To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Audiometric tests do not adequately reflect the hearing handicap experienced by individuals with hearing loss and account for only part of the variance in hearing handicap perceptions (Weinstein & Ventry, 1983). The present study investigates the relationship between degree of hearing impairment, psychosocial factors and hearing handicap in a New Zealand war veteran sample. Forty-seven veterans (Mean age = 77.51, SD = 5.99) with some degree of hearing impairment completed a questionnaire which included the Hearing Handicap Inventory (HHI) (Newman et al., 1990), the SF36 sub-scales for general health and mental health (Ware, Kosinski & Keller, 1994), questions relating to hearing aid use and demographic details. Audiometric test information for each veteran was accessed through the national war pensions organisation. Analyses revealed no significant relationship between percentage hearing loss and perceptions of hearing handicap. Those who reported lower satisfaction with their hearing aids, those in poorer physical health and those who had been using hearing aids for a longer time reported higher scores on the HHI. These findings suggest that aspects of the rehabilitation process are important factors in the individual's experience of hearing handicap and that non-auditory factors (such as general health) may be essential considerations in this process.
To assess the feasibility and clinical value of using the CellSearch system to detect circulating tumour cells in patients with advanced-stage head and neck squamous cell carcinoma.
Circulating tumour cells were isolated and counted via positive selection utilising magnetically labelled anti-epithelial cell adhesion molecule and immunocytochemical staining for cytokeratin. The correlation between circulating tumour cell presence and clinical features was evaluated in nine patients newly diagnosed with advanced-stage (stage III or IV) head and neck squamous cell carcinoma.
Circulating tumour cells were detected in three of the nine patients (33 per cent). Circulating tumour cell positivity was more prevalent in node stage 2 to 3 patients (3 of 5, 60 per cent) than node stage 0 to 1 patients (0 of 4, 0 per cent). Recurrent or progressive disease was observed in only one of the six patients (17 per cent) without circulating tumour cells, compared with two of the three patients (67 per cent) with circulating tumour cells.
In this preliminary study, circulating tumour cells were successfully isolated in patients with advanced-stage head and neck squamous cell carcinoma, using the CellSearch system. Further investigation is needed to evaluate the prognostic significance of circulating tumour cells.
A sample preparation method is described for enabling direct correlation of site-specific plan-view and cross-sectional transmission electron microscopy (TEM) analysis of individual nanostructures by employing a dual-beam focused-ion beam (FIB) microscope. This technique is demonstrated using Si nanowires dispersed on a TEM sample support (lacey carbon or Si-nitride). Individual nanowires are first imaged in the plan-view orientation to identify a region of interest; in this case, impurity atoms distributed at crystalline defects that require further investigation in the cross-sectional orientation. Subsequently, the region of interest is capped with a series of ex situ and in situ deposited layers to protect the nanowire and facilitate site-specific lift-out and cross-sectioning using a dual-beam FIB microscope. The lift-out specimen is thinned to electron transparency with site-specific positioning to within ∼200 nm of a target position along the length of the nanowire. Using the described technique, it is possible to produce correlated plan-view and cross-sectional view lattice-resolved TEM images that enable a quasi-3D analysis of crystalline defect structures in a specific nanowire. While the current study is focused on nanowires, the procedure described herein is general for any electron-transparent sample and is broadly applicable for many nanostructures, such as nanowires, nanoparticles, patterned thin films, and devices.
We report the chemical synthesis of Fe-core/Au-shell nanoparticles (Fe/Au) by a reverse micelle method, and the investigation of their growth mechanisms and oxidation-resistant characteristics. The core-shell structure and the presence of the Fe and Au phases have been confirmed by transmission electron microscopy, energy dispersive spectroscopy, x-ray diffraction, Mössbauer spectroscopy, and inductively coupled plasma techniques. Additionally, atomic-resolution Z-contrast imaging and electron energy loss spectroscopy in a scanning transmission electron microscope have been used to study details of the growth processes. The Au-shells grow by nucleating on the Fe-core surfaces before coalescing. First-order reversal curves, along with the major hysteresis loops of the Fe/Au nanoparticles have been measured as a function of time in order to investigate the evolution of their magnetic properties. The magnetic moments of such nanoparticles, in the loose powder form, decrease over time due to oxidation. The less than ideal oxidation-resistance of the Au shell may have been caused by the rough Au surfaces. In a small fraction of the particles, off-centered Fe cores have been observed, which are more susceptible to oxidation. However, in the pressed pellet form, electrical transport measurements show that the particles are fairly stable, as the resistance and magnetoresistance of the pellet do not change appreciably over time. Our results demonstrate the complexity involved in the synthesis and properties of these heterostructured nanoparticles.
