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Cervical nodal metastasis is a key prognostic factor in patients with papillary thyroid carcinoma. The role of lymph nodes in papillary thyroid carcinoma management and prognosis remains controversial.
Level IIb lymph nodes obtained from 44 patients with papillary thyroid carcinoma were histopathologically examined retrospectively. Specimens were classified as ipsilateral or contralateral. The number of dissected nodes and prevalence of level IIb metastasis were compared according to pre-operative clinical nodal stage.
In the node-negative neck, the prevalence of contralateral and ipsilateral IIb nodes was 0 out of 20 and 0 out of 3, respectively. In the node-positive neck, the prevalence of contralateral and ipsilateral IIb nodes was 1 out of 13 (7.70 per cent) and 3 out of 41 (7.32 per cent), respectively. Clinically determined and pathologically confirmed level IIb node negativity were significantly associated. Thirty-four patients (77.3 per cent) developed accessory nerve complications from level IIb dissection.
Level IIb neck dissection for papillary thyroid carcinoma may be required if pre-operative examination reveals multilevel, level IIa or suspicious level IIb metastasis.
The costs and benefits of polyandry are still not well understood. We studied the effects of multiple mating on the reproductive performance of female Brontispa longissima (Coleoptera: Chrysomelidae), one of the most serious pests of the coconut palm, by using three experimental treatments: (1) singly-mated females (single treatment); (2) females that mated 10 times with the same male (repetition treatment); and (3) females that mated once with each of 10 different males (polyandry treatment). Both multiple mating treatments resulted in significantly greater total egg production and the proportion of eggs that successfully hatched (hatching success) than with the single mating treatment. Furthermore, the polyandry treatment resulted in greater total egg production and hatching success than with the repetition treatment. Thus, mate diversity may affect the direct and indirect benefits of multiple mating. Female longevity, the length of the preoviposition period, the length of the period from emergence to termination of oviposition, and the length of the ovipositing period did not differ among treatments. The pronounced fecundity and fertility benefits that females gain from multiple mating, coupled with a lack of longevity costs, apparently explain the extreme polyandry in B. longissima.
The females of the white grub beetle, Dasylepida ishigakiensis, release two enantiomers of 2-butanol, (R)-2-butanol and (S)-2-butanol. The ratio describing the relative proportions of these two enantiomers (R/S ratio) has not yet been investigated. (R)-2-Butanol has been shown to attract males in laboratory and field experiments, whereas (S)-2-butanol tends to inhibit them. To determine the R/S ratio of the 2-butanol emitted by virgin females, we collected 2-butanol from young (53 days old), mature (63 days old) and old females (73 days old) using water, extracted with an SPME fibre and subsequently injected into GC-MS. The major component of the 2-butanol emitted by the young females was (R)-2-butanol, but as the females aged, the component ratio favoured (S)-2-butanol. Young females released an 80:20 mixture of (R)- and (S)-2-butanol, whereas old females released a 45:55 mixture. The EAG response of male antennae to a 50:50 ratio (racemic mixture) showed a similar dose-response curve to that of (R)-2-butanol. The male orientation responses to (R)-2-butanol decreased when the relative proportion of (S)-2-butanol increased. An inhibitory and/or masking effect of (S)-2-butanol on male orientation behaviour was also observed in the flight tunnel assay. These results suggest that males are more strongly attracted to young females than to old females. We also discuss the possibility of using 2-butanol isomers as a control or monitoring agent for this insect.
A serious sugarcane pest, Dasylepida ishigakiensis, remains in the soil during most of its life cycle except for a short period for mating. Mating disruption by an artificial release of the sex pheromone (R)-2-butanol (R2B), therefore, may be a feasible method to control this pest. We examined the effects of artificial release of R2B and its related compounds, (S)-2-butanol (S2B) and the racemic 2-butanol (rac-2B), on the mating success of this beetle both in the laboratory and in the field. In flight tunnel experiments, almost all males orientated towards a R2B-releasing source and 40% of them landed on the source. When the atmosphere was permeated with R2B, the frequency of males landing on the model was significantly reduced. Both rac-2B and S2B were less effective, but substantial reduction in landing success by males was achieved at higher rac-2B concentrations. R2B released from polyethylene dispensers in sugarcane plots greatly reduced not only the proportion of females mated with males but also the number of males caught by R2B-baited traps, indicating that male mate-searching behaviour was strongly affected by the released R2B. Similar inhibitory effects on male behaviour were also observed when tube- or rope-type dispensers released high rac-2B concentrations in the field. These results indicate that it would be highly possible to control D. ishigakiensis through the disruption of the sexual communication by releasing either synthetic R2B or rac-2B.
