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Massive multiple-input multiple-output (M-MIMO) is a substantial pillar in fifth generation (5G) mobile communication systems. Although the maximum likelihood (ML) detector attains the optimum performance, it has an exponential complexity. Linear detectors are one of the substitutions and they are comparatively simple to implement. Unfortunately, they sustain a considerable performance loss in high loaded systems. They also include a matrix inversion which is not hardware-friendly. In addition, if the channel matrix is singular or nearly singular, the system will be classified as an ill-conditioned and hence, the signal cannot be equalized. To defeat the inherent noise enhancement, iterative matrix inversion methods are used in the detectors’ design where approximate matrix inversion is replacing the exact computation. In this paper, we study a linear detector based on iterative matrix inversion methods in realistic radio channels called QUAsi Deterministic RadIo channel GenerAtor (QuaDRiGa) package. Numerical results illustrate that the conjugate-gradient (CG) method is numerically robust and obtains the best performance with lowest number of multiplications. In the QuaDRiGA environment, iterative methods crave large n to obtain a pleasurable performance. This paper also shows that when the ratio between the user antennas and base station (BS) antennas ( β ) is close to 1, iterative matrix inversion methods are not attaining a good detector’s performance.

Lumbrical muscles originate on the flexor digitorum profundus (FDP) tendons and, during fist making, they move in the same direction when FDP muscle produces maximal proximal tendon gliding. Injuries of the bipennate lumbricals have been described when a shear force acts between the origins on adjacent tendons of the FDP, as they glide in opposite directions in asymmetric hand postures. Other structures of the deep flexors complex can be affected during this injury mechanism, due to the so-called quadriga effect, which can commonly occur during sport climbing practise. Biomechanical studies are needed to better understand the pathomechanism. A cadaveric study was designed to analyse the effects of load during the fourth lumbrical muscle injury mechanism. The amount of FDP tendon gliding and metacarpophalangeal (MCP) joint flexion of the 5th finger were calculated. Ten fresh-frozen cadaveric specimens (ten non-paired forearms and hands) were used. The specimens were placed on a custom-made loading apparatus. The FDP of the 5th finger was loaded, inducing isolated flexion of the 5th finger, until rupture. The rupture occurred in all specimens, under a load of 11 kg (SD 4.94), at 9.23 mm of proximal tendon gliding (SD 3.55) and at 21.4° (SD 28.91) of MCP joint flexion. Lumbrical muscle detachment from the 4th FDP was observed, from distal to proximal, and changes in FDP tendons at the distal forearm level too. The quadriga effect can lead to injury of the bipennate lumbrical muscles and the deep flexors complex in the hand and forearm.

The space–air–ground integrated network (SAGIN) represents a pivotal component within the realm of next-generation mobile communication technologies, owing to its established reliability and adaptable coverage capabilities. Central to the advancement of SAGIN is propagation channel research due to its critical role in aiding network system design and resource deployment. Nevertheless, real-world propagation channel research faces challenges in data collection, deployment, and testing. Consequently, this paper designs a comprehensive simulation framework tailored to facilitate SAGIN propagation channel research. The framework integrates the open source QuaDRiGa platform and the self-developed satellite channel simulation platform to simulate communication channels across diverse scenarios, and also integrates data processing, intelligent identification, algorithm optimization modules in a modular way to process the simulated data. We also provide a case study of scenario identification, in which typical channel features are extracted based on channel impulse response (CIR) data, and recognition models based on different artificial intelligence algorithms are constructed and compared.

IntroductionArthrodesis of the proximal interphalangeal (PIP) joint at 40° angle has been proposed by many authors. A smaller angle of arthrodesis results in weaker grip strength of the hand from the quadriga effect. However, arthrodesis at 40° compromises other aspects of hand function including poor aesthetic appearance. This paper aims to quantify the decrease in grip strength at 40°, 20°, and 0° of arthrodesis.Materials and methodsGrip strengths of the hand were measured using a BASELINE dynamometer at settings II, III, and IV. Baseline grip strength of the subjects were first measured without wearing a splint. Thereafter, subjects wore thermoplastic splints to simulate arthrodesis of the middle and ring finger PIP joint at 40°, 20°, and 0°, and grip strengths were measured again. The grip strength of the hand with simulated arthrodesis was then calculated as a ratio of the baseline.ResultsThere were 50 subjects yielding 100 sets of results. The results show that average grip strength ratio of the hand decreases progressively from 40° and 20° and to 0° of arthrodesis for both the middle and ring finger. However, the difference in grip strength ratio between 40° and 20° of arthrodesis was minimal. Simulated arthrodesis of the middle finger affected the grip strength ratio more than arthrodesis of the ring finger, and compromised gripping of a smaller handle more than a wider one.ConclusionThe decrease in grip strength from 40° to 20° simulated fusion of PIP joint was minimal. Therefore, in so far as grip strength loss is concerned, arthrodesis of the PIP joint at an angle less than 40° can be considered for patients with individual functional and aesthetic concerns.

