In this paper we focus on the mutability of Non Fungible Tokens associated to digital assets in the metaverse. We argue that mutability is a key property of digital assets if we want to provide users ...with a virtual experience in the metaverse as close as possible to the real world. We discuss the shortcomings of current dynamic Non Fungible Token proposals, and present the advantages of a new mutable Non Fungible Token approach based on decoupling the asset ownership and descriptor in separate smart contracts. To show a possible usage of mutable Non Fungible Tokens in a metaverse, we provide a reference example about a university gadget. Finally, we present a proof of concept implementation of our reference example on the Decentraland metaverse and the Goerli Ethereum testnet to showcase its feasibility.
Abstract
The Hubble constant (
H
0
) tension between Type Ia supernovae (SNe Ia) and Planck measurements ranges from 4 to 6
σ
. To investigate this tension, we estimate
H
0
in the ΛCDM and
w
0
w
a
...CDM (cold dark matter) models by dividing the Pantheon sample, the largest compilation of SNe Ia, into 3, 4, 20, and 40 bins. We fit the extracted
H
0
values with a function mimicking the redshift evolution:
g
(
z
)
=
H
0
(
z
)
=
H
˜
0
/
(
1
+
z
)
α
, where
α
indicates an evolutionary parameter and
H
˜
0
=
H
0
at
z
= 0. We set the absolute magnitude of SNe Ia so that
H
0
=
73.5
km
s
−
1
Mpc
−
1
, and we fix fiducial values for
Ω
0
m
Λ
CDM
=
0.298
and
Ω
0
m
w
0
w
a
CDM
=
0.308
. We find that
H
0
evolves with redshift, showing a slowly decreasing trend, with
α
coefficients consistent with zero only from 1.2 to 2.0
σ
. Although the
α
coefficients are compatible with zero in 3
σ
, this however may affect cosmological results. We measure locally a variation of
H
0
(
z
=
0
)
−
H
0
(
z
=
1
)
=
0.4
km
s
−
1
Mpc
−
1
in three and four bins. Extrapolating
H
0
(
z
)
to
z
= 1100, the redshift of the last scattering surface, we obtain values of
H
0
compatible in 1
σ
with Planck measurements independent of the cosmological models and number of bins we investigated. Thus, we have reduced the
H
0
tension in the range from 54% to 72% for both cosmological models. If the decreasing trend of
H
0
(
z
)
is real, it could be due to astrophysical selection effects or to modified gravity.
The difference from 4 to 6 σ in the Hubble constant (H0) between the values observed with the local (Cepheids and Supernovae Ia, SNe Ia) and the high-z probes (Cosmic Microwave Background obtained by ...the Planck data) still challenges the astrophysics and cosmology community. Previous analysis has shown that there is an evolution in the Hubble constant that scales as f(z)=H0/(1+z)η, where H0 is H0(z=0) and η is the evolutionary parameter. Here, we investigate if this evolution still holds by using the SNe Ia gathered in the Pantheon sample and the Baryon Acoustic Oscillations. We assume H0=70kms−1Mpc−1 as the local value and divide the Pantheon into three bins ordered in increasing values of redshift. Similar to our previous analysis but varying two cosmological parameters contemporaneously (H0, Ω0m in the ΛCDM model and H0, wa in the w0waCDM model), for each bin we implement a Markov-Chain Monte Carlo analysis (MCMC) obtaining the value of H0 assuming Gaussian priors to restrict the parameters spaces to values we expect from our prior knowledge of the current cosmological models and to avoid phantom Dark Energy models with w<−1. Subsequently, the values of H0 are fitted with the model f(z). Our results show that a decreasing trend with η∼10−2 is still visible in this sample. The η coefficient reaches zero in 2.0 σ for the ΛCDM model up to 5.8 σ for w0waCDM model. This trend, if not due to statistical fluctuations, could be explained through a hidden astrophysical bias, such as the effect of stretch evolution, or it requires new theoretical models, a possible proposition is the modified gravity theories, f(R). This analysis is meant to further cast light on the evolution of H0 and it does not specifically focus on constraining the other parameters. This work is also a preparatory to understand how the combined probes still show an evolution of the H0 by redshift and what is the current status of simulations on GRB cosmology to obtain the uncertainties on the Ω0m comparable with the ones achieved through SNe Ia.
