Intensity discrimination for precedence effect stimuli

When two identical stimuli are presented from two loudspeakers with a brief delay between them, a single image is heard near the source of the leading sound. The delayed sound or echo appears to be suppressed whereas the preceding sound determines perceived location, hence the name, the precedence effect. This study investigated normal-hearing listeners' sensitivity to changes in the intensity of the lagging sound. Pairs of 2-ms white noise bursts, with a 2-ms delay between the onsets of lead and lag, were presented from two loudspeakers 45 degrees left and right of midline in an anechoic chamber. A 2AFC procedure was used to test discrimination of intensity changes in the lead, lag, and both sounds together. The untreated results showed discrimination to be poorest for changes in the lag stimulus. However, when the intensity differences were transformed into predictions of equivalent monaural level based on KEMAR measurements and binaural loudness summation, discrimination for the lag was equal to the other two conditions. A follow-up experiment found that listeners were highly sensitive to the presence of the lag, more sensitive than would be predicted from loudness changes. It is concluded that the precedence effect does not consist of a general suppression or attenuation of the lagging sound, but rather that suppression may be limited to directionality cues.     

Optimized dairy grazing systems in the northeast United States and New Zealand. II. System analysis.

Factors that optimize milk production from Northeast United States and New Zealand grazing systems are compared using a linear programming model. The objective function maximized gross margin per hectare of land farmed. The experimental design compared the optimum characteristics of each system over a range of milk prices. The Northeast has a shorter grazing season and lower cropping costs than New Zealand. The optimum pasture area was 49% of the farm for Northeast systems. Gross margins declined rapidly above 55% or below 36% pasture area. The optimum stocking rate was 1.13 cows/ha, or 2.3 cows/ha of pasture. Optimum per cow production was higher for Northeast [7105 kg of fat-corrected milk (FCM)] than New Zealand (5710 kg of FCM) systems. This was related to lower grain relative to milk prices in the Northeast. New Zealand, all-pasture systems gave the lowest cost per unit of milk but also gave the lowest gross margin across all milk price scenarios. The best use of purchased feed in New Zealand systems was to support increased stocking rate rather than per cow production. Optimum grazing management practices were similar for supplemented New Zealand and Northeast systems. All-pasture New Zealand systems are characterized by short lactations and long autumn rotations to transfer pasture in situ for winter feeding. Higher costs per unit of milk produced will be an inevitable consequence of maximizing gross margin at high milk prices in New Zealand systems.     

What is negative refraction?

We review various published definitions associated with the phenomenon of negative phase velocity propagation of electromagnetic waves in meta-media, as observed through negative refraction. For the principal definition, based on the Poynting vector and the wave vector having negative scalar product, we summarise the various material constraints that have been derived. The distinction between criteria based on the Poynting vector and the group velocity are considered, both in respect of causality, and in the context of moving media. Instances where a fully covariant definition is necessary are also identified, and compared with other results from the extant literature. Satisfaction of the NPV propagation criterion is also considered for surface plasmons.     

A nickel-complex sensitiser for dye-sensitised solar cells

We report the first example of a Ni(II) complex that demonstrates sensitiser function in a Dye-Sensitised Solar Cell (DSSC). Complexes [Ni(dcbpy)(qdt)] (1), [Ni(decbpy)(qdt)] (2) and [Ni(decbpy)Cl₂] (3) (where dcbpy = 4,4′-dicarboxy-2,2′-bipyridine; decbpy = 4,4′-di(CO₂Et)-2,2′-bipyridine; and qdt = quinoxaline-2,3-dithiolate) have been prepared. Characterisation was carried out using electrochemical, spectroscopic and computational techniques. Intensive visible transitions of 1 and 2 have been assigned predominantly to Ligand-to-Ligand Charge Transfer (LLCT) from the qdt to the diimine ligand, suggesting appropriate charge separation for application in a photoelectrochemical device. TiO₂ sensitised with 2, following charge injection, processes a recombination time significantly long for photovoltaic function. In a DSSC, using redox electrolyte, photocurrents and photovoltages of 0.293 mA and 521 mV were observed, with optimum values requiring TiCl₄ post-treatment of TiO₂ and co-adsorption of Chenodeoxycholic acid (Cheno). Although photovoltaic function was observed, the low photocurrent is attributed to a short-lived excited state lifetime resulting in poor charge injection from the Ni(II) sensitiser.     

Use of Superheated Steam Drying to Increase Strength and Bulk of Papers Produced from Diverse Commercial Furnishes

ABSTRACT

Studies from this laboratory have documented significant changes in properties when paper is dried in superheated steam rather than, as in all current processes, in air. Extending these investigations to additional important pulp types, to recycled pulps and to filled papers, using commercial furnishes from mills, has identified further grades of paper for which drying in superheated steam enhances key properties. For bleached chemithermomechanical pulps and blends with kraft pulp as used for tissue and toweling, strong paper resulted, with 10% higher bulk. Linerboard from 100% recycled old corrugated containers (OCC) is obtained with various strength properties increased by up to 21% with no densification, actually a 4% increase in bulk. Linerboard from high-yield (55–67%) virgin kraft pulps show 23 to 37% increase in strength and toughness. Filled papers containing 0–10% clay can be produced with the same brightness but about 23% higher tensile index when dried in superheated steam.     

