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1.
Phys Rev Lett ; 126(1): 017201, 2021 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-33480800

RESUMO

We apply neutron spectroscopy to measure the magnetic dynamics in the S=3/2 magnet ß-CaCr_{2}O_{4} (T_{N}=21 K). The low-energy fluctuations, in the ordered state, resemble large-S linear spin waves from the incommensurate ground state. However, at higher energy transfers, these semiclassical and harmonic dynamics are replaced by an energy and momentum broadened continuum of excitations. Applying kinematic constraints required for energy and momentum conservation, sum rules of neutron scattering, and comparison against exact diagonalization calculations, we show that the dynamics at high-energy transfers resemble low-S one-dimensional quantum fluctuations. ß-CaCr_{2}O_{4} represents an example of a magnet at the border between classical Néel and quantum phases, displaying dual characteristics.

2.
Proc Natl Acad Sci U S A ; 115(27): 6995-6999, 2018 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-29915042

RESUMO

A phase transition occurs when correlated regions of a new phase grow to span the system and the fluctuations within the correlated regions become long lived. Here, we present neutron scattering measurements showing that this conventional picture must be replaced in YFe2Al10, a compound that forms naturally very close to a [Formula: see text] quantum phase transition. Fully quantum mechanical fluctuations of localized moments are found to diverge at low energies and temperatures; however, the fluctuating moments are entirely without spatial correlations. Zero temperature order in YFe2Al10 is achieved by an entirely local type of quantum phase transition that may originate with the creation of the moments themselves.

3.
BJOG ; 127(10): 1200-1209, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32145139

RESUMO

OBJECTIVE: To examine the associations of maternal and child overweight status across multiple time-points with liver fat content in the offspring during young adulthood. DESIGN: Cohort study. SETTING: ELEMENT Cohort in Mexico City. POPULATION: Pregnant women with singleton births (n = 97). METHODS: We quantified hepatic triglyceride content (liver fat content) by proton magnetic resonance spectroscopy (1H MRS) and conventional T2-weighted MRIs (3T scanner) in 97 young adults from the ELEMENT birth cohort in Mexico City. Historical records of the cohort were used as a source of pregnancy, and childhood and adolescence anthropometric information, overweight and obesity (OWOB) were defined. Adjusted structural equation models were run to identify the association between OWOB in different life stages with liver fat content (log-transformed) in young adulthood. MAIN OUTCOME: Maternal OWOB at the time of delivery was directly and indirectly associated with the liver fat content in the offspring at young adulthood. RESULTS: Seventeen percent of the participants were classified as having NAFLD. We found a strong association of OWOB between all periods assessed. Maternal OWOB at time of delivery (ß = 1.97, 95% CI 1.28-3.05), and OWOB status in the offspring at young adulthood (ß = 3.17, 95% CI 2.10-4.77) were directly associated with the liver fat content in the offspring. Also, maternal OWOB was indirectly associated with liver fat content through offspring OWOB status. CONCLUSION: We found that maternal OWOB status is related to fatty liver content in the offspring as young adults, even after taking into account OWOB status and lifestyle factors in the offspring. TWEETABLE ABSTRACT: There was an association between pre-pregnancy overweight and the development of NAFLD in adult offspring.


Assuntos
Hepatopatia Gordurosa não Alcoólica/epidemiologia , Obesidade/epidemiologia , Complicações na Gravidez/epidemiologia , Adolescente , Adulto , Peso ao Nascer , Índice de Massa Corporal , Estudos de Casos e Controles , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , México/epidemiologia , Hepatopatia Gordurosa não Alcoólica/etiologia , Gravidez , Efeitos Tardios da Exposição Pré-Natal/epidemiologia , Triglicerídeos/análise , Adulto Jovem
4.
Phys Rev Lett ; 121(8): 087201, 2018 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-30192563

RESUMO

RbFe^{2+}Fe^{3+}F_{6} is an example of a charge ordered antiferromagnet where iron sites, with differing valences, are structurally separated into two interpenetrating sublattices. The low temperature magnetically ordered Fe^{2+} (S=2) and Fe^{3+} (S=5/2) moments form a noncollinear orthogonal structure with the Fe^{3+} site displaying a reduced static ordered moment. Neutron spectroscopy on single crystals finds two distinct spin wave branches with a dominant coupling along the Fe^{3+} chain axis (b axis). High resolution spectroscopic measurements find an intense energy and momentum broadened magnetic band of scattering bracketing a momentum-energy region where two magnon processes are kinematically allowed. These anharmonic excitations are enhanced in this noncollinear magnet owing to the orthogonal spin arrangement.

