Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 18 de 18
Filtrar
Mais filtros












Base de dados
Intervalo de ano de publicação
1.
Phys Rev Lett ; 133(7): 071803, 2024 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-39213579

RESUMO

We report on a search for magnetic monopoles (MMs) produced in ultraperipheral Pb-Pb collisions during Run 1 of the LHC. The beam pipe surrounding the interaction region of the CMS experiment was exposed to 184.07 µb^{-1} of Pb-Pb collisions at 2.76 TeV center-of-mass energy per collision in December 2011, before being removed in 2013. It was scanned by the MoEDAL experiment using a SQUID magnetometer to search for trapped MMs. No MM signal was observed. The two distinctive features of this search are the use of a trapping volume very close to the collision point and ultrahigh magnetic fields generated during the heavy-ion run that could produce MMs via the Schwinger effect. These two advantages allowed setting the first reliable, world-leading mass limits on MMs with high magnetic charge. In particular, the established limits are the strongest available in the range between 2 and 45 Dirac units, excluding MMs with masses of up to 80 GeV at a 95% confidence level.

2.
Phys Rev Lett ; 132(8): 083402, 2024 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-38457696

RESUMO

We report on laser cooling of a large fraction of positronium (Ps) in free flight by strongly saturating the 1^{3}S-2^{3}P transition with a broadband, long-pulsed 243 nm alexandrite laser. The ground state Ps cloud is produced in a magnetic and electric field-free environment. We observe two different laser-induced effects. The first effect is an increase in the number of atoms in the ground state after the time Ps has spent in the long-lived 2^{3}P states. The second effect is one-dimensional Doppler cooling of Ps, reducing the cloud's temperature from 380(20) to 170(20) K. We demonstrate a 58(9)% increase in the fraction of Ps atoms with v_{1D}<3.7×10^{4} ms^{-1}.

3.
Nature ; 602(7895): 63-67, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-35110756

RESUMO

Electrically charged particles can be created by the decay of strong enough electric fields, a phenomenon known as the Schwinger mechanism1. By electromagnetic duality, a sufficiently strong magnetic field would similarly produce magnetic monopoles, if they exist2. Magnetic monopoles are hypothetical fundamental particles that are predicted by several theories beyond the standard model3-7 but have never been experimentally detected. Searching for the existence of magnetic monopoles via the Schwinger mechanism has not yet been attempted, but it is advantageous, owing to the possibility of calculating its rate through semi-classical techniques without perturbation theory, as well as that the production of the magnetic monopoles should be enhanced by their finite size8,9 and strong coupling to photons2,10. Here we present a search for magnetic monopole production by the Schwinger mechanism in Pb-Pb heavy ion collisions at the Large Hadron Collider, producing the strongest known magnetic fields in the current Universe11. It was conducted by the MoEDAL experiment, whose trapping detectors were exposed to 0.235 per nanobarn, or approximately 1.8 × 109, of Pb-Pb collisions with 5.02-teraelectronvolt center-of-mass energy per collision in November 2018. A superconducting quantum interference device (SQUID) magnetometer scanned the trapping detectors of MoEDAL for the presence of magnetic charge, which would induce a persistent current in the SQUID. Magnetic monopoles with integer Dirac charges of 1, 2 and 3 and masses up to 75 gigaelectronvolts per speed of light squared were excluded by the analysis at the 95% confidence level. This provides a lower mass limit for finite-size magnetic monopoles from a collider search and greatly extends previous mass bounds.

4.
Phys Rev Lett ; 126(7): 071801, 2021 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-33666471

RESUMO

The MoEDAL trapping detector consists of approximately 800 kg of aluminum volumes. It was exposed during run 2 of the LHC program to 6.46 fb^{-1} of 13 TeV proton-proton collisions at the LHCb interaction point. Evidence for dyons (particles with electric and magnetic charge) captured in the trapping detector was sought by passing the aluminum volumes comprising the detector through a superconducting quantum interference device (SQUID) magnetometer. The presence of a trapped dyon would be signaled by a persistent current induced in the SQUID magnetometer. On the basis of a Drell-Yan production model, we exclude dyons with a magnetic charge ranging up to five Dirac charges (5g_{D}) and an electric charge up to 200 times the fundamental electric charge for mass limits in the range 870-3120 GeV and also monopoles with magnetic charge up to and including 5g_{D} with mass limits in the range 870-2040 GeV.

