Observation of electromagnetically induced transparency for a squeezed vacuum with the time domain method.

A probe light in a squeezed vacuum state was injected into cold 87Rb atoms with an intense control light in a coherent state. A sub-MHz window was created due to electromagnetically induced transparency, and the incident squeezed vacuum could pass through the cold atoms without optical loss, as was successfully monitored using a time-domain homodyne method.

Antiholons in one-dimensional t-J models.

Using a newly developed hybrid Monte Carlo algorithm for the nearest-neighbor (nn) t-J model, we show that antiholons identified in the supersymmetric inverse squared (IS) t-J model are clearly visible in the electron-addition spectrum of the nn t-J model at J=2t and also for J=0.5t, a value of experimental relevance.

Ca2+-dependent contractility of isolated and demembranated macronuclei in the hypotrichous ciliate Euplotes aediculatus.

The hypotrichous ciliated protozoan Euplotes aediculatus possesses a characteristic C-shaped somatic nucleus (macronucleus) within the cytoplasm, which shows dynamic shape change during the cell cycle. It is shown that isolated macronuclei possess Ca(2+)-dependent contractility. Macronuclei were isolated, stuck fast on the glass surface, and subjected to different concentrations of Ca(2+) in a Ca(2+)-EGTA buffer. The nuclei became expanded at [Ca(2+)]<10(-7)M, and they contracted on subsequent addition of higher concentrations of Ca(2+). Cycles of expansion and contraction of the nucleus could be repeated many times by alternate addition of EGTA and Ca(2+), indicating that the size of isolated nuclei can be regulated by [Ca(2+)] alone. The nuclear contraction was observed in all phases of the cell cycle, but contractility was less evident around replication bands in the S phase. In addition to the hypotrichous ciliate Euplotes, similar Ca(2+)-dependent nuclear contractility was found to exist in other cell types, including protozoans of different taxa (a heliozoon Actinophrys sol and a peniculine ciliate Paramecium bursaria), and also mammalian culture cells (HeLa cells). Our findings suggest a possibility that Ca(2+)-dependent nuclear contractility may be shared among diverse eukaryotic organisms.

Single oral dose of geranylgeranylacetone induces heat-shock protein 72 and renders protection against ischemia/reperfusion injury in rat heart.

BACKGROUND: Induction of heat-shock proteins (HSPs) results in cardioprotection against ischemic insult. Geranylgeranylacetone (GGA), known as an antiulcer agent, reportedly induces HSP72 in the gastric mucosa and small intestine of rats. The present study tested the hypothesis that oral GGA would induce HSP72 in the heart and thus render cardioprotection against ischemia/reperfusion injury in rats. METHODS AND RESULTS: Cardiac expression of HSPs was quantitatively evaluated in rats by Western blot analysis. Ten minutes of whole-body hyperthermia induced HSP72 expression in the rat hearts. A single oral dose of GGA (200 mg/kg) also induced expression of HSP72, which peaked at 24 hours after administration. Therefore, isolated perfused heart experiments using a Langendorff apparatus were performed 24 hours after administration of 200 mg/kg GGA (GGA group) or vehicle (control group). After a 5-minute stabilization period, no-flow global ischemia was given for 20, 40, or 60 minutes, followed by 30 minutes of reperfusion. During reperfusion, the functional recovery was greater and the released creatine kinase was less in the GGA group than in the control group. Electron microscopy findings revealed that the ischemia/reperfusion-induced damage of myocardial cells was prevented in GGA-treated myocytes. CONCLUSIONS: The results suggest that oral GGA is cardioprotective against ischemic insult through its induction of HSP72.

Electron addition spectrum in the supersymmetric t-J model with inverse-square interaction.

The electron addition spectrum A+(k,omega) is obtained analytically for the one-dimensional (1D) supersymmetric t-J model with 1/r2 interaction. The result is obtained first for a small-sized system and its validity is checked against the numerical calculation. Then the general expression is found which is valid for arbitrary size of the system. The thermodynamic limit of A+(k,omega) has a simple analytic form with contributions from one spinon, one holon, and one antiholon-all of which obey fractional statistics. The upper edge of A+(k,omega) in the (k,omega) plane includes a delta-function peak which reduces to that of the single-electron band in the low-density limit.

Exact dynamical structure factor of the degenerate haldane-shastry model

The dynamical structure factor S(q,omega) of the K-component ( K = 2, 3, 4) spin chain with a 1/r(2) interaction is derived exactly at zero temperature for the arbitrary size of the system. The result is interpreted in terms of a free quasiparticle picture which is a generalization of the spinon picture in the SU(2) case. The excited states consist of K quasiparticles each of which is characterized by a set of K-1 quantum numbers. Divergent singularities of S(q,omega) at the spectral edges are derived analytically. The analytic result is checked numerically for finite systems.

Radiofrequency catheter ablation from the left sinus of Valsalva in a patient with idiopathic ventricular tachycardia.

We report the case of a 54-year-old woman with idiopathic VT originating in the left ventricular outflow tract. She initially presented with palpitations and light-headedness. The morphology of the PVCs exhibited an inferior axis and tall R waves were noted in all the precordial leads. Spontaneous PVCs were transiently terminated by an intravenous injection of adenosine triphosphate. Radiofrequency catheter ablation from the left sinus of Valsalva successfully abolished the PVCs and the VT.

Novel mutation of the DAX1 gene in a patient with X-linked adrenal hypoplasia congenita and hypogonadotropic hypogonadism.

X-linked adrenal hypoplasia congenita (AHC) is characterized by primary adrenal insufficiency and is frequently associated with hypogonadotropic hypogonadism (HHG). Mutations of the DAX1 gene have been reported in patients with AHC and HHG. We found a novel DAX1 mutation in our patient. Sequence analysis of the patient's DAX1 demonstrated a 1-bp (G) deletion at codon 49 in exon 1. The mutation shifts the reading frame, resulting in completely different amino acid sequences from codon 49 to the premature stop codon at 84. The G was present at this position in the sequences of the father and 2 younger brothers. Direct sequence and single-strand conformation polymorphism analyses of polymerase chain reaction fragments revealed that the mutation at codon 49 was heterozygously present in the mother's DAX1 gene. The codon 84 is located in the first half of the DNA binding domain, and the mutation site is closer to the N-terminus than those in previously reported cases. The onset of adrenal insufficiency in the neonatal period as seen in our patient has also been reported in other patients with different DAX1 mutations, especially in a patient with DAX1 protein lacking 11 amino acids at the C-terminus. Therefore, it is less likely that position of termination codons correlate to clinical manifestations.