Solvothermal/hydrothermal reactions of 4, 4′-biphenyldicarboxylic acid (H2bpdc) and cobalt (II) salt with pyridine derivative ligands such as 3-methylpyridine (3-pic), 4-methylpyridine (4-pic), as well as a longer terminal ligand 4-benzylpyridine (4-bzpy) generated four new extended structures: 1D zigzag polymer chain 1 crystallized in C2/c with a formula [Co(bpdc)(3-pic)2]·(3-pic); 1D helical chain compound 2 crystallized in P41 with a formula [Co(bpdc)(4-pic)2], 2D non-interpenetrating network 3 crystallized in P2221 with a formula [Co(bpdc)(4-pic)2]·(4-pic)0.5·H2O, and 2D non-interpenetrating network 4 crystallized in P2/c, formulated as [Co(bpdc)(bzpy)2]. Our studies show that terminal ligands play an important role in affecting the dimensionality and topology of the structures formed. Magnetic susceptibility and isothermal magnetization results revealed an antiferromagnetic ground state for 3 with a transition temperature T = 4.7 K, and paramagnetic behavior at high temperature range for 1 and 2.
The effect of the laser energy density used to deposit Bi onto amorphous aluminum oxide (a-Al2O3) on the growth of Bi nanocrystals has been investigated using transmission electron microscopy of cross section samples. The laser energy density on the Bi target was varied by one order of magnitude (0.4 to 5 J cm-2). Across the range of energy densities, in addition to the Bi nanocrystals nucleated on the a-Al2O3 surface, a dark and apparently continuous layer appears below the nanocrystals. Energy dispersive X-ray analysis on the layer have shown it is Bi rich. The separation from the Bi layer to the bottom of the nanocrystals on top is consistent with the implantation range of Bi species in a-Al2O3. As the laser energy density increases, the implantation range has been measured to increase. The early stages of the Bi growth have been analyzed in order to determine how the Bi implanted layer develops.
High levels of dietary concentrates are often used to support milk production and it is important to investigate ways to feed them efficiently. Fats have the greatest energy density of any feed ingredient and the inclusion of protected fats in the dairy cow ration enables a high energy but balanced ration to be fed. The aim of this trial was to investigate the effect of feeding different levels of Megalac (Volac International Ltd, Herts) to dairy cows and to compare milk yield, milk composition, fertility and body condition score (BCS).
In recent years there has been a high degree of interest in multilayer film (MLF) structures because of their applications as magnetoresistive sensors and as memory elements in magnetoresistive random access memory arrays. As each of the layers in a spin-valve-based MLF structure1 is only a few nanometers in thickness, the morphology of the layers is crucial in controlling the magnetic and transport properties of the devices. In general, the microstructural features that can influence the film properties include layer roughness, layer composition, interfacial chemical mixing, grain size, grain boundary morphology, and crystallographic orientation, with the most important microstructural parameter being the nature of the interfaces between adjacent layers. With so many internal interfaces, each of which can have a different morphology and degree of intermixing, it is extremely difficult to determine the nature of each individual interface unless a technique is used that can analyze them independently, and with high spatial resolution.
Mathematical programming-based systems analysis is used to examine the consequences of alternative operation configuration for the agricultural operations within the Texas Department of Criminal Justice. Continuation versus elimination of the total operation as well as individual operating departments are considered. Methodology includes a firm systems operation model combined with capital budgeting and an integer programming based investment model. Results indicate the resources realize a positive return as a whole, but some enterprises are not using resources profitably. The integer investment model is found to be superior for investigating whether to continue multiple interrelated enterprises.