5.
Phys Rev Lett ; 121(3): 037003, 2018 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-30085774

RESUMO

CeCo(In_{0.990}Hg_{0.010})_{5} is a charge doped variant of the d-wave CoCoIn_{5} superconductor with coexistent antiferromagnetic and superconducting transitions occurring at T_{N}=3.4 and T_{c}=1.4 K, respectively. We use neutron diffraction and spectroscopy to show that the magnetic resonant fluctuations present in the parent superconducting phase are replaced by collinear c-axis magnetic order with three-dimensional Ising critical fluctuations. No low-energy transverse spin fluctuations are observable in this doping-induced antiferromagnetic phase and the dynamic resonant spectral weight predominately shifts to the elastic channel. Static (τ>0.2 ns) collinear Ising order is proximate to superconductivity in CeCoIn_{5} and is stabilized through hole doping with Hg.

6.
Phys Rev Lett ; 119(25): 257204, 2017 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-29303328

RESUMO

CaFe_{2}O_{4} is an anisotropic S=5/2 antiferromagnet with two competing A (↑↑↓↓) and B (↑↓↑↓) magnetic order parameters separated by static antiphase boundaries at low temperatures. Neutron diffraction and bulk susceptibility measurements, show that the spins near these boundaries are weakly correlated and a carry an uncompensated ferromagnetic moment that can be tuned with a magnetic field. Spectroscopic measurements find these spins are bound with excitation energies less than the bulk magnetic spin waves and resemble the spectra from isolated spin clusters. Localized bound orphaned spins separate the two competing magnetic order parameters in CaFe_{2}O_{4}.

7.
Phys Rev Lett ; 117(1): 017201, 2016 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-27419585

RESUMO

CaFe_{2}O_{4} is a S=5/2 anisotropic antiferromagnet based upon zig-zag chains having two competing magnetic structures, denoted as the A (↑↑↓↓) and B (↑↓↑↓) phases, which differ by the c-axis stacking of ferromagnetic stripes. We apply neutron scattering to demonstrate that the competing A and B phase order parameters result in magnetic antiphase boundaries along c which freeze on the time scale of ∼1 ns at the onset of magnetic order at 200 K. Using high resolution neutron spectroscopy, we find quantized spin wave levels and measure 9 such excitations localized in regions ∼1-2 c-axis lattice constants in size. We discuss these in the context of solitary magnons predicted to exist in anisotropic systems. The magnetic anisotropy affords both competing A+B orders as well as localization of spin excitations in a classical magnet.

8.
Phys Rev Lett ; 114(24): 247005, 2015 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-26197000

RESUMO

CeRhIn(5) is an itinerant magnet where the Ce(3+) spins order in a simple helical phase. We investigate the spin excitations and observe sharp spin waves parameterized by a nearest-neighbor exchange, J(RKKY)=0.88±0.05 meV. At higher energies, the spin fluctuations are heavily damped, where single-quasiparticle excitations are replaced by a momentum- and energy-broadened continuum constrained by kinematics of energy and momentum conservation. The delicate energy balance between localized and itinerant characters results in the breakdown of the single-quasiparticle picture in CeRhIn(5).

9.
Phys Rev Lett ; 112(2): 027202, 2014 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-24484043

RESUMO

Inelastic neutron scattering at low temperatures T≤30 K from a powder of LiZn2Mo3O8 demonstrates this triangular-lattice antiferromagnet hosts collective magnetic excitations from spin-1/2 Mo3O13 molecules. Apparently gapless (Δ<0.2 meV) and extending at least up to 2.5 meV, the low-energy magnetic scattering cross section is surprisingly broad in momentum space and involves one-third of the spins present above 100 K. The data are compatible with the presence of valence bonds involving nearest-neighbor and next-nearest-neighbor spins forming a disordered or dynamic state.

