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1.
Osteoporos Int ; 31(10): 1905-1912, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32440892

RESUMO

Patients with chronic kidney disease have high risk of osteoporotic fractures. Lower trabecular bone score (TBS) was associated with poorer kidney function and higher fracture risk when kidney function was normal. Addition of TBS to The Fracture Risk Assessment Tool with bone mineral density did not improve fracture risk prediction. INTRODUCTION: We sought to determine whether trabecular bone score (TBS) either independently or adjusted for The Fracture Risk Assessment Tool (FRAX) could predict risk of major osteoporotic fractures (MOFs) in a large population-based sample of patients with all stages of chronic kidney disease (CKD). METHODS: We used population-based administrative databases to identify patients above age 20 years who had dual-energy X-ray absorptiometry (DXA) scan and serum creatinine measured within 1 year, during the years 2005 to 2010. Patients were excluded if they were on dialysis or had a functioning renal transplant. We stratified patients by estimated glomerular filtration rate (eGFR). We collected femoral neck bone mineral density (BMD), lumbar spine TBS, incident major osteoporotic fractures (MOF) and hip fractures, and other clinical characteristics. RESULTS: Among 8289 patients, there were 6224 (75.1%) with eGFR ≥ 60 mL/min/1.73 m2, 1624 (19.6%) with eGFR 30-60 mL/min/1.73 m2, and 441 (5.3%) with eGFR < 30 mL/min/1.73 m2. There were 593 patients (7.2%) with MOFs and 163 (2.0%) with hip fractures. Lower TBS score was associated with increased risk of MOF and hip fractures across all eGFR strata in unadjusted Cox proportional hazards models but after adjusting for FRAX with BMD, lower TBS was only statistically significant for MOF prediction for eGFR ≥ 60 mL/min/1.73 m2. CONCLUSION: Lower TBS scores were associated with lower eGFR and increased fracture risk in patients with eGFR ≥ 60 mL/min/1.73 m2. However, the addition of TBS to the FRAX score with BMD did not significantly improve fracture risk prediction in patients with CKD.


Assuntos
Fraturas por Osteoporose , Insuficiência Renal Crônica , Absorciometria de Fóton , Adulto , Densidade Óssea , Osso Esponjoso/diagnóstico por imagem , Humanos , Vértebras Lombares , Fraturas por Osteoporose/epidemiologia , Fraturas por Osteoporose/etiologia , Insuficiência Renal Crônica/complicações , Insuficiência Renal Crônica/epidemiologia , Medição de Risco , Fatores de Risco , Adulto Jovem
2.
Phys Rev Lett ; 125(14): 141801, 2020 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-33064514

RESUMO

The results of a 3+1 sterile neutrino search using eight years of data from the IceCube Neutrino Observatory are presented. A total of 305 735 muon neutrino events are analyzed in reconstructed energy-zenith space to test for signatures of a matter-enhanced oscillation that would occur given a sterile neutrino state with a mass-squared differences between 0.01 and 100 eV^{2}. The best-fit point is found to be at sin^{2}(2θ_{24})=0.10 and Δm_{41}^{2}=4.5 eV^{2}, which is consistent with the no sterile neutrino hypothesis with a p value of 8.0%.

3.
Phys Rev Lett ; 125(12): 121104, 2020 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-33016752

RESUMO

We report on the first measurement of the astrophysical neutrino flux using particle showers (cascades) in IceCube data from 2010-2015. Assuming standard oscillations, the astrophysical neutrinos in this dedicated cascade sample are dominated (∼90%) by electron and tau flavors. The flux, observed in the sensitive energy range from 16 TeV to 2.6 PeV, is consistent with a single power-law model as expected from Fermi-type acceleration of high energy particles at astrophysical sources. We find the flux spectral index to be γ=2.53±0.07 and a flux normalization for each neutrino flavor of ϕ_{astro}=1.66_{-0.27}^{+0.25} at E_{0}=100 TeV, in agreement with IceCube's complementary muon neutrino results and with all-neutrino flavor fit results. In the measured energy range we reject spectral indices γ≤2.28 at ≥3σ significance level. Because of high neutrino energy resolution and low atmospheric neutrino backgrounds, this analysis provides the most detailed characterization of the neutrino flux at energies below ∼100 TeV compared to previous IceCube results. Results from fits assuming more complex neutrino flux models suggest a flux softening at high energies and a flux hardening at low energies (p value ≥0.06). The sizable and smooth flux measured below ∼100 TeV remains a puzzle. In order to not violate the isotropic diffuse gamma-ray background as measured by the Fermi Large Area Telescope, it suggests the existence of astrophysical neutrino sources characterized by dense environments which are opaque to gamma rays.

