output power. The jammer operates without any prior knowledge of channels to the legitimate transmitters, or the legitimate signals by relying on channel reciprocity. Funding Agencies|Swedish Research Council; ELLIIT

Sinus node dysfunction (SND) causes significant morbidity in patients after Fontan surgery. Heart rate variability (HRV) reflects the autonomic regulation of the heart, and changes in HRV have been associated with SND in adults. We aimed to study whether changes in HRV could be detected in 24-h electrocardiographic (ECG) recordings in Fontan patients with SND. We compared HRV results from two patient groups; patients with Fontan circulation who later required a pacemaker due to severe SND (n = 12) and patients with Fontan circulation and SND, without indication for pacemaker treatment (n = 11), with two control groups; patients with Fontan circulation without SND (n = 90) and healthy controls (n = 66). The Poincaré plot index SD2 (representing changes in heart rate over 24-h) and the very low-frequency (VLF) HRV component were significantly higher in both SND groups, both compared with healthy controls and patients with Fontan circulation without SND. In SND patients with pacemakers, SD2 and VLF were slightly reduced compared to SND patients without pacemaker (p = 0.06). In conclusion, in Fontan patients with SND the HRV is significantly higher compared to healthy controls and Fontan patients without SND. However, in patients with severe SND requiring pacemaker, SD2 and VLF tended to be lower than in patients with SND without pacemaker, which could indicate a reduced diurnal HRV in addition to the severe bradycardia. This is a small study, but our results indicate that HRV analysis might be a useful method in the follow-up of Fontan patients regarding development of SND. Electronic supplementary material The online version of this article (10.1007/s00246-019-02092-5) contains supplementary material, which is available to authorized users.

We consider transmission of system information in a cell-free massive MIMO system, when the transmitting access points do not have any channel state information and the receiving terminal has to estimate the channel based on downlink pilots. We analyze the system performance in terms of outage rate and coverage probability, and use space-time block codes to increase performance. We propose a heuristic method for pilot/data power optimization that can be applied without any channel state information at the access points. We also analyze the problem of grouping the access points, which is needed when the single-antenna access points jointly transmit a space-time block code., Comment: Published in IEEE Transactions on Communications, 30 pages, 10 figures

Cell-free Massive multiple-input multiple-output (MIMO) ensures ubiquitous communication at high spectral efficiency (SE) thanks to increased macro-diversity as compared cellular communications. However, system scalability and performance are limited by fronthauling traffic and interference. Unlike conventional precoding schemes that only suppress intra-cell interference, full-pilot zero-forcing (fpZF), introduced in [1], actively suppresses also inter-cell interference, without sharing channel state information (CSI) among the access points (APs). In this study, we derive a new closed-form expression for the downlink (DL) SE of a cell-free Massive MIMO system with multi-antenna APs and fpZF precoding, under imperfect CSI and pilot contamination. The analysis also includes max-min fairness DL power optimization. Numerical results show that fpZF significantly outperforms maximum ratio transmission scheme, without increasing the fronthauling overhead, as long as the system is sufficiently distributed., Paper published in 2018 IEEE Global Conference on Signal and Information Processing (GlobalSIP). {\copyright} 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses

Massive MIMO (Multiple-Input--Multiple-Output) is a cellular-network technology in which the base station is equipped with a large number of antennas and aims to serve several different users simul ...

The main purpose of this study was to investigate relationships between self-report measures such as mood state, emotional recovery, and perceived exertion for a runner during a continental run. Se ...

The use of diffuse, highly reflective optical components, in particular, a hemispherical BaSO4 diffuser, at the point of light injection into non-transparent or turbid media was evaluated as a means to increase the measurement sensitivity of spectroscopic absorption measurements. By performing the light injection from, e.g., an optical fiber through a component designed to make the light diffuse and to reflect (and thereby re-inject) light scattered from the sample, the total amount of light delivered into the sample is increased. Further, the occurrence of possible interference fringes is strongly reduced.

This experimental study investigated differences in perceived restorativeness, mood, attention capacity and physiological reactions when visiting city and forest environments. Twenty female patient ...

Objectives: To report and evaluate a complex touch massage intervention according to the British Medical Research Council framework. This study aimed to evaluate the effects of touch massage on lev ...

