Multiregional Zero Growth Populations with Changing Rates

The theory of stable population dynamics is relatively well developed in the demographic literature, but virtually all of it is founded on the assumption of unchanging rates of fertility, mortality, and migration. The case of changing rates is relatively underdeveloped and little is known about the influence of changing rates on age composition and regional distribution. This paper considers how multiregional zero growth populations evolve over time when exposed to changing birth, death, and migration rates. It illuminates the ways in which an age-by-region composition is influenced by the pattern of recent rates and how the influence of an initial composition is lost over time

Adaptive Transmission Opportunity Scheme Based on Delay Bound and Network Load in IEEE 802.11e Wireless LANs

The IEEE 802.11e EDCA (Enhanced Distributed Channel Access) is able to provide QoS (Quality of Service) by adjusting the transmission opportunities (TXOPs), which control the period to access the medium. The EDCA has a fairness problem among competing stations, which support multimedia applications with different delay bounds. In this paper, we propose a simple and effective scheme for alleviating the fairness problem. The proposed scheme dynamically allocates the TXOP value based on the delay bounds of the data packets in a queue and the traffic load of network. Performance of the proposed scheme is investigated by simulation. Our results show that compared to conventional scheme, the proposed scheme significantly improves network performance, and achieves a high degree of fairness among stations with different multimedia applications

Effect of multilayer barriers on the optical properties of GaInNAs single quantum-well structures grown by metalorganic vapor phase epitaxy

We report on the effects of combined strain-compensating and strain-mediating layers of various widths on the optical properties of 1.3 μm GaInNAs∕GaAs single quantum well structures grown by metalorganic vapor phase epitaxy (MOVPE). While the emission wavelength of GaInNAs∕GaAs quantum wells can be redshifted by the adoption of strain-compensated GaNAs layers, the material quality is degraded by the increased stress at the well∕barrier interface. This detrimental effect can be cured by inserting a strain-mediating InGaAs layer between them. Contrary to what is expected, however, the emission wavelength is blueshifted by the insertion of the InGaAs layer, which is attributed to the reduced N incorporation due to the improved interface quality. Our results indicate that the optical properties of MOVPE-grown GaInNAs∕GaAs quantum wells can be optimized in quantum efficiency and emission wavelength by combination of strain-compensating and strain-mediating layers with suitable characteristics

Effect of dietary mugwort (Artemisia vulgaris L.) and pine needle powder (Pinus densiflora) on growth performance, serum cholesterol levels, and meat quality in broilers

The effects of dietary mugwort and pine needle powder supplementation on growth performance, serum cholesterol, and meat quality of broilers were evaluated in a 35 days feed trial. 200 one day old broilers were randomly allocated to five dietary treatments (0, 1 and 2% mugwort or 1 and 2% pine needle powder) with four replicate pens of 10 birds per treatment. During the experimental period, growth performance did not differ among treatments (P > 0.05). The additives with mugwort and pine needle showed lower crude fat content of thigh muscle compared with the control (P < 0.05); however, no significant differences were detected for moisture, crude protein and crude ash content of thigh muscle. Compared with the control, total phenol content and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity were significantly increased (P < 0.05) with the inclusion of mugwort and pine needle powder level in the broilers’ diets, whereas pH values decreased (P < 0.05). Serum cholesterol and triglyceride concentrations were significantly decreased (P < 0.05) by the increased mugwort and pine needle powder level in the diet, except for high density lipoprotein (HDL) cholesterol concentrations. For thigh meat color, inclusion of mugwort and pine needle powder decreased L* and b* values and increased a* values in thigh muscle of broilers compared with the controls (P < 0.05). Overall, the present study indicates the beneficial effect of using 1 or 2% mugwort and pine needle powder in reducing serum cholesterol and improving meat quality.Key words: Mugwort, pine needle powder, serum cholesterol, meat quality