4.
Phys Rev Lett ; 124(5): 051103, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-32083934

RESUMO

This Letter presents the results from pointlike neutrino source searches using ten years of IceCube data collected between April 6, 2008 and July 10, 2018. We evaluate the significance of an astrophysical signal from a pointlike source looking for an excess of clustered neutrino events with energies typically above ∼1 TeV among the background of atmospheric muons and neutrinos. We perform a full-sky scan, a search within a selected source catalog, a catalog population study, and three stacked Galactic catalog searches. The most significant point in the northern hemisphere from scanning the sky is coincident with the Seyfert II galaxy NGC 1068, which was included in the source catalog search. The excess at the coordinates of NGC 1068 is inconsistent with background expectations at the level of 2.9σ after accounting for statistical trials from the entire catalog. The combination of this result along with excesses observed at the coordinates of three other sources, including TXS 0506+056, suggests that, collectively, correlations with sources in the northern catalog are inconsistent with background at 3.3σ significance. The southern catalog is consistent with background. These results, all based on searches for a cumulative neutrino signal integrated over the 10 years of available data, motivate further study of these and similar sources, including time-dependent analyses, multimessenger correlations, and the possibility of stronger evidence with coming upgrades to the detector.

5.
Phys Rev Lett ; 122(5): 051102, 2019 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-30822017

RESUMO

High-energy neutrino emission has been predicted for several short-lived astrophysical transients including gamma-ray bursts (GRBs), core-collapse supernovae with choked jets, and neutron star mergers. IceCube's optical and x-ray follow-up program searches for such transient sources by looking for two or more muon neutrino candidates in directional coincidence and arriving within 100 s. The measured rate of neutrino alerts is consistent with the expected rate of chance coincidences of atmospheric background events and no likely electromagnetic counterparts have been identified in Swift follow-up observations. Here, we calculate generic bounds on the neutrino flux of short-lived transient sources. Assuming an E^{-2.5} neutrino spectrum, we find that the neutrino flux of rare sources, like long gamma-ray bursts, is constrained to <5% of the detected astrophysical flux and the energy released in neutrinos (100 GeV to 10 PeV) by a median bright GRB-like source is <10^{52.5} erg. For a harder E^{-2.13} neutrino spectrum up to 30% of the flux could be produced by GRBs and the allowed median source energy is <10^{52} erg. A hypothetical population of transient sources has to be more common than 10^{-5} Mpc^{-3} yr^{-1} (5×10^{-8} Mpc^{-3} yr^{-1} for the E^{-2.13} spectrum) to account for the complete astrophysical neutrino flux.

6.
Phys Rev Lett ; 120(7): 071801, 2018 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-29542976

RESUMO

We present a measurement of the atmospheric neutrino oscillation parameters using three years of data from the IceCube Neutrino Observatory. The DeepCore infill array in the center of IceCube enables the detection and reconstruction of neutrinos produced by the interaction of cosmic rays in Earth's atmosphere at energies as low as ∼5 GeV. That energy threshold permits measurements of muon neutrino disappearance, over a range of baselines up to the diameter of the Earth, probing the same range of L/E_{ν} as long-baseline experiments but with substantially higher-energy neutrinos. This analysis uses neutrinos from the full sky with reconstructed energies from 5.6 to 56 GeV. We measure Δm_{32}^{2}=2.31_{-0.13}^{+0.11}×10^{-3} eV^{2} and sin^{2}θ_{23}=0.51_{-0.09}^{+0.07}, assuming normal neutrino mass ordering. These results are consistent with, and of similar precision to, those from accelerator- and reactor-based experiments.