10.
J Dairy Sci ; 97(1): 185-94, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24183690

RESUMO

The objectives of this study were to evaluate effects of 2 resynchronization protocols beginning at different intervals after artificial insemination (AI) on the pattern of return to estrus, ovarian responses, and pregnancy per AI (P/AI) to reinsemination. Lactating cows from 2 dairies, located in Texas (n=2,233) and Minnesota (n=3,077), were assigned to 1 of 4 timed AI (TAI) protocols 17 ± 3 d after AI. All cows were examined for pregnancy 31 ± 3 d after previous AI. Cows assigned to early Ovsynch56 (E-OV56) or OV56 received the Ovsynch56 protocol starting 24 or 31 d after AI, respectively. Cows assigned to early GnRH-GnRH-PGF(2α)-GnRH (E-GGPG) or GGPG received a presynchronizing GnRH injection 17 or 24 d after AI, respectively, 7 d before the start of the Ovsynch56 protocol. Cows observed in estrus after enrollment were inseminated on the same day. Ovaries were examined and blood was sampled for progesterone concentration on the day of first GnRH and PGF(2α) injection of the Ovsynch56 protocol. Pregnancy was diagnosed at 31 and 66 d after resynchronized AI. On the day of the first GnRH injection of the TAI, a higher percentage of cows on E-GGPG and GGPG protocols had a corpus luteum (E-GGPG=83.8, GGPG=91.2, E-OV56=80.4, and OV56=75.5%) and progesterone concentration >1 ng/mL (E-GGPG=62.5, GGPG=76.0, E-OV56=53.6, and OV56=60.8%) than cows assigned to other protocols. However, the percentage of cows ovulating to the first GnRH injection of TAI was not affected by treatment. Fewer E-GGPG and more OV56 cows were reinseminated in estrus (E-GGPG=23.7, GGPG=49.0, E-OV56=41.6, and OV56=57.6%). Treatment did not affect P/AI at 31 or 66 d for cows reinseminated in estrus. However, cows reinseminated in estrus had greater P/AI at 31 (40.0 vs. 27.5%) and 66 d (36.0 vs. 23.9%) than cows completing the TAI protocols. Among cows completing the TAI protocols, initiation of GGPG at 24 d after AI increased, whereas initiation of Ovsynch56 at 24 d after AI decreased P/AI at 31 d after reinsemination (E-GGPG=30.6, GGPG=28.3.0, E-OV56=22.3, and OV56=28.7%). Pregnancy per AI did not differ across treatment at 66 d after TAI (E-GGPG=26.6, GGPG=24.4, E-OV56=20.0, and OV56=24.1%). Overall, type of resynchronization protocol and protocol initiation time did not affect P/AI 66 d after reinsemination (E-GGPG=29.7, GGPG=30.5, E-OV56=26.1, and OV56=30.4%). In conclusion, GGPG resynchronization protocols and initiation of resynchronization protocol 24 d after AI reduced the number of cows reinseminated in estrus but neither the timing of initiation of resynchronization nor presynchronization with GnRH affected overall P/AI.


Assuntos
Sincronização do Estro/métodos , Fertilidade/efeitos dos fármacos , Hormônio Liberador de Gonadotropina/farmacologia , Injeções/métodos , Lactação/efeitos dos fármacos , Animais , Bovinos , Corpo Lúteo/efeitos dos fármacos , Dieta/veterinária , Estro/efeitos dos fármacos , Sincronização do Estro/efeitos dos fármacos , Feminino , Fertilidade/fisiologia , Inseminação Artificial/veterinária , Lactação/fisiologia , Modelos Logísticos , Minnesota , Ovário/efeitos dos fármacos , Ovulação/efeitos dos fármacos , Ovulação/fisiologia , Gravidez , Progesterona/sangue , Texas
11.
J Dairy Sci ; 96(3): 1556-67, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23295117

