Search for π0 decays to invisible particles Cortina Gil, E.; Minucci, E.; Padolski, S. ...
The journal of high energy physics,
02/2021, Letnik:
2021, Številka:
2
Journal Article
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A
bstract
The NA62 experiment at the CERN SPS reports a study of a sample of 4 × 10
9
tagged
π
0
mesons from
K
+
→
π
+
π
0
(
γ
), searching for the decay of the
π
0
to invisible particles. No signal ...is observed in excess of the expected background fluctuations. An upper limit of 4
.
4 × 10
−
9
is set on the branching ratio at 90% confidence level, improving on previous results by a factor of 60. This result can also be interpreted as a model- independent upper limit on the branching ratio for the decay
K
+
→
π
+
X
, where
X
is a particle escaping detection with mass in the range 0.110–0.155 GeV
/c
2
and rest lifetime greater than 100 ps. Model-dependent upper limits are obtained assuming
X
to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs boson.
Early P2P-TV systems have already attracted millions of users, and many new commercial solutions are entering this market. Little information is however available about how these systems work, due to ...their closed and proprietary design. In this paper, we present large scale experiments to compare three of the most successful P2P-TV systems, namely PPLive, SopCast and TVAnts. Our goal is to assess what level of "network awareness" has been embedded in the applications. We first define a general framework to quantify which network layer parameters leverage application choices, i.e., what parameters mainly drive the peer selection and data exchange. We then apply the methodology to a large dataset, collected during a number of experiments where we deployed about 40 peers in several European countries. From analysis of the dataset, we observe that TVAnts and PPLive exhibit a mild preference to exchange data among peers in the same autonomous system the peer belongs to, while this clustering effect is less intense in SopCast. However, no preference versus country, subnet or hop count is shown. Therefore, we believe that next-generation P2P live streaming applications definitively need to improve the level of network-awareness, so to better localize the traffic in the network and thus increase their network-friendliness as well.
Abstract
PADME (Positron Annihilation into Dark Matter Experiment) is a fixed target experiment located at the Beam Test Facility (BTF) at the Laboratori Nazionali di Frascati (LNF) designed to ...search for a massive dark photon
A
′
in the process
e
+
e
−
→
γ
A
′
, using a positron beam of energy up to 550 MeV. The experiment exploits the missing mass technique which allows for a search of
A
′
in a model independent way. A sensitivity on the mixing constant
ϵ
> 10
−3
for a dark photon mass in the range
1
≤
m
A
′
≤
23.7
MeV
/c
2
can be achieved by collecting 4 × 10
13
positrons on target. Run 2 data taking finished in December 2020 and allowed to reach an integrated luminosity of 5 × 10
12
positrons on target.
Highlights • mtDNA analysis is a molecular method to evaluate the clonality of secondary tumors. • mtDNA analysis differentiated 23 OSCCs in 7 LRs, 4 SPTs and 12 SFTs. • SFTs showed a better survival ...rate with respect to LRs and SPTs. • mtDNA analysis may influence the prognosis and treatment in multiple OSCCs.
Background and purpose
Mutations in the SACS gene are commonly associated with autosomal recessive spastic ataxia of Charlevoix‐Saguenay (ARSACS), a complex neurodegenerative disorder characterized ...by progressive degeneration of the cerebellum and spinal cord tracts. The aim of this study was to identify the genetic cause of the disease in an Italian family with spastic paraplegia and peripheral neuropathy.
Methods
Affected subjects were subjected to a comprehensive neurological examination including electromyography and brain magnetic resonance imaging. Genetic studies included exclusion of known disease genes, genome‐wide linkage analysis using high density single nucleotide polymorphism genotyping and candidate gene sequencing.
Results
Molecular analyses revealed a novel missense mutation in the SACS gene (c.11,104A>G) occurring in a homozygous state in patients and absent in 700 Italian control chromosomes. The mutation led to the amino acid substitution p.Thr3702Ala in the sacsin protein, in a possible protein−protein interaction site of UBE3A binding domain.
Conclusion
This study broadens the genetic spectrum of SACS mutations and expands the clinical ARSACS phenotype suggesting that the SACS gene can be considered in patients with non‐canonical ARSACS clinical presentations.
Autosomal dominant lateral temporal epilepsy (ADLTE) is characterized by focal seizures with auditory features or aphasia. Mutations in the LGI1 gene have been reported in up to 50% of ADLTE ...pedigrees. We report a family with temporal lobe epilepsy characterized by psychic symptoms associated with a novel LGI1 mutation.
All participants were personally interviewed and underwent neurologic examination and video-EEG recordings. LGI1 exons were sequenced by standard methods. Mutant cDNA was transfected into human embryonic kidney 293 cells; both cell lysates and media were analyzed by Western blot. In silico modeling of the Lgi1 protein EPTP domain was carried out using the structure of WD repeat protein and manually refined.
Three affected family members were ascertained, 2 of whom had temporal epilepsy with psychic symptoms (déjà vu, fear) but no auditory or aphasic phenomena, while the third had complex partial seizures without any aura. In all patients, we found a novel LGI1 mutation, Arg407Cys, which did not hamper protein secretion in vitro. Mapping of the mutation on a 3-dimensional protein model showed that this mutation does not induce large structural rearrangements but could destabilize interactions of Lgi1 with target proteins.
The Arg407Cys is the first mutation with no effect on Lgi1 protein secretion. The uncommon, isolated psychic symptoms associated with it suggests that ADLTE encompasses a wider range of auras of temporal origin than hitherto reported.
To elucidate the mechanism by which nerve growth factor (NGF) influences the LH secretory pathway in camelids, a series of experiments were done to determine the involvement of the hypothalamus ...(Experiment 1), the role of GnRH neurons (Experiment 2), and the effect of progesterone (Experiment 3) on the NGF-induced LH surge and ovulation in llamas. In Experiment 1, the declining phase of the NGF-induced LH surge was used to determine if the decline is a result of pituitary depletion or hypothalamic unresponsiveness. Female llamas were treated with NGF and, 7 h later, assigned to three groups and given a second dose of NGF (n = 5), a dose of GnRH (n = 5), or saline (n = 6). The LH response was attenuated after the second dose of NGF vs GnRH. In Experiment 2, Fos expression (marker of neuronal activation) in GnRH neurons was examined in the hypothalamus of llamas after NGF or saline treatment (n = 3 per group). Despite an LH surge in the NGF group but not in the saline group, no differences were detected between groups in Fos/GnRH co-expression. In Experiment 3, llamas in low-, medium-, and high-plasma progesterone groups (n = 4 per group) were treated with NGF. The NGF-induced LH surge did not differ among treatment groups. Results from the present study show that the induction of a preovulatory LH surge by NGF may be controlled by a novel pathway involving GnRH neuro-terminals downstream of the hypothalamus and is independent of progesterone influence.
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