Aims To evaluate the role of the autonomic nervous system (ANS) in the development of insulin resistance (IR) and assess the relationship between IR and activity of ANS using power spectrum analysis of heart rate variability (HRV). Subjects and methods Twenty-three healthy first-degree relatives of patients with type 2 diabetes (R) and 24 control subjects without family history of diabetes (C) group-matched for age, BMI and sex were included. Insulin sensitivity (M value) was assessed by hyperinsulinemic (56 mU/m2/min) euglycemic clamp. Activity of the ANS was assessed using power spectrum analysis of HRV in long-term recordings, i.e., 24-h ECG monitoring, and in short-term recordings during manoeuvres activating the ANS. Computed tomography was performed to estimate the amount and distribution of abdominal adipose tissue. Results Insulin sensitivity (M value, mg/kg lbm/min) did not differ significantly between the R and C groups. Total spectral power (Ptot) and very low-frequency (PVLF) power was lower in R than C during 24 h ECG-recordings (p = 0.02 and p = 0.03). The best fit multiple variable linear regression model (r2 = 0.37, p

An intelligent rollator (IRO) was developed that aims at obstacle detection and guidance to avoid collisions and accidental falls. The IRO is a retrofit four-wheeled rollator with an embedded computer, two solenoid brakes, rotation sensors on the wheels and IR-distance sensors. The value reported by each distance sensor was compared in the computer to a nominal distance. Deviations indicated a present obstacle and caused activation of one of the brakes in order to influence the direction of motion to avoid the obstacle. The IRO was tested by seven healthy subjects with simulated restricted and blurred sight and five stroke subjects on a standardised indoor track with obstacles. All tested subjects walked faster with intelligence deactivated. Three out of five stroke patients experienced more detected obstacles with intelligence activated. This suggests enhanced safety during walking with IRO. Further studies are required to explore the full value of the IRO.

Aim: To measure the effect of sound and whole-body vibration on infants' heart rate and heart rate variability during ground and air ambulance transport.Methods: Sixteen infants were transported by ...

The technique in Fontan surgery has developed from the lateral tunnel (LT) toward the extracardiac conduit (EC) used to reduce long-term complications such as atrial arrhythmia and sinus node dysfunction. Heart rate variability (HRV) examines cardiac nervous activity controlling the sinus node. This study aimed to investigate HRV in a cohort of children with univentricular hearts, focusing on the relation between HRV and surgical procedure. For 112 children with Fontan circulation, HRV was analyzed using power spectral analysis. Spectral power was determined in three regions: very-low-frequency (VLF), low-frequency (LF), and high-frequency (HF) regions. Patients were compared with 66 healthy controls subject. Patients with LT were compared with patients who had EC. The children with Fontan circulation showed a significantly reduced HRV including total power (P < 0.0001), VLF (P < 0.0001), LF (P < 0.0001), and HF (P = 0.001) compared with the control subjects. The LT and EC patients did not differ significantly. Reduced HRV was found in both the LT and EC patients. In terms of HRV reduction, EC was not superior to LT.

The pathophysiology of the hemodynamic responses to postural stress in familial amyloidotic polyneuropathy (FAP) remains to be elucidated. The aim of the study was to evaluate hemodynamic responses after tilt reversal in FAP. Systolic blood pressure (BP) and heart rate variability (HRV) were analyzed in the baseline, 70° upright position, and after tilt reversal in 15 FAP patients and 14 healthy controls. Beat-to-beat BP was recorded with a Finapres device. Maximum systolic BP after tilt reversal was increased with 22 ± 13 mm Hg in FAP patients as compared with baseline (BP overshoot), whereas controls showed a significantly lower BP overshoot (8 ± 6 mm Hg, P0.001). In all states, total spectral power and the power of the low and high frequency components were all significantly lower than those of the controls (P0.01). In a linear regression analysis adjusted for age, we found a significant inverse relation between BP overshoot and HRV (total spectral power, power of the low-frequency and high-frequency components) in all three states (standardized β between -0.74 to -0.53, P0.01). Five FAP patients presented a trial arrhythmia precluding HRV analysis: four of those presented BP overshoots ≥ 12 mm Hg. BP overshoot may be a marker to assess the progression of cardiac autonomic dysfunction, especially as heart arrhythmia in many FAP patients prevent HRV analysis. In addition, assessment of the post-tilt BP reaction points to possible treatment modalities for orthostatic hypotension at least in the early stages of the disease.

Media have anecdotally reported that drinking energy drinks in combination with alcohol and exercise could cause sudden cardiac death. This study investigated changes in the electrocardiogram (ECG) and heart rate variability after intake of an energy drink, taken in combination with alcohol and exercise.Ten healthy volunteers (five men and five women aged 19-30) performed maximal bicycle ergometer exercise for 30 min after: (i) intake of 0.75 l of an energy drink mixed with alcohol; (ii) intake of energy drink; and, (iii) no intake of any drink. ECG was continuously recorded for analysis of heart rate variability and heart rate recovery.No subject developed any clinically significant arrhythmias. Post-exercise recovery in heart rate and heart rate variability was slower after the subjects consumed energy drink and alcohol before exercise, than after exercise alone.The healthy subjects developed blunted cardiac autonomic modulation after exercising when they had consumed energy drinks mixed with alcohol. Although they did not develop any significant arrhythmia, individuals predisposed to arrhythmia by congenital or other rhythm disorders could have an increased risk for malignant cardiac arrhythmia in similar situations.