RESUMO

The objective was to evaluate the effects of GnRH or PGF(2α)-based synchronization and resynchronization programs on fertility in lactating dairy cows. For experiment 1, cows (n=1,521) were presynchronized with 2 injections of PGF given at 36 and 50 DIM and assigned to 1 of 3 protocols: Ovsynch [OVS; n=552; GnRH injection, PGF(2α) injection 7 d later, GnRH injection 56 h later, and timed artificial insemination (TAI) 16 h later] beginning at 14 d after presynchronization (PS), GnRH-GnRH-PGF(2α)-GnRH (GGPG; n=402) treatment with a GnRH injection given 7 d after PS and OVS 7 d later, or PGF(2α)-GnRH-PGF(2α)-GnRH (P7GPG; n=567) treatment with a PGF(2α) injection given 7 d after PS and OVS beginning 7 d later. Experiment 2 cows (n=2,327) were assigned to 1 of 3 resynchronization protocols 7 d before nonpregnancy diagnosis (NPD): GGPG cows (n=458) received a GnRH injection at enrollment and OVS at NPD; P7GPG cows (n=940) received a PGF(2α) injection at NPD and OVS 7 d later; and P11GPG cows (n=929) received a PGF(2α) injection 3 d after NPD and OVS 11 d later. In both experiments, cows were artificially inseminated upon estrus detection (ED). In experiment 1, 52.3% of cows were artificially inseminated upon ED, with GGPG having reduced ED (GGPG=46.8 vs. OVS=50.7 and P7GPG=57.7%). Treatments did not affect overall pregnancy per artificial insemination (P/AI) at 36 and 66 d after AI (OVS=34.1 and 32.3, P7GPG=34.6 and 31.9, and GGPG=31.3 and 28.1%, respectively) or pregnancy loss but cows artificially inseminated upon ED had higher P/AI than cows undergoing TAI (ED cows=37.9 vs. TAI cows=28.8%). Treatment did not affect P/AI for cows artificially inseminated upon ED or TAI at 36 and 66 d after AI (OVS=34.1 and 32.3, P7GPG=34.6 and 31.9, and GGPG=31.3 and 28.1%). Median days in milk at first AI was affected by treatment (P7GPG=59 vs. OVS=68 and GGPG=68 d). In experiment 2, GGPG reduced ED (GGPG=23.3 vs. P7GPG=74.9 and P11GPG=79.6%). Treatment did not affect overall P/AI at 36 and 66 d after AI (GGPG=29.2 and 25.8, P7GPG=28.7 and 26.6, and P11GPG=31.9 and 30.2%) or pregnancy loss. Cows artificially inseminated upon ED had greater P/AI than TAI cows (ED=32.3 and TAI=25.1%). However, treatment did not affect P/AI for cows artificially inseminated upon ED at 36 and 66 d after AI (GGPG=29.6 and 27.3, P7GPG=29.4 and 28.1, and P11GPG=35.7 and 33.7%) or TAI (GGPG=29.1 and 25.3, P7GPG=25.0 and 22.1, and P11GPG=16.9 and 16.9%). Median days between NPD and AI was affected by treatment (GGPG=10 vs. P7GPG=4 and P11GPG=7 d). Prostaglandin-based programs increased ED and reduced interval to first AI and between AI. Gonadotropin-releasing hormone-based programs increased the proportion of TAI cows. Cows artificially inseminated upon ED had increased P/AI compared with TAI cows.


Assuntos
Bovinos/fisiologia , Dinoprosta/farmacologia , Sincronização do Estro/métodos , Hormônio Liberador de Gonadotropina/farmacologia , Inseminação Artificial/veterinária , Animais , Detecção do Estro/métodos , Sincronização do Estro/fisiologia , Feminino , Inseminação Artificial/métodos , Lactação/efeitos dos fármacos , Lactação/fisiologia , Paridade/efeitos dos fármacos , Paridade/fisiologia , Gravidez/efeitos dos fármacos , Gravidez/fisiologia
12.
Steroids ; 197: 109256, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37217088