Background: The medial patellofemoral ligament (MPFL) is the primary passive restraint to lateral patellar dislocation and there is increasing awareness of its role in recurrent lateral patellar ...instability.
Purpose: This study was conducted to prospectively analyze the functional results of a modified MPFL reconstruction technique in recurrent patellar dislocation.
Study Design: Case series; Level of evidence, 4.
Methods: Forty-eight patients (51 knees) with at least 3 episodes of lateral patellar dislocation who had been treated with a 6-month rehabilitation protocol were included in this study. All patients practiced sports regularly. Reconstruction was with a semitendinosus tendon using a divergent 2-tunnel technique. Outcome was evaluated with the Kujala, Larsen, modified Lysholm, and Fulkerson outcome scores. Patient satisfaction with range of motion, pain, and sporting activities was also assessed.
Results: Three patients were lost at the final follow-up, giving a follow-up rate of 94%. The mean follow-up was 33 months. There was no patella dislocation postoperatively. The mean Kujala score improved significantly (P < .01) from 56.7 ± 17.7 (2 × standard deviation) preoperatively to 86.8 ± 14.4 postoperatively. The mean Larsen score improved significantly (P < .01) from 12.4 ± 3.2 to 17.1 ± 2.7. The mean Fulkerson score improved significantly (P < .01) from 59.2 ± 21.8 to 90.1 ± 14. The mean modified Lysholm score improved significantly (P < .01) from 57.6 ± 19.6 to 88.1 ± 16.2. Sixty-four percent of patients returned to the same type of sport at the same level, 16% reduced the level or type of sport for reasons unrelated to the surgery, while 20% reduced the level of sport or changed it for reasons related to surgery. Eighty-seven percent were either satisfied or very satisfied with the pain relief achieved. The patellar tilt decreased significantly from a preoperative mean of 11.1° to 8.9° at the last follow-up (P = .02). The mean preoperative Insall-Salvati ratio of 1.1 decreased to 1.06, although the change was not significant (P = .1).
Conclusion: The results of modified MPFL reconstructions are encouraging, with minimal risks of redislocation and an overall patient satisfaction rate of over 80%. These early and medium-term results are comparable with those of other MPFL reconstruction techniques reported in the literature.
Purpose
Bucket handle tears of the meniscus are common and can lead to locking, extension deficit and functional impairment. The diagnosis is determined by a combination of physical examination and ...imaging, but in some cases the diagnosis may be challenging since specific clinical tests are lacking. The aim of the present study was to assess the value of a new clinical test, the elective pain at the anterior aspect of the joint line (defined as the “Rising Moon sign”) in the diagnosis of bucket handle tears of the medial meniscus.
Methods
Forty patients treated for a bucket handle of the medial meniscus were enrolled as the study group and were compared to a matched group of 40 patients with a posterior horn tear of the medial meniscus and 50 healthy subjects. The following aspects were investigated in the groups: body mass index, extension deficit, pain at the posterior aspect of the joint line (PPJL), at the middle joint line (PMJL), at the anterior join line (PAJL) and at combined hyperflexion of the knee and external rotation of the foot (PHE). Pain at the anterior joint line (PAJL) was defined as the Rising Moon sign.
Results
In the bucket handle group the average flexion contracture was 12° (0–30°). The average PPJL was one (0–2), the average PMJL was 1.6 (0–3), PAJL was 2.5 (1–3) and PHE was 1.6 (1–2). In the posterior horn tear group the average flexion contracture was 0.9° (− 10 to 5°). The average PPJL was 2.2 (1–3), the average PMJL was 1.4 (0–3), PAJL was 0.6 (0–2) and PHE was 2.5 (1–3). The rising moon showed 95% sensitivity and 98% specificity in the diagnosis of bucket handle tears. In addition it showed a positive predictive value of 97.4% and negative predictive value of 96%. Finally it also demonstrated high inter-observer reliability (0.905).