—An analysis of broadcasting in massive MIMO (multiple-input and multiple-output) systems with a limited coherence interval is presented. When broadcasting common information, such as control signals, the base station does not have channel state information to the terminals. We propose that the base station broadcasts this common information using a low dimensional orthogonal space-time block code (OSTBC). This code is mapped onto the large antenna array with the use of a dimension reducing matrix, effectively “shrinking” the channel. The terminal can estimate the effective channel and decode the information, even when the coherence interval is short compared to the number of base station antennas. Different OSTBCs are compared in terms of outage capacity in practical scenarios using estimated CSI. In particular, the trade-off between diversity and rate, when little or no time/frequency diversity is available, is investigated.

The aim of the study was to evaluate hemodynamic responses after tilt reversal in familial amyloid polyneuropathy (FAP). Systolic blood pressure (BP) and heart rate variability (HRV) were analyzed ...

—A scheme for a multi-antenna jammer, jamming a SISO primary link working in TDD mode is presented. The jammer relies on reciprocity to estimate the channel to a terminal in the primary link blindly. The jammer can then beamform noise towards this user to degrade the performance of the primary link. Simulations show that, for certain scenarios, the proposed jammer can do the same damage to the primary link as an omnidirectional jammer, but with close to two orders of magnitude lower output power.

Our aim was to evaluate the intermittent use of a handheld ECG system for detecting silent arrhythmias and cardiac autonomic dysfunction in children with univentricular hearts.Twenty-seven patients performed intermittent ECG recordings with handheld devices during a 14-day period. A manual arrhythmia analysis was performed. We analyzed heart rate variability (HRV) using scatter plots of all interbeat intervals (Poincaré plots) from the total observation period. Reference values of HRV indices were determined from Holter-ECGs in 41 healthy children.One asymptomatic patient had frequent ventricular extra systoles. Another patient had episodes with supraventricular tachycardia (with concomitant palpitations). Seven patients showed reduced HRV.Asymptomatic arrhythmia was detected in one patient. The proposed method for pooling of intermittent recordings from handheld or similar devices may be used for detection of arrhythmias as well as for cardiac autonomic dysfunction.

Det anses vara en självklarhet att omvårdnaden ska bedrivas utifrån evidens. Trots detta föreligger det brister i sjuksköterskors användning av evidens i omvårdnaden vilket gör att patienter får vård som hade kunnat undvikas eller till och med får vård som kan vara skadlig. Syftet var att beskriva vad som påverkar sjuksköterskans användning av evidensbaserad omvårdnad. En litteraturstudie gjordes utifrån 19 vetenskapliga artiklar. Analysen utmynnade i fyra kategorier: hinder, kunskapskällor, användning och attityd. Resultatet visade att tidsbrist är ett hinder för sjuksköterskors användning av forskningsresultat. Avdelningen och organisationens attityd påverkar sjuksköterskors användning av forskningsresultat i omvårdnaden. Sjuksköterskor upplever svårigheter med att omsätta forskningsresultat i verksamheten vilket kan relateras till bristande kunskap och färdighet. Studien visade att sjuksköterskor hämtar kunskap från riktlinjer, utbildningar och kollegor. Utbildningen påverkar forskningsanvändningen hos sjuksköterskor då de med en högre utbildningsnivå använder sig av forskningsresultat i större utsträckning. Organisationen bör lägga resurser på utbildning och satsa på att anställa fler specialistsjuksköterskor. Ytterligare forskning behövs för att ta reda på om sjuksköterskor använder sig av patienters erfarenheter som en del i omvårdnadsbeslut som tas samt studera om samband föreligger mellan tidsbrist och okunskap relaterat till forskningsanvändning.

We propose an optical method for non-invasive characterisation of wood samples based on two optical techniques: time-resolved diffuse optical spectroscopy and gas in scattering media absorption spectroscopy. While the latter is sensitive to gases present inside wood pores, the former extracts information on the bulk material regarding light scattering and absorption. Measurements on spruce samples, cut along different wood fibre directions, are presented to show an example of the advantages of this combined approach: by applying these two non-destructive techniques together, in fact, relevant information on wood such as porosity, permeability and moisture content can be assessed. Furthermore, the chemical composition, internal structure and the anisotropy due to the wood fibres can be investigated.