Enhanced wide-bandwidth wavelength conversion via feedforward photomixing in semiconductor laser amplifiers

We have investigated a new technique for the enhancement of a wavelength conversion system based on nearly degenerate four wave mixing in a InGaAsP DFB semiconductor laser amplifier. We report enhanced wavelength conversion over 20 nm from 1.55 /spl mu/m to 1.53 /spl mu/m using feedforward photomixing from two independent source lasers to directly modulate the semiconductor laser amplifier. We find that the wavelength conversion efficiency is enhanced by 200% using this technique.     

Modified luque instrumentation after myelomeningocele kyphectomy

STUDY DESIGN: Treatment of congenital kyphosis in myelomeningocele is a difficult problem. Current thinking supports kyphectomy and postoperative internal fixation. OBJECTIVES: Since 1989, vertebral resection with modified Luque fixation has been the procedure of choice for correction of myelomeningocele kyphotic deformity at the author's institution. The study objective was to evaluate long-term results with this technique. SUMMARY OF BACKGROUND DATA: Most investigators agree that kyphotic deformity in myelomeningocele should be treated with vertebral resection. There is less uniform consensus about postoperative fixation. Reports in the literature support fixation with modified segmental instrumentation. METHODS: Sixteen patients, observed for an average of 57.2 months (range, 36-94 months), underwent vertebral resection from the proximal aspect of the apical vertebra cephalad into the compensatory lordotic curve. Fixation was segmental instrumentation wired to the thoracic spine and anterior to the sacrum. RESULTS: The average blood loss was 1121 mL (range, 450-2580 mL). Kyphotic deformity averaged 111 degrees before surgery (range, 75-157 degrees), 15 degrees after surgery (range, -18-36 degrees) and 20 degrees at latest follow-up (range, -17-83 degrees). Loss of correction was 6 degrees (range, 0-27 degrees). Postoperative immobilization was with a thoracolumbosacral orthosis for 18 months. Complications occurring in 8 of the 16 patients were transient headache, superficial wound breakdown, supracondylar femur fractures, and one late infection secondary to skin breakdown that necessitated early rod removal, resulting in some loss of correction. CONCLUSIONS: Kyphectomy is an excellent method of correcting rigid kyphotic deformity in the patient with myelodysplasia. Segmental spinal instrumentation provided three distinct advantages: rigidity of the construct, greater correction of the deformity and low-profile instrumentation.     

PBLs of early breast carcinoma patients with a high nuclear grade tumor unlike PBLs of cervical carcinoma patients do not show a decreased TCR zeta expression but are functionally impaired

BACKGROUND AND OBJECTIVE: The use of hematopoietic growth factors in association with chemotherapy in human immunodeficiency virus (HIV)-related non-Hodgkin's lymphoma (NHL) has been recommended, but few studies have evaluated its cost-effectiveness. DESIGN AND METHODS: The effects of recombinant granulocyte colony-stimulating factor (G-CSF) were analyzed in 33 consecutive patients with HIV-related NHL treated at a single institution with the same chemotherapy program, ProMACE-CytaBOM, with G-CSF, in 21 cases diagnosed after December 31, 1991, or without G-CSF, in 12 cases diagnosed earlier. Pearson's chi-square analysis and the two-sided Student's t-test were used for statistical comparisons. The method of Kaplan-Meyer and the log-rank-test were used for survival analyses. RESULTS: G-CSF support significantly reduced the frequency of day-1 drug dose reductions (p < 0.001) and of chemotherapy delays (p < 0.001), and improved the actual delivered doses of adriamycin, cyclophosphamide and etoposide (p < 0.02). In patients with a CD4+ count < 0.01 x 10(9)/L, chemotherapy could be given at full doses in 90% of cycles with G-CSF compared to only 20% without it. G-CSF affected neither the frequency and duration of fever and hospitalization nor the complete remission and survival rates after stratification according to the CD4+ count. INTERPRETATION AND CONCLUSIONS: G-CSF support significantly improved dose-intensity in patients with HIV-related NHL treated with aggressive chemotherapy, particularly in the subgroup with a CD4+ count < 0.1 x 10(9)/L, but it did not improve their clinical outcome.     

Arousal and attraction: A response-facilitation alternative to misattribution and negative-reinforcement models.

Previous explanations of arousal-attraction phenomena have focused on misattribution and reinforcement processes. Two studies were conducted to test an alternative response-facilitation explanation of these findings. In general, both studies followed previous methods, with the addition of conditions in which Ss' attention was directed to the actual source of their arousal. Study 1 was based on the fear-arousal method used by D. G. Dutton and A. P. Aron (see record 1975-03016-001) and found enhanced attraction to a confederate in high-fear-arousal subjects. Contrary to the misattribution model, the focus-of-attention manipulation had no effect on attraction. Study 2 used a nonthreatening source of arousal (exercise) and also included a focus-of-attention manipulation. Contrary to the misattribution model, arousal facilitated sexual attraction even when subjects' attention was directed to the actual arousal source. Although the results of Study 1 are consistent with a negative-reinforcement model, the findings from Study 2, and from several other studies in the area, are not. The simple response-facilitation model best explains these results and provides a parsimonious alternative explanation for several other sets of data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)