7.
Eur J Vasc Endovasc Surg ; 54(2): 235-240, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28583719

RESUMO

OBJECTIVES: Acute lower limb ischaemia (ALLI) is a potentially fatal, limb threatening medical emergency. Early treatment is essential for a good outcome. The aim was to describe the early chain of care in ALLI focusing on lead times and emergency management in order to identify weak links for improvement. METHODS: This was a retrospective, descriptive case study. This study analysed the medical records of all patients with a main discharge diagnosis of ALLI between January 2009 and December 2014. Predetermined emergency care data on lead times, diagnosis recognition, presenting symptoms, emergency care treatment and outcome were collected for patients who were transported by the Emergency Medical Service (EMS) and those who were not. RESULTS: In total, 552 medical records were audited of which 195 patients fulfilled the inclusion criteria and were analysed. Among them were 117 (60%) transported by the EMS. The median time from symptom onset to revascularisation was 23 (interquartile range [IQR] 10-55; EMS transported) and 93 (IQR 42-152, not EMS transported) hours (p < .01). The time from symptom onset to arrival in hospital was 5 (IQR 2-26; EMS transported) and 48 (IQR 6-108; not EMS transported) hours. After arrival in hospital, the median time to first doctor evaluation was 51 (IQR 28-90; EMS transported) and 80 (IQR 44-169; not EMS transported) minutes, p = .01. Low molecular weight heparin (LMWH) was given to 72% of patients in the emergency department (ED) and a multivariate analysis showed that the use of LMWH was associated with a more favourable outcome. CONCLUSIONS: Both the time spent in the ED and the time from the onset of symptoms to revascularisation were considerably longer than optimal. Time delays in the early treatment chain can mainly be attributed to "patient delay" and a considerable time spent in hospital before revascularisation. The use of LMWH as an integral part of ED management was associated with a better outcome.


Assuntos
Anticoagulantes/administração & dosagem , Procedimentos Clínicos , Serviços Médicos de Emergência , Heparina de Baixo Peso Molecular/administração & dosagem , Isquemia/diagnóstico , Isquemia/terapia , Extremidade Inferior/irrigação sanguínea , Procedimentos Cirúrgicos Vasculares , Doença Aguda , Idoso , Idoso de 80 Anos ou mais , Esquema de Medicação , Diagnóstico Precoce , Feminino , Humanos , Isquemia/fisiopatologia , Salvamento de Membro , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Valor Preditivo dos Testes , Estudos Retrospectivos , Fatores de Risco , Fatores de Tempo , Tempo para o Tratamento , Resultado do Tratamento , Triagem , Procedimentos Cirúrgicos Vasculares/efeitos adversos
8.
Phys Rev Lett ; 117(24): 241101, 2016 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-28009216

RESUMO

We report constraints on the sources of ultrahigh-energy cosmic rays (UHECRs) above 10^{9} GeV, based on an analysis of seven years of IceCube data. This analysis efficiently selects very high- energy neutrino-induced events which have deposited energies from 5×10^{5} GeV to above 10^{11} GeV. Two neutrino-induced events with an estimated deposited energy of (2.6±0.3)×10^{6} GeV, the highest neutrino energy observed so far, and (7.7±2.0)×10^{5} GeV were detected. The atmospheric background-only hypothesis of detecting these events is rejected at 3.6σ. The hypothesis that the observed events are of cosmogenic origin is also rejected at >99% CL because of the limited deposited energy and the nonobservation of events at higher energy, while their observation is consistent with an astrophysical origin. Our limits on cosmogenic neutrino fluxes disfavor the UHECR sources having a cosmological evolution stronger than the star formation rate, e.g., active galactic nuclei and γ-ray bursts, assuming proton-dominated UHECRs. Constraints on UHECR sources including mixed and heavy UHECR compositions are obtained for models of neutrino production within UHECR sources. Our limit disfavors a significant part of parameter space for active galactic nuclei and new-born pulsar models. These limits on the ultrahigh-energy neutrino flux models are the most stringent to date.