A retrospective, single-center, consecutive case series. In concept, a relative motion flexion (RMF) orthosis will induce a “quadriga effect” on a given flexor digitorum profundus (FDP) tendon, limiting its excursion and force of flexion while still permitting a wide range of finger motion. This effect can be exploited in the rehabilitation of zone I and II FDP repairs. To describe the use of RMF orthoses to manage zone I and II FDP 4-strand repairs. Medical record review of 10 consecutive zone I and II FDP tendon repairs managed with RMF orthosis for 8 to 10 weeks in combination with a static dorsal blocking or wrist orthosis for the initial 3 weeks. Indications included sharp lacerations (n = 6), ragged lacerations (n = 2), staged flexor tendon reconstruction (n = 1), and type IV avulsion (n = 1). In 8 of the 10 cases that completed follow-up, the mean arc of proximal interphalangeal/distal interphalangeal active motion were as follows: sharp, 0° to 106°/0° to 75°; ragged, 0° to 90°/0° to 25°; reconstruction, 0° to 90°/10° to 45°; and avulsion, 0° to 95°/0° to 20°. Grip performance available for 6 of 10 cases was 62% to 108% of the dominant hand. There were no tendon ruptures, secondary surgeries, or proximal interphalangeal joint contractures. Based on this small series, the RMF approach appears to be safe and effective. It can lead to similar mobility and functional recovery as other early active motion protocols, with certain practical advantages and without major complications. Further investigation with larger, multicenter, prospective, longitudinal cohorts and/or randomized clinical trials is necessary. •Relative motion flexion orthoses used in rehabilitation of zones I/II FDP repairs.•No tendon ruptures and return to work average 9.5 weeks.•Compares favorably with other early active motion protocols.

Purpose: Production of a functional grip pattern requires the concerted action of numerous structures within the hand. This study quantifies the effect of total distal interphalangeal joint (DIPJ) stiffness to grip strength. Methods: Fifty (25 men, 25 women, 100 hands) individuals with a mean age of 38 years (range: 17-69 years) were recruited. Exclusion criteria included history of previous upper limb injury, neuropathies, or systemic disease. Custom thermoplastic orthoses were used to splint participants’ DIPJ in full extension simulating stiffness. Grip strength before and after splinting was measured using a calibrated Jamar dynamometer. Data were analyzed using paired and independent sample t tests and 2 × 2 repeated-measures analysis of variance with hand dominance and configuration (splinted or unsplinted) as within-subject factors. Results: Restriction of DIPJ flexion led to a 20% decrease in grip strength (P < .001). There was no significant difference in this decrease between dominant and non-dominant hands. Univariate analysis did not demonstrate any interaction between hand dominance and testing configuration. Post hoc analysis revealed no statistical difference in baseline grip strength between the dominant and non-dominant hands. Furthermore, men had significantly stronger grip strength than women in all configurations (P < .001). Conclusions: Flexion at the DIPJ contributes significantly to grip strength, and stiffness at this joint greatly limits functional capabilities of the hand. This necessitates the need for targeted rehabilitation in DIPJ injuries to minimize adverse effects on grip strength.

Des neuf recettes de poudre du quadrige transmises par les textes latins et grecs, utilisées pour fortifier les chevaux de course épuisés après un effort intense ou plus largement après une maladie ou pendant l’hiver, trois sont conservées par Végèce, Mulom. 3, 13 : celles nommément attribuées à Chiron et Absyrtus sont inédites, celle de Pélagonius, plus complète que Pelagon. 390. Végèce disposait de sources que nous n’avons pas ou qui ne nous sont pas parvenues dans l’état où il les consultait. Copieuses et coûteuses, les recettes inventées par les vétérinaires témoignent de leur rôle important dans le monde des hippodromes. Among the nine recipes of the quadriga’s powder transmitted by the latin and greek texts, used for strengthening race horses, worn out after a violent strain or more generaly after a disease or during the winter, three are preserved by Vegetius, Mulom. 3, 13 : those namely attributed to Chiron and Absyrtus are previously unseen, Pelagonius’one is more complete, than that of Pelagon. 390. Vegetius made use of sources lost to us or whose contents are not the same as those we have in hand. These substantial and expensive recipes invented by the veterinary surgeons give evidence of their prominent part in the race-course society.

Des neuf recettes de poudre du quadrige transmises par les textes latins et grecs, utilisées pour fortifier les chevaux de course épuisés après un effort intense ou plus largement après une maladie ou pendant l’hiver, trois sont conservées par Végèce, Mulom. 3, 13 : celles nommément attribuées à Chiron et Absyrtus sont inédites, celle de Pélagonius, plus complète que Pelagon. 390. Végèce disposait de sources que nous n’avons pas ou qui ne nous sont pas parvenues dans l’état où il les consultait. Copieuses et coûteuses, les recettes inventées par les vétérinaires témoignent de leur rôle important dans le monde des hippodromes.