Conclusions
The “Rising Moon” sign has shown to be highly predictive for bucket handle tears of the medial meniscus with very high specificity and sensitivity. In addition it is easy to perform with very high inter-observer reliability.
Level of evidence
Level IV.
•A Wearable Drowsiness Detector based on sensor fusion is presented.•EEG and IMU sensors are used to detect 5 levels of drowsiness with 95% of accuracy.•Efficient HW/FW co-design permits 6 hours of ...operation with a 200 mAh battery.•Further energy saving was investigated by porting the FW in a PULP platform.•Results shows a 63x gain in energy efficiency extending 7 times battery duration.
Drowsiness detection mechanisms have been extensively studied in the last years since they are one of the prevalent causes of accidents within the mining, driving and industrial activities. Many research efforts were done to quantify the drowsiness levels using behavioral analyses based on camera eye tracking systems as well as by analyzing physiological features contained in EEG signals. Detection systems typically use specific drowsiness indicators from only one of these methods, leaving a risk of missed detection since not all the population presents same symptoms of drowsiness. Thus, multi-feature systems are preferable even though most of the current State-of-the-Art (SoA) solutions are based on power-hungry platforms and they have meager chance to be used in embedded wearable applications with long battery lifetime. This work presents a drowsiness detection scheme fusing behavioral information coming from user motion through an IMU sensor and physiological information coming from brain activity through a single EEG electrode. The solution is implemented and tested on a low power programmable platform based on an ARM Cortex-M4 microcontroller, resulting in a wearable device capable to detect 5 different levels of drowsiness with an average accuracy of 95.2% and a battery life of 6 hours, using a 200 mAh battery. We also study the energy optimization achievable by accelerating the sensor fusion-based drowsiness detector on a parallel ultra-low power (PULP) platform. Results show that the use of PULP as efficient processing platform provides an energy improvement of 63x with respect to a solution based on a commercial microcontroller. This may extend the battery life of the complete system up to 46 h with a 7x improvement, paving the way for a completely wearable, always-on system.
Purpose
Proper rotational alignment of the femoral component is critical for a successful total knee arthroplasty (TKA). The aim of this systematic review was to analyse the available literature to ...examine the effect of the TKA femoral component malrotation on clinical outcomes and assess a cut-off value for femoral rotation leading to revision surgery.
Methods
A detailed and systematic search from 1996 to 2019 of the PUBMED, Medline, Cochrane Reviews and Google Scholar databases had been performed using the keyword terms “total knee arthroplasty OR replacement” AND “femoral alignment OR malalignment OR femoral rotation OR malrotation” AND “clinical outcome”. We used the methodological index for non-randomized studies (MINORS) to identify scientifically sound articles in a reproducible format.
Results
Eleven articles met inclusion criteria. A total of 896 arthroplasties were included in this review; 409 were unexplained painful TKA patients, while 487 were painless TKA patients. The mean age of patients was 67.5 (± 2.1) years. The mean post-operative follow-up delay was 46.8 (± 32.2) months. The mean of MINORS score was 21 points indicating good methodological quality in the included studies.
Conclusions
The present review confirms that the malrotation of the femoral component in TKA does not correlate automatically to poor clinical and functional outcome. The clinical relevance of this study was that, to improve accuracy in femoral component rotation, surgeons should consider the anatomical variability of femur in each knee and perform additional measurements pre- and intra-operatively. Taking a more accurate approach will shed light on unanswered questions in unhappy TKA.
Level of evidence
III.