Affordable, high quality SiC wafers are very desirable for a variety of new technologies including GaN based lighting, RF, and high-power electronics based on wide band gap materials. At Litton Airtron we have a major effort in the growth and characterization of SiC. We will present data on 35, 50 and 75-mm diameter crystals. We are growing both n-type, semiinsulating 4H, 6H, and 15R material. A variety of characterization techniques are being used at Litton Airtron to determine wafer quality. These include Raman microscopy, digital wafer photography, and crossed polarizer images. Raman spectroscopy is an excellent probe of polytype and carrier concentration for n-type materials; in addition it can be done at room temperature and is sufficiently fast that it can be used in an industrial environment. The use of digital photography allows for the collection of images that can be quantitatively analyzed and archived.
Centrally administered glucagon-like peptide-1 (GLP-1) inhibits feeding in fasted rats, but its role in human satiety has been largely unexplored. The present study investigated the effect of peripheral GLP-1 infusion on gastric emptying and satiety in man. Ten non-obese male subjects were infused in a randomized single-blind within-subject crossover study using saline infusion as control. They received either a GLP-1 infusion (1·2 pmol/kg per min) or a saline infusion for 1 h, at 18.00 hours. At 20 min after starting the infusion the gastric emptying of a 400 ml water load was measured. Subjects completed behavioural self-rating scales to assess hunger and satiety. After 40 min subjects were given a buffet meal ad libitum and their food intake was recorded. GLP-1 infusion raised circulating GLP-1 concentrations to approximately twice those seen following a meal. It did not affect circulating insulin levels but caused a small fall in glucose levels. Gastric emptying of the water load was significantly delayed by the GLP-1 infusion. Energy intake from the buffet was unaffected by GLP-1 infusion. Self-assessment of hunger and satiety was similarly unaffected by the infusion before the buffet meal, although subjects tended to be less hungry after the buffet meal following GLP-1 infusion (P < 0·09). GLP-1 infusion delayed gastric emptying but had a minimal effect on food intake and satiety. This study casts doubts on whether GLP-1 is a major satiety factor in man, although a raised circulating plasma glucose level, as would normally occur postprandially, might be necessary for GLP-1 to increase satiety.
The Earth is within the Contemporaneous Solar Maximum (CSM), analogous to the Medieval Solar Maximum (MSM). If this analogy is valid, solar activity will continue to increase well into the 21st century. We have completed 75 single-ring and 10 double-ring measurements from ad 1065 to ad 1150 to obtain information about solar activity during this postulated analog to solar activity during the MSM. δ14C decreases steadily during the period ad 1065 to ad 1150 but with cyclical oscillations around the decreasing trend. These oscillations can be successfully modeled by four cycles. These four frequencies are 1/52 yr-1, 1/22 yr-1, 1/11 yr-1, and 1/5.5 yr, i.e., the 4th harmonic of the Suess cycle, the Hale and Schwabe cycles and the 2nd harmonic of the Schwabe cycle.
Lanthanum gallate is a promising material for “monolithic” fuel cells or oxygen pumps, i.e. one in which the electrolyte and electrodes are formed from a common phase. We have investigated La1−xSrxGa1–yNiyO3 (LSGNx-y) with x=0.1 and y=0.2 and 0.5 as a potential cathode material for such an electrochemical device. The σ(PO2,T) for LSGN10–20 points to a p-type electronic conductivity at high PO2 and predominantly ionic conductivity at low PO2. LSGN10–50 has an electronic conductivity suitable for SOFC applications of approximately 50 S/cm in air at high temperature. AC impedance spectroscopy on an electron blocking cell of the form M/LSG/LSGN/LSG/M was used to isolate the ionic conductivity in the LSGN10–20 material. The ionic conductivity was found to have a similar magnitude and activation energy to that of undoped LSG material with σi= 0.12 S/cm at 800°C and EA= 1.0 ± 0.1 eV. Thermal expansion measurements on the LSGN materials were characterized as a function of temperature and dopant level and were found to match that of the electrolyte under opeating conditions.
