44 research outputs found
Existence of solutions in the alpha-norm for partial functional differential equations with infinite delay
In this work, we prove a result on the local existence of mild solution in the -norm for some partial functional differential equations with infinite delay. We suppose that the linear part generates a compact analytic semigroup. The nonlinear part is just assumed to be continuous. We use the compactness method, to show the main result of this work. Some application is provided
Incorporation modes of silicon in GaAs: Si grown by metalorganic vapor phase epitaxy
The incorporation of silicon from SiH4
in GaAs has been studied on a wide
range of growth conditions by atmospheric
pressure metalorganic vapor phase
epitaxy (AP-MOVPE). The highest
free carrier concentration exceeds
1 × 1019 cm−3. Compensation ratios appear
to be strongly dependent on the SiH4
partial pressure. The relatively high
compensation ratios essentially originate
from the amphoteric behaviour of silicon.
The temperature dependence of
silicon doping has been investigated in
the range 650 °C to 765 °C with various
silane partial pressures. The
activation energy of Si incorporation varies from
0 to 2.2 eV. The dependence of the free
electron concentration on the arsine
partial pressure (PAsH3) leads to the empirical relationship:
n = aPAsH3 + bP_{AsH_3}^{-\frac{4}{3},
which describes the relationship between silicon doping
concentration and arsine partial pressure
Effects of thermal annealing on n-type GaAs : V grown by MOCVD
International audienceVanadium (V)-doped GaAs (GaAs:V) layers grown by metal-organic chemical vapour deposition under different V-doping levels (10(17)-10(19) cm(-3)) were annealed in an arsine-H-2 gas mixture up to annealing temperatures of 750 and 850 degrees C for 30 min. The effect of thermal treatments on their electrical and optical properties was studied by means of the Hall effect, deep level transient spectroscopy and photoluminescence (PL). Annealing at 750 degrees C induces a thermal conversion from the n- to p-type of weakly V-doped GaAs. The conductivity of highly V-doped materials remains n-type. All the V-doped samples convert from n- to p-type following annealing at 850 degrees C. A comparison between the PL spectra for materials annealed under different conditions underlines the important role of gallium vacancies and a possible V accumulation at the surface in the case of thermal conversion
New photoluminescence lines in Vanadium doped GaAs grown by MOVPE
We examined the electrical and optical properties of vanadium-doped GaAs grown by metalorganic vapour phase epitaxy using vanadium tetrachloride (VCl4) as a novel dopant source. Samples with various vanadium incorporations were investigated. All samples were n type. The electron concentration dependence on the VCl4 flow rate was established. At 15 K, by comparison with undoped layers grown in the same conditions, photoluminescence spectra of V-doped exhibited three new emission bands: at 1.41, 1 and 0.72 eV. The 1 and 0.72 eV band emissions were attributed to V2+ and V3+ intracenter emission, while the 1.41 eV band was suggested to be a donor-bound transition. The identity of the donor is tentatively attributed to a donor complex that associates vanadium to an arsenic vacancy. From Hall effect as function of temperature, the donor ionisation energy was estimated to be about 102±5 meV
The three questions : King James 11, the Penal Laws and Test Acts, and the landed classes, 1687-88
The purpose of this thesis is to look afresh at James 11's canvassing of the gentry in the winter of 1687-8 on the repeal of the Test Acts and the penal laws. The Tests prevented non-Anglicans in general, but Catholics in particular, from participating fully in public life. The penal laws punished those who did not conform to the Established Church. As a Catholic, James was anxious to ease the lot of his co-religionists and by the third year of his reign he had shown himself willing to extend toleration to Protestant Dissenters. The canvass was part of the campaign to find a Parliament willing to repeal these laws. Historians have viewed the canvass as a failure: certainly it did not bring the results the King hoped for and helped to create a united opposition to the Stuart regime. But on closer inspection the returns reveal a more confused picture. More members of the gentry supported repeal than was originally believed and with these supporters the King was able to begin to fashion alternative local political administrations that might in time have challenged the entrenched political interests in the shires. However, this new power base was still too narrow by the time William of Orange intervened in English politics, mainly because the King, by his ruthless purging of local office-holders, missed the opportunity to win over gentlemen who, given the right encouragement, might have come to support repeal. But it is in the answers to the third question, in which an overwhelming majority of gentlemen endorsed the general concept of religious toleration, that a sea change in attitudes among the political classes is revealed, something the King might have been able to build on if he had had the time or inclination to nurture the 'green shoots' of religious pluralism.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Optical characterization by photoreflectance of GaN after its partial thermal decomposition
International audienc
Role of thoracoscopic pleural lavage and brush in undiagnosed exudative pleural effusion
Background: The accurate diagnosis of pleural effusion remains a challenging problem even after thoracentesis and closed pleural biopsy. Medical thoracoscopy has been established to have a greater diagnostic yield in the diagnosis of exudative pleural effusion. Forceps biopsy, pleural brush and lavage could be used through medical thoracoscopy to obtain pleural specimens.
Objective: The aim of this study is to evaluate the role of thoracoscopic pleural lavage and brush in undiagnosed exudative pleural effusion.
Patients and methods: This prospective study was carried out on 25 patients having undiagnosed exudative pleural effusion. All patients submitted to medical thoracoscopy, where forceps biopsy, pleural brush and pleural lavage specimens were taken for all patients and sent for histopathological and cytological examination.
Results: Combined thoracoscopic pleural specimens were diagnostic in 24 patients (96%), and all of them were malignant. Forceps biopsy was positive in 23 patients (92%), while pleural brush and pleural lavage were positive in 18 patients (72%) and 15 patients (60%) respectively. Pleural brush was the only diagnostic modality in one patient. Minimal complications were recorded.
Conclusion: Combined thoracoscopic pleural specimens (forceps biopsy, brush and lavage) increase the diagnostic yield of medical thoracoscopy for patients with undiagnosed exudative pleural effusion than separate them. Thoracoscopic pleural brushing is a safe diagnostic technique as it can brush certain dangerous areas of the pleura. Pleural lavage is more diagnostic than the initial thoracentesis