9.
Phys Rev Lett ; 117(7): 071801, 2016 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-27563950

RESUMO

The IceCube neutrino telescope at the South Pole has measured the atmospheric muon neutrino spectrum as a function of zenith angle and energy in the approximate 320 GeV to 20 TeV range, to search for the oscillation signatures of light sterile neutrinos. No evidence for anomalous ν_{µ} or ν[over ¯]_{µ} disappearance is observed in either of two independently developed analyses, each using one year of atmospheric neutrino data. New exclusion limits are placed on the parameter space of the 3+1 model, in which muon antineutrinos experience a strong Mikheyev-Smirnov-Wolfenstein-resonant oscillation. The exclusion limits extend to sin^{2}2θ_{24}≤0.02 at Δm^{2}∼0.3 eV^{2} at the 90% confidence level. The allowed region from global analysis of appearance experiments, including LSND and MiniBooNE, is excluded at approximately the 99% confidence level for the global best-fit value of |U_{e4}|^{2}.

10.
Mol Cell Neurosci ; 66(Pt A): 3-11, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25748120

RESUMO

Inherited variants in multiple different genes are associated with increased risk for Alzheimer's disease (AD). In many of these genes, the inherited variants alter some aspect of the production or clearance of the neurotoxic amyloid ß-peptide (Aß). Thus missense, splice site or duplication mutants in the presenilin 1 (PS1), presenilin 2 (PS2) or the amyloid precursor protein (APP) genes, which alter the levels or shift the balance of Aß produced, are associated with rare, highly penetrant autosomal dominant forms of Familial Alzheimer's Disease (FAD). Similarly, the more prevalent late-onset forms of AD are associated with both coding and non-coding variants in genes such as SORL1, PICALM and ABCA7 that affect the production and clearance of Aß. This review summarises some of the recent molecular and structural work on the role of these genes and the proteins coded by them in the biology of Aß. We also briefly outline how the emerging knowledge about the pathways involved in Aß generation and clearance can be potentially targeted therapeutically. This article is part of Special Issue entitled "Neuronal Protein".


Assuntos
Doença de Alzheimer/metabolismo , Doença de Alzheimer/terapia , Peptídeos beta-Amiloides/metabolismo , Transdução de Sinais/fisiologia , Pesquisa Translacional Biomédica , Doença de Alzheimer/genética , Animais , Humanos
11.
Phys Rev Lett ; 115(8): 081102, 2015 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-26340177

RESUMO

Results from the IceCube Neutrino Observatory have recently provided compelling evidence for the existence of a high energy astrophysical neutrino flux utilizing a dominantly Southern Hemisphere data set consisting primarily of ν(e) and ν(τ) charged-current and neutral-current (cascade) neutrino interactions. In the analysis presented here, a data sample of approximately 35,000 muon neutrinos from the Northern sky is extracted from data taken during 659.5 days of live time recorded between May 2010 and May 2012. While this sample is composed primarily of neutrinos produced by cosmic ray interactions in Earth's atmosphere, the highest energy events are inconsistent with a hypothesis of solely terrestrial origin at 3.7σ significance. These neutrinos can, however, be explained by an astrophysical flux per neutrino flavor at a level of Φ(E(ν))=9.9(-3.4)(+3.9)×10(-19) GeV(-1) cm(-2) sr(-1) s(-1)(E(ν)/100 TeV(-2), consistent with IceCube's Southern-Hemisphere-dominated result. Additionally, a fit for an astrophysical flux with an arbitrary spectral index is performed. We find a spectral index of 2.2(-0.2)(+0.2), which is also in good agreement with the Southern Hemisphere result.