5.
Rhinology ; 36(3): 98-100, 1998 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-9830671

RESUMO

Thirty-three subjects with chronic rhinitis used nicotine nasal spray in an open study as an aid in smoking cessation. Thirty-eight percent of them were completely abstinent at 12 weeks, whereas 35% were completely abstinent at 20 weeks. The nasal spray was associated with irritant nasal side effects, which occurred most often in the early stages of treatment. Clinical nasal examinations could not observe any significant impairment in nasal conditions following spray use. In conclusion, this study confirms the short-term safety of the nicotine nasal spray as an aid in smoking cessation.


Assuntos
Nicotina/efeitos adversos , Agonistas Nicotínicos/efeitos adversos , Rinite/fisiopatologia , Abandono do Hábito de Fumar/métodos , Administração Intranasal , Adulto , Aerossóis , Idoso , Núcleo Celular/ultraestrutura , Doença Crônica , Cílios/ultraestrutura , Citoplasma/ultraestrutura , Células Epiteliais/patologia , Estudos de Avaliação como Assunto , Feminino , Seguimentos , Células Caliciformes/patologia , Humanos , Irritantes/efeitos adversos , Masculino , Pessoa de Meia-Idade , Mucosa Nasal/efeitos dos fármacos , Mucosa Nasal/patologia , Nicotina/administração & dosagem , Agonistas Nicotínicos/administração & dosagem , Nariz/patologia , Nariz/fisiopatologia , Pico do Fluxo Expiratório/fisiologia , Segurança , Olfato/fisiologia , Fumar/patologia , Fumar/fisiopatologia , Prevenção do Hábito de Fumar
6.
J Laryngol Otol ; 111(4): 337-9, 1997 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9176614

RESUMO

A relationship between the reactivity of the nasal mucosa and changes in female sex hormones have been debated for a long time, although no evidence has been presented to prove or disprove this relationship. Nasal patency was therefore measured by nasal expiratory peak-flow in 26 women for two months in order to study changes in nasal mucosal congestion during the menstrual cycle. In another eight women, nasal congestion was measured by acoustic rhinometry, and symptoms of nasal stuffiness were registered during periods when there were various levels of plasma oestradiol and progesterone. Finally, nasal mucosal biopsies were taken for preparation of receptors for oestradiol and progesterone. This study could not verify the effects of female sex hormones on the nasal mucosa. This could be explained by the fact that no receptors for oestradiol and progesterone were found.


Assuntos
Menstruação/fisiologia , Mucosa Nasal/irrigação sanguínea , Adolescente , Adulto , Feminino , Humanos , Pessoa de Meia-Idade , Mucosa Nasal/química , Receptores de Superfície Celular/análise , Receptores de Estrogênio/análise , Receptores de Progesterona/análise
7.
Oncol Rep ; 4(3): 515-6, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-21590088

RESUMO

The cytogenetical observations in a mucoepidermoid carcinoma (MEG) arising from heterotopic intranodal salivary gland tissue are presented. The MEC was characterized by two reciprocal translocations, viz, t(1;7) (p36;q11) and t(11;19) (q14-21;p11). The present and the previous studies show that the last rearrangement or related deviations characterize about 40% of all MEG. The remaining cases form a subgroup distinguished by trisomies with or without concomitant structural deviations other than those affecting 11q14-22. At least MEC of the first subgroup show neither predilection for any specific anatomical site nor for any age group or particular sex. Inducing agent(s) and genotypic status of the tissue of origin seem to be the decisive factors for the chromosomal patterns in MEG.

8.
APMIS ; 102(3): 236-40, 1994 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8185891

RESUMO

Positive staining for estrogen receptors is reported in a new case of aggressive angiomyxoma of the vulva. Clinical, light- and electron microscopic features as well as immunohistochemical reactions in this case are compared with the 28 earlier published cases, and the main differential diagnosis, angiomyofibroblastoma of the vulva, is discussed.