We report on an investigation into the interfacial structure of undoped GaInAs/GaInAsP multiple quantum wells grown by metalorganic chemical vapour deposition (MOCVD), which exhibit a pronounced blue shift in luminescence output upon in-situ thermal annealing at 750°C. Using a recently developed composition mapping technique based on the scanning transmission electron microscope (STEM) in conjunction with energy dispersive X-ray (EDX) analysis, the constituent element concentration profiles across the interdiffused multilayer interfaces are measured with a spatial resolution of less than 2nm and a precision of better than 2–3%. The accuracy of the analysis is significantly improved by employing stoichiometric normalisation factors which compensate for systematic errors due to electron channelling. The results showed that the interdiffusion follows a highly non-linear path due to the relatively fast diffusion of the group V species compared to that of the group III species. This implies an increase in the coherency strain in the multilayer, a result which is supported by five-crystal Xray diffraction analysis of the layers. The samples have also been examined by high resolution electron microscopy (HREM) under chemically sensitive imaging conditions. The analysis of the interfacial chemical profile using HREM must be performed under analysis conditions for which a known and unique relationship between image contrast and composition occurs. This condition may not be satisfied in cases in which more than two chemical constituents interdiffuse and the diffusivities of these elements are not equal, as a range of similar lattice fringe motifs across the interface, representing different “diffusion paths”, could occur. The complementary nature of information provided by HREM and STEM provides a means of resolving this ambiguity.
The pulsed-laser induced photochemical production of metallic Ga islands on the surface of GaAs cleaved, irradiated, and studied in ultrahigh vacuum (UHV) is documented through photoelectron spectroscopy and subsequent scanning electron microscopy. Ga islands are detected for laser fluences as low as 1 mJ/cm2, far below those previously reported for modification of GaAs, and for which the temperature rise is negligible.
The paper reviews a number of X-ray streak cameras developed at AWRE. These cameras are used to provide temporal and one-dimensional spatial or spectral information on X-rays emitted from laser produced plasmas. Two of these cameras have been designed to be combined with other diagnostic instrumentation; one with a Wolter X-ray microscope (×22 magnification) and the other with a Bragg diffraction crystal spectrometer. This latter instrument provides a few eV spectral resolution and ∼15 ps temporal resolution; a typical experimental application at the AWRE HELEN laser facility will be described. The paper describes the circuitry of the bipolar avalanche transistor ramp generator used to drive the streak plates of the cameras. Improvements to this include: (a) increasing the fastest streak rate to ∼10 ps mm−1 by a distributed capacitance network across each of the bipolar stacks of transistors, and (b) reducing the trigger jitter to approximately ±10 ps by the use of a new mix of transistors in the stack and a Raytheon RS 3500 avalanche transistor. Additional improvements have now been added. These include a ‘half-scan’ user facility to aid initial camera timing and direct switching to select the sweep rate of the camera.
Evidence for a new microcrystalline precipitate in CZ Si annealed for 256 hrs at 635°C is presented by electron microdiffraction. This may be a precursor phase for the formation of amorphous platelets . Multiple scattering microdiffraction calculations which distinguish the symmetries of two models for the thermal donor are also given.
Spectra of photoelectrons and thermionic electrons emitted from silicon during pulsed laser irradiation at energy densities encompassing the thresholds for laser annealing and damage are reported. Annealing is accomplished with a 90-nsec pulse of 532-nm light, which may be accompanied by a 266-nm probe pulse. A cylindrical mirror analyzer is used for energy resolution of emitted electrons. Time-resolved reflectivity at 633 nm verifies attainment of the high-reflectivity annealing phase. Spectral widths and total yields imply a modest electron temperature (T < 3000 K) during annealing. The data suggest that the work function of the silicon (111) face may increase about 0.6 eV upon transition to the molten phase.
Upper flux limits at the earth for γ rays of energy greater than about 5 × 1012 eV, have been established for the quasi-stellar sources 3C 147, 3C 196, 3C 273, the Crab Nebula, and the magnetic variable 53 Cam. They are all of the order 10-10 photons cm-2. s-1. Corresponding upper energy limits at emission are of the order 5 × 1047 ergs s-1 for the quasi-stellar sources, and 5 × 1035 ergs s-1 for the Crab Nebula, if γ-ray absorption is assumed negligible. Possible absorption mechanisms are discussed.