RESUMO

Diosgenin and its derivatives have proved a huge importance in diverse biological activities. The optimized production of the diastereoisomers of the epoxide of diosgenin acetate by means of mCPBA is reported herein. This transformation had a previous design of experiments using the application of a statistical factorial DoE of 4 parameters (nk), where one variable is varied at a time, while others stay constant. The temperature showed the greatest effect on the reaction yield; so, at 298 K the diastereomeric ratio 3:1 of α and ß-epoxides, normally found, was raised to 1:1. Time was the second significant variable, but due to its high correlation with temperature, 30 min were required for a global 90% conversion at least. These diastereoisomers were characterized both isolated and in the mixtures obtained, to determine their antioxidant, antimicrobial and antiproliferative activity, finding a low antioxidant capacity by DPPH, but antimicrobial activity at the level of penicillin in gram negative bacteria by 1ß better to 1α. The antiproliferative capacity was higher for diastereoisomer ß, agreeing with the proportion of the mixture obtained by different conditions, increasing this in relation to the amount of this diastereoisomer present in hormone-dependent cancer cell lines such as Hela, PC-3 and MCF-7, with 10.0 µM obtained values of viability at 21.8 %, 35.8 % and 12.3 % respectively. DoE optimization allows to manipulate the ratio between diastereoisomers with the minimum number of experiments, extending the analysis of the effect of the ratio between diastereoisomers and the in silico potential as well as the biological activity.


Assuntos
Anti-Infecciosos , Diosgenina , Humanos , Antioxidantes/farmacologia , Antioxidantes/química , Diosgenina/química , Linhagem Celular Tumoral , Anti-Infecciosos/química , Células HeLa
13.
Phys Rev Lett ; 108(10): 107002, 2012 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-22463442

RESUMO

Using polarized and unpolarized neutron scattering, we show that interstitial Fe in superconducting Fe(1+y)Te(1-x)Se(x) induces a magnetic Friedel-like oscillation that diffracts at Q⊥=(1/2 0) and involves >50 neighboring Fe sites. The interstitial >2µ(B) moment is surrounded by compensating ferromagnetic four-spin clusters that may seed double stripe ordering in Fe(1+y)Te. A semimetallic five-band model with (1/2 1/2) Fermi surface nesting and fourfold symmetric superexchange between interstitial Fe and two in-plane nearest neighbors largely accounts for the observed diffraction.

14.
Lupus ; 21(2): 128-35, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22235042

RESUMO

OBJECTIVE: To investigate the clinical, laboratory and histological manifestations of patients who received illegal injections of foreign substances for cosmetic purposes. PATIENTS AND METHODS: We studied patients who met the following inclusion criteria: 1) history of application of foreign substances for cosmetic purposes, 2) clinical data of autoimmune disease or non-specific autoimmune manifestation (i.e. arthralgias, myalgia, malaise, fever, and weight loss), 3) detection of autoantibodies in patients' sera, 4) histological evidence of chronic inflammation and/or granulomatous reaction to foreign body. RESULTS: Fifty female patients aged 44.4 ± 10 years were studied. The mean time between application of foreign substances and onset of symptoms was 4.5 ± 4.3 years. Patients were followed for 12 ± 7.5 years. Forty-one patients were injected with mineral oil, nine patients received other substances: three iodine gadital, one guayacol, one guayacol plus silicone fluid, two collagen, two silicone fluid. The sites of application were: buttocks (36), legs and/or thighs (11), breasts (eight) hands and face (one), face (two) (seven patients received an injection to more than one site). Thirty patients presented with non-specific autoimmune manifestations, whereas 20 patients fulfilled the criteria for a defined autoimmune disease such as systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis, overlap syndrome, autoimmune hemolytic anemia, autoimmune thyroiditis, autoimmune hepatitis, and ulcerative colitis. CONCLUSIONS: Cases of human adjuvant disease following illegal injections of oil substances for cosmetic purposes are reported. Patients presented with defined autoimmune diseases as well as with non-specific autoimmune manifestations. Illegal injection of these substances could lead to serious local and systemic complications, even to death. These cases represent another model of Autoimmune/inflammatory Syndrome Induced by Adjuvants (ASIA). The use of these substances should be prohibited.


Assuntos
Adjuvantes Farmacêuticos/efeitos adversos , Doenças Autoimunes/induzido quimicamente , Técnicas Cosméticas/efeitos adversos , Corpos Estranhos/imunologia , Adolescente , Adulto , Doenças Autoimunes/imunologia , Doenças Autoimunes/patologia , Doenças Autoimunes/fisiopatologia , Técnicas Cosméticas/ética , Feminino , Humanos , Pessoa de Meia-Idade , Síndrome , Adulto Jovem
15.
Int J Biometeorol ; 56(6): 993-9, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22116633