Assuntos
Mixoma/patologia , Recidiva Local de Neoplasia , Receptores de Estrogênio/análise , Neoplasias Vulvares/patologia , Feminino , Humanos , Imuno-Histoquímica , Microscopia Eletrônica , Pessoa de Meia-Idade , Mixoma/cirurgia , Mixoma/ultraestrutura , Receptores de Estrogênio/biossíntese , Neoplasias Vulvares/cirurgia , Neoplasias Vulvares/ultraestrutura
9.
Cancer Genet Cytogenet ; 58(1): 14-7, 1992 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-1728944

RESUMO

The chromosomes of a human benign chondroblastoma of the jaw were studied by in vitro technique. Approximately one-third of the analyzed cells had a normal karyotype. The remaining two-thirds constituted an abnormal monoclonal population with a complex and balanced translocation. The observations are different from those in previously studied benign primary bone tumors. The breakpoint in 22q, however, is similar or very close to that observed in two extraskeletal myxoid chondrosarcomas earlier reported.


Assuntos
Condroblastoma/genética , Neoplasias Maxilomandibulares/genética , Translocação Genética/genética , Adolescente , Cromossomos Humanos Par 13 , Cromossomos Humanos Par 2 , Cromossomos Humanos Par 5 , Feminino , Humanos , Cariotipagem , Células Tumorais Cultivadas
10.
West J Med ; 155(6): 610-2, 1991 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-1812630

RESUMO

Five patients with human immunodeficiency virus (HIV)-related immune thrombocytopenia who were undergoing dental extraction were treated with intravenous immune globulin (IVIG). All patients received IVIG, 1 gram per kg, the day before the dental extraction and again the day of the dental extraction. Four patients had a previous history of minor clinical bleeding. The median baseline platelet count before extraction was 20 X 10(9) per liter (range 13 to 44). The median peak platelet count was 100 X 10(9) per liter (range 56 to 528) following infusion. This peak response was achieved by day 2 in 3 patients and by days 5 and 7 in 1 patient each. No patients had complications or toxicity from the infusions or perioperative bleeding. No patients required blood product transfusions for the surgical procedure. In conclusion, IVIG infusion should be considered in patients with HIV-related immune thrombocytopenia requiring surgical procedures when a prompt rise in platelet count is desired.


Assuntos
Síndrome da Imunodeficiência Adquirida/complicações , Imunoglobulinas Intravenosas/uso terapêutico , Trombocitopenia/terapia , Extração Dentária , Síndrome da Imunodeficiência Adquirida/sangue , Adulto , Humanos , Masculino , Contagem de Plaquetas , Trombocitopenia/complicações , Trombocitopenia/imunologia
12.
Acta Physiol Scand ; 139(1): 39-46, 1990 May.
Artigo em Inglês | MEDLINE | ID: mdl-2356757

RESUMO

Survival and renal function were studied after 60 min of renal ischaemia and contralateral nephrectomy in four groups of French loop rabbits. One group served as untreated control animals. The other groups were pretreated with superoxide dismutase (SOD) and catalase, lidoflazine or a buffered albumin solution containing mannitol, L-methionine and MgCl2. Six out of nine rabbits died during the 14-day follow-up period in the untreated control group, while the corresponding figure in each of the three treatment groups was one out of nine. Five of the rabbits that died exhibited azotaemia or hyperpotassaemia that could explain the death, while four died of non-renal related causes. In the surviving animals, no differences in serum creatinine, potassium and sodium concentration or urinary output of osmoles was observed between the four groups. The increase in serum creatinine of the French loop rabbits observed after 60 min of ischaemia was considerably less pronounced than the corresponding increase observed in New Zealand White rabbits, indicating that the kidneys of the former strain are more tolerant to ischaemia. A cardiomyodepressant factor could be demonstrated in the venous effluent from previously ischaemic kidneys. This release could not be prevented by pretreatment with SOD and catalase.


Assuntos
Isquemia/fisiopatologia , Rim/irrigação sanguínea , Lidoflazina/farmacologia , Oxigênio/antagonistas & inibidores , Piperazinas/farmacologia , Reperfusão , Animais , Creatinina/sangue , Feminino , Radicais Livres , Isquemia/sangue , Isquemia/urina , Rim/patologia , Rim/fisiopatologia , Masculino , Nefrectomia/métodos , Músculos Papilares/fisiopatologia , Potássio/sangue , Coelhos
14.
HNO ; 32(6): 252-4, 1984 Jun.
Artigo em Alemão | MEDLINE | ID: mdl-6469727

RESUMO

A Castleman's tumour of the larynx originating from the left aryepiglottic fold of a 74 year old woman is described. The tumour was radically removed via a lateral pharyngotomy.


Assuntos
Laringe/patologia , Idoso , Feminino , Humanos , Hiperplasia/cirurgia , Faringectomia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...