Laparoscopy-Assisted Resection of Tailgut Cysts: Report of a Case

Tailgut cysts, or retrorectal cystic hamartomas, are rare congenital developmental lesions, most commonly located in the retrorectal space, and are more common in women. We present a case of retrorectal tailgut cyst managed using a laparoscopic approach. A 36-year-old woman presented with incidentally detected retrorectal tumors during evaluation for a gallbladder polyp. Her past medical history revealed that she had undergone cesarean section twice. The tumor marker CA 19-9 level was 42.52 U/ml. CT of the pelvis with contrast and pelvic MRI revealed a 3.9 × 3.3 cm well-defined, homogeneous cystic mass in the right presacral area, and a 2.5 × 1.5 cm cystic mass in the precoccygeal space. The patient underwent laparoscopic exploration with a preoperative diagnosis of tailgut cysts based on radiological findings. The operative time was 90 min including 30 min of subsequent laparoscopic cholecystectomy without placement of additional trocars. The surgical specimens consisted of two fragments of fibrofatty tissues, unilocular cystic masses. The final pathologic diagnosis was tailgut cysts with no evidence of malignancy. Postoperative recovery was uneventful, and the patient was discharged after 3 days. In conclusion, surgical resection is recommended in the management of retrorectal tailgut cyst to establish a definite diagnosis and to rule out malignancy. The laparoscopic approach is a feasible and safe option

Spectroscopic characterization of 1.3µm GaInNAs quantum-well structures grown by metal-organic vapor phase epitaxy

We report optical studies of high-quality 1.3 μm strain-compensated GaInNAs/GaAs single-quantum-well structures grown by metalorganic vapor phase epitaxy. Photoluminescence excitation (PLE) spectroscopy shows clearly the electronic structure of the two-dimensional quantum well. The transition energies between quantized states of the electrons and holes are in agreement with theoretical calculations based on the band anti-crossing model in which the localized N states interact with the extended states in the conduction band. We also investigated the polarization properties of the luminescence by polarized edge-emission measurements. Luminescence bands with different polarization characters arising from the electron to heavy-hole and light-hole transitions, respectively, have been identified and verify the transition assignment observed in the PLE spectrum

Orthogonal polynomials in two variables and second-order partial differential equations

AbstractWe study the second-order partial differential equations L[u] = Auxx +22Buxy + Cuyy + Dux + Euy = λnu, which have orthogonal polynomials in two variables as solutions. By using formal functional calculus on moment functionals, we first give new simpler proofs and improvements of the results by Krall and Sheffer and Littlejohn. We then give a two-variable version of Al-Salam and Chihara's characterization of classical orthogonal polynomials in one variable. We also study in detail the case when L[·] belongs to the basic class, that is, Ay = Cx = 0. In particular, we characterize all such differential equations which have a product of two classical orthogonal polynomials in one variable as solutions

Effect of aspect ratio on convection in a porous enclosure with partially active thermal walls

AbstractThe aim of the present numerical investigation is to understand the effect of aspect ratio and partially thermally active zones on convective flow and heat transfer in a rectangular porous enclosure. Five different heating and cooling zones are considered along the vertical walls while the remaining portions of the sidewalls and top and bottom of the enclosure are adiabatic. The Brinkman–Forchheimer extended Darcy model is used in the study. The governing equations are solved by the finite volume method with the SIMPLE algorithm. The computations are carried out for a wide range of parameters and the results are presented graphically. The results reveal that the location of heating and cooling zones has a significant influence on the flow pattern and the corresponding heat transfer in the enclosure. The rate of heat transfer approaches to a constant value for very low values of the Darcy number. The heat transfer rate is decreased on increasing the aspect ratio

Sectioned images and surface models of a cadaver head with reference to botulinum neurotoxin injection

Background: The aim of this study is to elucidate the anatomical considerations with reference to botulinum neurotoxin type A (BTX) injection, on sectioned images and surface models, using Visible Korean. These can be used for medical education and clinical training in the field of facial surgery.Materials and methods: Serially sectioned images of the head were obtained from a cadaver. Significant anatomic structures in the sectioned images were outlined and assembled to create a surface model.Results: The PDF file (27.8 MB) of the stacked models can be accessed for free. The file can also be obtained from the authors by email. Using this file, important anatomical structures associated with the BTX injection can be investigated in the sectioned images. All surface models and stereoscopic structures related with theBTX injection are described in real time.Conclusions: We hope that these state-of-the-art sectioned images, outlined images, and surface models will assist students and trainees in acquiring a better understanding of the anatomy associated with the BTX injection

Regional Fertility Differentials in IIASA Nations

The evolution of human populations over time and space has been a central concern of many scholars in the Human Settlements and Services Area at IIASA during the past several years. From 1975 through 1978 some of this interest was manifested in the work of the Migration and Settlement Task, which was formally concluded in November 1978. Since then, attention has turned to disseminating the Task's results, to concluding its comparative study, and to exploring possible future activities that might apply the mathematical methodology to other research topics. This paper is part of the Task's dissemination effort. It is a draft of a chapter that is to appear in a volume entitled Migration and Settlement: A Comparative Study. Other selected publications summarizing the work of the Migration and Settlement Task are listed at the back