RESUMO

Heat stress generates a significant economic impact for the dairy industry in arid and semi-arid regions of the world, so that heat abatement is an important issue for dairy producers. The objective of this study was to evaluate effects of two short-term cooling periods on physiological and productive status of lactating Holstein cows during hot ambient temperatures. Thirty-nine multiparous cows were blocked by milk yield and assigned to one of three treatments including: control group (C), cows cooled before milking time (0500 and 1700 h daily, 1 h cooling); AM group, cows cooled at 1000 h and before milking (2 h cooling); and AM + PM group, cows cooled at 1100, 1500 and 2200 h, as well as before milking (4 h cooling). The cooling system was placed in the holding pen which the cows were moved through for cooling. Respiratory rate, and temperatures of thurl and right flank, were lower (P < 0.05) in cows from the AM + PM group than AM and C cows during the morning and afternoon. However, udder temperature was higher in the AM + PM group compared to AM and C groups during the afternoon, although lower than the AM group during the morning. Rectal temperature was similar in all groups. Thyroxin concentrations tended (P < 0.10) to be lower in AM + PM relative to the AM and C groups. The AM + PM group had higher (P < 0.05) milk production than C (18.70 vs. 17.43 kg, respectively), and AM + PM cows had a trend (P < 0.10) to increased milk energy output vs. the C and AM groups (13.75 vs. 13.18 and 13.15 Mcal, respectively). Protein and fat in milk, body condition score, glucose, cholesterol, triglycerides and triiodothyronine were similar among the groups. Four hours of cooling with spray and fans during severe summer temperatures only modestly improved milk yield of lactating Holstein cows.


Assuntos
Bovinos/fisiologia , Resposta ao Choque Térmico/fisiologia , Lactação/fisiologia , Animais , Temperatura Corporal , Clima Desértico , Feminino , Lipídeos/análise , México , Leite/química , Proteínas do Leite/análise , Taxa Respiratória , Estações do Ano , Temperatura , Tiroxina/sangue
16.
J Phys Condens Matter ; 33(40)2021 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-34252896

RESUMO

Ising-like spin-1/2 magnetic materials are of interest for their ready connection to theory, particularly in the context of quantum critical behavior. In this work we report detailed studies of the magnetic properties of a member of the rare earth pyrosilicate family, D-Er2Si2O7, which is known to display a highly anisotropic Ising-likeg-tensor and effective spin-1/2 magnetic moments. We used powder neutron diffraction, powder inelastic neutron spectroscopy (INS), and single crystal AC susceptibility to characterize its magnetic properties. Neutron diffraction enabled us to determine the magnetic structure below the known transition temperature (TN= 1.9 K) in zero field, confirming that the magnetic state is a four-sublattice antiferromagnetic structure with two non-collinear Ising axes, as was previously hypothesized. Our powder INS data revealed a gapped excitation at zero field, consistent with anisotropic (possibly Ising) exchange. An applied field of 1 T produces a mode softening, which is consistent with a field-induced second order phase transition. To assess the relevance of D-Er2Si2O7to the transverse field Ising model, we performed AC susceptibility measurements on a single crystal with the magnetic field oriented in the direction transverse to the Ising axes. This revealed a transition at 2.65 T at 0.1 K, a field significantly higher than the mode-softening field observed by powder INS, showing that the field-induced phase transitions are highly field-direction dependent as expected. These measurements suggest that D-Er2Si2O7may be a candidate for further exploration related to the transverse field Ising model.

17.
Nat Commun ; 12(1): 5331, 2021 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-34504075

RESUMO

An ongoing challenge in the study of quantum materials, is to reveal and explain collective quantum effects in spin systems where interactions between different modes types are important. Here we approach this problem through a combined experimental and theoretical study of interacting transverse and longitudinal modes in an easy-plane quantum magnet near a continuous quantum phase transition. Our inelastic neutron scattering measurements of Ba2FeSi2O7 reveal the emergence, decay, and renormalization of a longitudinal mode throughout the Brillouin zone. The decay of the longitudinal mode is particularly pronounced at the zone center. To account for the many-body effects of the interacting low-energy modes in anisotropic magnets, we generalize the standard spin-wave theory. The measured mode decay and renormalization is reproduced by including all one-loop corrections. The theoretical framework developed here is broadly applicable to quantum magnets with more than one type of low energy mode.