Modular augmentation in revision total knee arthroplasty Panni, Alfredo Schiavone; Vasso, Michele; Cerciello, Simone
Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA,
12/2013, Letnik:
21, Številka:
12
Journal Article
Recenzirano
Purpose
Controversy exists about the real effectiveness of modular augmentation to manage bone defects in revision total knee arthroplasty. The purpose of this study was to determine whether use of ...modular augmentation to reconstruct severe defects (1) significantly increased overall outcomes, (2) caused radiolucency or osteolysis and (3) affected mid-term survivorship of knee revisions. The hypothesis was that modular augmentation provides a good survivorship of knee revisions.
Methods
Thirty-eight consecutive revision knee arthroplasties were followed for a median follow-up period of 7 (4.5–9) years. Type 2 and 3 defects were treated with metal augments, tantalum cones and modular cementless stems. Patients were assessed using the IKS knee and function scores and the HSS score.
Results
The median IKS knee and function scores and HSS score were 34 (15–58), 19.5 (13–39) and 30 (24–60) points before the operation, respectively, and 78 (49–97), 76 (58–90) and 80.5 (64–98) points (
p
< 0.001) at the latest follow-up. The median knee flexion increased from 82° (31°–110°) to 116° (100°–129°) (
p
< 0.01). Tibial radiolucencies were observed in 2 (5.2 %) cases. Re-revision was necessary in three (7.9 %) patients.
Conclusions
Modular augmentation may reduce the need for allografting to treat severe bone defects, providing a well-functioning and durable knee joint reconstruction.
Level of evidence
Case-series study, Level IV.
Acute patellar dislocation. What to do? Panni, Alfredo Schiavone; Vasso, Michele; Cerciello, Simone
Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA,
02/2013, Letnik:
21, Številka:
2
Journal Article
Recenzirano
Acute patellar dislocation is a common knee injury that occurs most often in adolescents, frequently associated with sporting and physical activities. Patellar re-dislocation after the first episode ...appears to depend primarily on the medial patellofemoral ligament injury which represents the primary ligamentous restraint, providing about 50–60 % of the restraining force against lateral patellar displacement. Clinically, up to 94–100 % of patients suffer from medial patellofemoral ligament rupture after first-time patellar dislocation. Controversy regarding how patients with first patellar dislocation should be managed still exists. Though most authors have reported good results with the conservative treatment after a first-time dislocation, several circumstances may warrant surgical intervention. A surgical approach would be necessary in the presence of severe cartilage damage or a relevant disruption of the medial stabilizers with subluxation of the patella. In these cases, the repair/reconstruction of medial stabilizers should follow the treatment of the chondral injury. Medial patellofemoral ligament reconstruction may be a more reliable method of stabilizing the patella than its repair, which has limitations related to the medial patellofemoral ligament injury location. Nowadays, there is no evidence available where osseous abnormalities should be addressed in addition to restoring the medial patellofemoral ligament.
Introduction
The management of bone loss is a crucial aspect of the revision knee arthroplasty. Bone loss can hinder the correct positioning and alignment of the prosthetic components, and can ...prevent the achievement of a stable bone–implant interface. There is still controversy regarding the optimal management of knee periprosthetic bone loss, especially in large defects for which structural grafts, metal or tantalum augments, tantalum cones, porous metaphyseal sleeves, and special prostheses have been advocated. The aim of this review was to analyze all possible causes of bone loss and the most advanced strategies for managing bony deficiency within the knee joint reconstruction.
Materials and methods
Most significant and recent papers about the management of bone defects during revision knee arthroplasty were carefully analyzed and reviewed to report the most common causes of bone loss and the most effective strategies to manage them.
Results
Modular metal and tantalum augmentation showed to provide more stable and durable knee revisions compared to allografts, limited by complications such as graft failure, fracture and resorption. Moreover, modular augmentation may considerably shorten operative times with a potential decrease of complications, above all infection which has been frequently associated to the use of allografts.
Conclusions
Modular augmentation may significantly reduce the need for allografting, whose complications appear to limit the long-term success of knee revisions.
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