We present the results of a mm wavelength methanol maser survey towards massive star forming regions. We have carried out Class II methanol maser observations at 86.6 GHz, 86.9 GHz and 107.0 GHz, simultaneously, using the Nobeyama 45 m telescope. We selected 108 6.7 GHz methanol maser sources with declinations above −25 degrees and fluxes above 20 Jy. The detection limit of maser observations was ~3 Jy. Of the 93 sources surveyed so far, we detected methanol emission in 25 sources (27%) and “maser” emission in nine sources (10%), of which thre “maser” sources are new detections. The detection rate for maser emission is about half that of a survey of the southern sky (Caswell et al. 2000). There is a correlation between the maser flux of 107 GHz and 6.7 GHz/12 GHz emission, but no correlation with the “thermal” (non maser) emission. From results of other molecular line observations, we found that the sources with methanol emission show higher gas temperatures and twice the detection rate of SiO emission. This may suggest that dust evaporation and destruction by shock are responsible for the high abundance of methanol molecules, one of the required physical conditions for maser emission.
The flow-visualization methods of dye injection, hydrogen-bubble generation and paraffin mist are employed to investigate radial flow between parallel circular disks with a steady influx. Three distinct flow patterns are observed in the range of Re between 1.5 and 50. (1) Steady flow without boundary-layer separation and re-attachment, for Re < Rec. (2) A self-controlled flow oscillation which decays further downstream, in the range of Rec [les ] Re < Ret. (3) A self-sustained flow fluctuation which develops into a laminar-turbulent transition with a reverse transition further downstream, when Re [ges ] Ret. Rec and Ret are the critical and transition Reynolds number, respectively.
The oscillating flows are caused by a vortex street consisting of vortices (i.e. separating annular bubbles) that separate periodically and alternately from both disks. Finite-difference solutions of the unsteady vorticity transport equation broadly agree with certain experimental observations. The study concludes that the separation and reattachment of shear layers in the radial flow through parallel disks are unsteady phenomena and the sequence of nucleation, growth, migration and decay of the vortices is self-sustained.
The aim of this study was to characterise the arrhythmogenic mechanisms involved in hypokalaemia-induced sustained ventricular fibrillation (SVF), in hypertensive rats. The hearts from rats with hypertension induced by the nitric oxide synthase inhibitor L-NAME, and age-matched normotensive controls, were perfused in Langendorff mode with oxygenated Krebs-Henseleit solution followed by a K+-deficient solution. In additional experiments, free intracellular Ca2+ concentration ([Ca2+]i) was measured using fura-2 in conjunction with an epicardial optical probe. The epicardial electrocardiogram was continuously monitored during all experiments. The gap junction protein connexin-43 and the ultrastructure of the cardiomyocytes were examined, and selected enzyme activities were measured in situ. There was a higher incidence of low-K+-induced SVF in the hearts of hypertensive compared to normotensive rats (83 % vs. 33 %, P < 0.05). Perfusion with a low-K+-containing solution lead to elevation of diastolic [Ca2+]i that was accompanied by premature beats, bigeminy, ventricular tachycardia and transient ventricular fibrillation. These events occurred earlier with increased incidence and duration in the hearts of hypertensive rats (arrhythmia scores: hypertensive, 4.9 ± 0.7; normotensive, 3.1 ± 0.1; P < 0.05), which exhibited apparent remodelling accompanied by a significant decrease in the density of connexin-43-positive gap junctions. Moreover, low-K+-related myocardial changes, including local impairment of intermyocyte junctions, ultrastructural alterations due to Ca2+ overload and intercellular uncoupling, and decreased enzyme activities were more pronounced and more dispersed in hypertensive than normotensive rats. In conclusion, nitric oxide-deficient hypertension is associated with decreased myocardial coupling at gap junctions. The further localised deterioration of junctional coupling, due to low-K+-induced Ca2+ disturbances, as well as spatial heterogeneity of myocardial alterations including interstitial fibrosis, probably provide the mechanisms for re-entry and sustaining ventricular fibrillation. Experimental Physiology (2002) 87.2, 195-205.