18.
Int J Clin Pract ; 64(5): 594-603, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20456213

RESUMO

AIMS: The aim of this study was to investigate the efficacy and safety of 10 mg vardenafil orodispersible tablet (ODT) vs. placebo in a general population of men with erectile dysfunction (ED). METHODS: This was a double-blind, multicentre, randomised, parallel-group, placebo-controlled study conducted at 35 centres in Australia, Canada, Mexico and the United States. Subjects aged > or =18 years, with ED for at least 6 months, were randomised to receive 12 weeks of on-demand treatment with either 10 mg vardenafil ODT or placebo. Each treatment group was stratified such that approximately half of the subjects were aged > or = 65 years. Primary efficacy variables were the erectile function domain of the International Index of Erectile Function (IIEF-EF) and Sexual Encounter Profile questions 2 (SEP2) and 3 (SEP3). Secondary variables included SEP diary questions 1, 4, 5 and 6, the patient version of the Treatment Satisfaction Scale (TSS) and the Global Assessment Question (GAQ). RESULTS: Of the 473 men enrolled in the study (51.4% aged > or =65 years), 331 were included in the intent-to-treat population (vardenafil ODT, n = 169; placebo, n = 162). Vardenafil ODT therapy was statistically significantly superior to placebo for all primary (i.e. IIEF-EF, SEP2, SEP3) and secondary efficacy variables (p < 0.0001). Treatment-emergent adverse events were mostly mild to moderate in severity, and comparable in both incidence and type with those of the film-coated tablet formulation. CONCLUSIONS: Treatment with 10 mg vardenafil ODT, taken on demand, significantly improved erectile function and was effective and well tolerated in a broad population of men with ED.


Assuntos
Disfunção Erétil/tratamento farmacológico , Imidazóis/administração & dosagem , Inibidores de Fosfodiesterase/administração & dosagem , Piperazinas/administração & dosagem , Administração Oral , Adulto , Idoso , Método Duplo-Cego , Humanos , Imidazóis/efeitos adversos , Masculino , Pessoa de Meia-Idade , Inibidores de Fosfodiesterase/efeitos adversos , Piperazinas/efeitos adversos , Sulfonas/administração & dosagem , Sulfonas/efeitos adversos , Comprimidos , Resultado do Tratamento , Triazinas/administração & dosagem , Triazinas/efeitos adversos , Dicloridrato de Vardenafila
19.
Phys Rev B ; 1012020.
Artigo em Inglês | MEDLINE | ID: mdl-33655091

RESUMO

We report a comprehensive neutron scattering study of low energy magnetic excitations in the breathing pyrochlore helimagnetic Cu2OSeO3. Fully documenting the four lowest energy magnetic modes that leave the ferrimagnetic configuration of the "strong tetrahedra" intact ( | ℏ ω | < 13 meV), we find gapless quadratic dispersion at the point for energies above 0.2 meV, two doublets separated by 1.6(2) meV at the R point, and a bounded continuum at the X point. Our constrained rigid spin cluster model relates these features to Dzyaloshinskii-Moriya (DM) interactions and the incommensurate helical ground state. Combining conventional spin wave theory with a spin cluster form factor accurately reproduces the measured equal time structure factor through multiple Brillouin zones. An effective spin Hamiltonian describing complex anisotropic intercluster interactions is obtained.

20.
Nat Commun ; 11(1): 6003, 2020 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-33243978

RESUMO

Nickelates are a rich class of materials, ranging from insulating magnets to superconductors. But for stoichiometric materials, insulating behavior is the norm, as for most late transition metal oxides. Notable exceptions are the 3D perovskite LaNiO3, an unconventional paramagnetic metal, and the layered Ruddlesden-Popper phases R4Ni3O10, (R = La, Pr, Nd). The latter are particularly intriguing because they exhibit an unusual metal-to-metal transition. Here, we demonstrate that this transition results from an incommensurate density wave with both charge and magnetic character that lies closer in its behavior to the metallic density wave seen in chromium metal than the insulating stripes typically found in single-layer nickelates like La2-xSrxNiO4. We identify these intertwined density waves as being Fermi surface-driven, revealing a novel ordering mechanism in this nickelate that reflects a coupling among charge, spin, and lattice degrees of freedom that differs not only from the single-layer materials, but from the 3D perovskites as well.

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