12.
Phys Rev Lett ; 114(17): 171102, 2015 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-25978221

RESUMO

A diffuse flux of astrophysical neutrinos above 100 TeV has been observed at the IceCube Neutrino Observatory. Here we extend this analysis to probe the astrophysical flux down to 35 TeV and analyze its flavor composition by classifying events as showers or tracks. Taking advantage of lower atmospheric backgrounds for showerlike events, we obtain a shower-biased sample containing 129 showers and 8 tracks collected in three years from 2010 to 2013. We demonstrate consistency with the (fe:fµ:fτ)⊕≈(1:1:1)⊕ flavor ratio at Earth commonly expected from the averaged oscillations of neutrinos produced by pion decay in distant astrophysical sources. Limits are placed on nonstandard flavor compositions that cannot be produced by averaged neutrino oscillations but could arise in exotic physics scenarios. A maximally tracklike composition of (0:1:0)⊕ is excluded at 3.3σ, and a purely showerlike composition of (1:0:0)⊕ is excluded at 2.3σ.

13.
Phys Rev Lett ; 113(10): 101101, 2014 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-25238345

RESUMO

A search for high-energy neutrinos interacting within the IceCube detector between 2010 and 2012 provided the first evidence for a high-energy neutrino flux of extraterrestrial origin. Results from an analysis using the same methods with a third year (2012-2013) of data from the complete IceCube detector are consistent with the previously reported astrophysical flux in the 100 TeV-PeV range at the level of 10(-8) GeV cm-2 s-1 sr-1 per flavor and reject a purely atmospheric explanation for the combined three-year data at 5.7σ. The data are consistent with expectations for equal fluxes of all three neutrino flavors and with isotropic arrival directions, suggesting either numerous or spatially extended sources. The three-year data set, with a live time of 988 days, contains a total of 37 neutrino candidate events with deposited energies ranging from 30 to 2000 TeV. The 2000-TeV event is the highest-energy neutrino interaction ever observed.

14.
Phys Rev Lett ; 110(13): 131302, 2013 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-23581307

RESUMO

We have performed a search for muon neutrinos from dark matter annihilation in the center of the Sun with the 79-string configuration of the IceCube neutrino telescope. For the first time, the DeepCore subarray is included in the analysis, lowering the energy threshold and extending the search to the austral summer. The 317 days of data collected between June 2010 and May 2011 are consistent with the expected background from atmospheric muons and neutrinos. Upper limits are set on the dark matter annihilation rate, with conversions to limits on spin-dependent and spin-independent scattering cross sections of weakly interacting massive particles (WIMPs) on protons, for WIMP masses in the range 20-5000 GeV/c2. These are the most stringent spin-dependent WIMP-proton cross section limits to date above 35 GeV/c2 for most WIMP models.

15.
Phys Rev Lett ; 111(8): 081801, 2013 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-24010427

RESUMO

We present the first statistically significant detection of neutrino oscillations in the high-energy regime (>20 GeV) from an analysis of IceCube Neutrino Observatory data collected in 2010 and 2011. This measurement is made possible by the low-energy threshold of the DeepCore detector (~20 GeV) and benefits from the use of the IceCube detector as a veto against cosmic-ray-induced muon background. The oscillation signal was detected within a low-energy muon neutrino sample (20-100 GeV) extracted from data collected by DeepCore. A high-energy muon neutrino sample (100 GeV-10 TeV) was extracted from IceCube data to constrain systematic uncertainties. The disappearance of low-energy upward-going muon neutrinos was observed, and the nonoscillation hypothesis is rejected with more than 5σ significance. In a two-neutrino flavor formalism, our data are best described by the atmospheric neutrino oscillation parameters |Δm(32)(2)|=(2.3(-0.5)(+0.6))×10(-3) eV(2) and sin(2)(2θ(23))>0.93, and maximum mixing is favored.