Lowering the fabrication temperature for ferroelectric films is very important not only for silicon monolithic circuits but also for various substrates. Amorphous PbTiO3 thin films were prepared on glass substrates using ArF pulsed laser deposition (PLD). They were subsequently treated by a laser-induced phase transformation technique to achieve a perovskite structure. After irradiation by an ArF pulsed laser with an energy density 50mJ/cm2 in air, the films crystallized into the perovskite structure. It was possible to maintain the substrate at room temperature during the whole fabrication process. The structure, morphology and composition of the films were characterized by X-ray diffraction diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), respectively. The surface of film irradiated with a laser was often rather rough and peeled off everywhere. It was necessary to control the number of laser pulses to avoid damaging the films. The effects of chemical composition and fabrication temperature are also discussed.
The radioactive isotopes, such as 44Ti and 56Ni, are synthesized as a result of rapid nucleosynthesis in supernova explosions. The gamma-ray photons coming out from the decay sequence of 44Ti is now a strong candidate to explain the the late light curve of SN 1987A. It is noted here that the energy release from the 44Ti decay depends strongly on its half-life. However, the published values for 44Ti half-life display a large spread, ranging from ~ 35 to ~ 68 years. In this paper (Kumagai et al. 1997; see also Kumagai et al. 1993), we discuss the value of the half-life by comparing the theoretical light curves and the observations in SN 1987A. The unestablished half-life value is related to the ratio of the abundance of 44Ti to that of 56Ni.
Electrically detected magnetic resonance (EDMR) has been used to study carrier recombination in GaAs/AlGaAs quantum well structures grown by molecular beam epitaxy. The spin dependent photoconductivity signals depend strongly on the electrical contact properties. Using silver paste contacts a narrow (18 G) resonance located at g = 2.001 is observed. It has been previously attributed to surface defects on GaAs. Using alloyed In-contacts other signals are detected. The dominant resonance observed at 9 GHz has an isotropic g-value of g = 1.99 with a halfwidth of 200 G and is therefore assigned to Cr4+. Other signals of considerably lower intensity are explained by the well known electron paramagnetic resonance (EPR) properties of the Gai-interstitial and the AsGa-antisite defects. EDMR performed at 34 GHz allows the experimental separation of the two sets of hyperfine lines.
We investigated the reason of the (imbalanced) accumulation of electrons in AIGaSb/lnAs/AIGaSb QW system in spite of the p-type conduction of undoped AIGaSb. It was found that the concentration of the accumulated electrons negligibly depended on the number of the interfaces, but increased linearly with the effective AlSb thickness. These results indicate that donor levels in AIGaSb are the dominant electron sources. We propose a model that the deep acceptors with larger concentration and donors coexist, and the electron accumulation depends on the energy position of the acceptor in AIGaSb with respect to the quantum level in the InAs well. Acceptor levels obtained experimentally are about 100 meV higher than the bottom of the InAs conduction band, and we succeeded in eliminating the electron accumulation by making the quantum level of the InAs well higher than this acceptor level. The origins of the donors and acceptors are also discussed.
The wavelength scalings of soft X-ray and hot electron generation efficiencies were studied using 1·05, 0·53, 0·35 and 0·26 μm lasers. A coupling efficiency from absorbed laser energy to compressed fuel core of 4.5% was obtained by using the GEKKO XII green laser.
For an integer n ≥ 2, we consider the following three groups:
GLn-1(R), the group of invertible (n - 1) × (n - 1) matrices with entries in R = ℤ [x1, …,xm] or K[x1, …,xm+1], m ≥ 1, the polynomial ring over the integers ≥ or a field K.
Aut(M(n)), the group of automorphisms of the free metabelian groups M(n) = F(n)/F″(n) of rank n where F(n) is the free group of rank n and F″(n) its second derived group.
AutK(P(n)), the group of K-automorphisms of the polynomial ring P(n) = K[x1,…,xn] in n indeterminates over the field K.
AutK(P(n)), the group of K-automorphisms of the polynomial ring P(n) = K[x1,…,xn] in n indeterminates over the field K.
A study of these groups has split into three distinct phases corresponding to values n = 2, n = 3 and n ≥ 4. Our theme is that the three groups have many similar or analogous characteristics and should be considered as one and the same study.
Consider for example an immediate question confronting one in a study of these groups. What is a reasonable set of generators? More specifically, do any of these groups possess elements other than the obvious or tame ones? (See §2 for definitions). Apart from the case n = 3, evidence is pointing to the fact that these groups possess only tame elements. The exceptional case n = 3 is indeed very different from the cases n ≠ 3, as we shall see, but apparently similar for all three groups. We attempt to justify this apparent similarity in our explanations below.