16.
Phys Rev Lett ; 111(2): 021103, 2013 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-23889381

RESUMO

We report on the observation of two neutrino-induced events which have an estimated deposited energy in the IceCube detector of 1.04±0.16 and 1.14±0.17 PeV, respectively, the highest neutrino energies observed so far. These events are consistent with fully contained particle showers induced by neutral-current ν(e,µ,τ) (ν(e,µ,τ)) or charged-current ν(e) (ν(e)) interactions within the IceCube detector. The events were discovered in a search for ultrahigh energy neutrinos using data corresponding to 615.9 days effective live time. The expected number of atmospheric background is 0.082±0.004(stat)(-0.057)(+0.041)(syst). The probability of observing two or more candidate events under the atmospheric background-only hypothesis is 2.9×10(-3) (2.8σ) taking into account the uncertainty on the expected number of background events. These two events could be a first indication of an astrophysical neutrino flux; the moderate significance, however, does not permit a definitive conclusion at this time.

17.
Phys Rev Lett ; 110(15): 151105, 2013 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-25167245

RESUMO

We report the first measurement of the atmospheric electron neutrino flux in the energy range between approximately 80 GeV and 6 TeV, using data recorded during the first year of operation of IceCube's DeepCore low-energy extension. Techniques to identify neutrinos interacting within the DeepCore volume and veto muons originating outside the detector are demonstrated. A sample of 1029 events is observed in 281 days of data, of which 496±66(stat)±88(syst) are estimated to be cascade events, including both electron neutrino and neutral current events. The rest of the sample includes residual backgrounds due to atmospheric muons and charged current interactions of atmospheric muon neutrinos. The flux of the atmospheric electron neutrinos is consistent with models of atmospheric neutrinos in this energy range. This constitutes the first observation of electron neutrinos and neutral current interactions in a very large volume neutrino telescope optimized for the TeV energy range.

18.
Phys Rev Lett ; 106(14): 141101, 2011 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-21561178

RESUMO

IceCube has become the first neutrino telescope with a sensitivity below the TeV neutrino flux predicted from gamma-ray bursts if gamma-ray bursts are responsible for the observed cosmic-ray flux above 10(18) eV. Two separate analyses using the half-complete IceCube detector, one a dedicated search for neutrinos from pγ interactions in the prompt phase of the gamma-ray burst fireball and the other a generic search for any neutrino emission from these sources over a wide range of energies and emission times, produced no evidence for neutrino emission, excluding prevailing models at 90% confidence.

19.
Phys Rev Lett ; 103(22): 221102, 2009 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-20366087

RESUMO

Point source searches with the IceCube neutrino telescope have been restricted to one hemisphere, due to the exclusive selection of upward going events as a way of rejecting the atmospheric muon background. We show that the region above the horizon can be included by suppressing the background through energy-sensitive cuts. This improves the sensitivity above PeV energies, previously not accessible for declinations of more than a few degrees below the horizon due to the absorption of neutrinos in Earth. We present results based on data collected with 22 strings of IceCube, extending its field of view and energy reach for point source searches. No significant excess above the atmospheric background is observed in a sky scan and in tests of source candidates. Upper limits are reported, which for the first time cover point sources in the southern sky up to EeV energies.

20.
Science ; 261(5123): 899-902, 1993 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-17783738

RESUMO

A new approach is described for probing domains of ordered self-assemblies of amphiphilic monolayers at the aqueous solution interface. The method has potential importance for the study of membrane structure, Langmuir-Blodgett films, and nucleation processes of two-and three-dimensional crystals. Electron diffraction (ED) patterns indicative of two-dimensional crystalline self-assembly were obtained from samples, which were examined by cryo-electron microscopy, of monolayers of water-insoluble amphiphiles on vitrified aqueour substrates. The apparent hexagonal symmetry of an ED pattern from a C(16)H(33)OH monolayer was interpreted in terms of multiple twinning. Monolayers of the CL(31)H(63)OH and cadmium salt of C(19)H(39)CO(2)H that were studied by dark-field techniques displayed faceted two-dimensional crystallites with a maximal size of 1 to 2 micrometers. Epitaxial nucleation of hexagonal ice by the C(31)H(63)OH monolayer has also been demonstrated by ED.

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