735,349 research outputs found
The Embryonic Mouse Hindbrain and Postnatal Retina as In Vivo Models to Study Angiogenesis
No full textAngiogenesis, the growth of new blood vessels from pre-existing ones, is a fundamental process for organ development, exercise-induced muscle growth, and wound healing, but is also associated with different diseases such as cancer and neovascular eye disease. Accordingly, elucidating the molecular and cellular mechanisms of angiogenesis has the potential to identify new therapeutic targets to stimulate new vessel formation in ischemic tissues or inhibit pathological vessel growth in disease. This chapter describes the mouse embryo hindbrain and postnatal retina as models to study physiological angiogenesis and provides detailed protocols for tissue dissection, sample staining and analysis
A general framework for pellet reactor modelling : application to P-recovery
No full textEmphasis in recent years has been focused on improving processes which lead to enhanced phosphate recovery. This paper studies the precipitation features of calcium phosphate in a fluidized bed reactor in a concentration range between 4 and 50 mg l 1 and establishes the conditions for optimum phosphate removal efficiency. For this purpose, two models are coupled for predicting the pellet reactor effi ciency. First, a thermodynamical model is used for predicting calcium phosphate precipitation vs. initial conditions (pH, [P], [Ca], temperature). The second one is a reactor network model. Its parameters are identified by an optimization procedure based on simulated annealing and quadratic programming. The efficiency is computed by coupling a simple agglomeration model with a combination of elementary systems representing basic ideal flow patterns (perfect mixed flow, plug flow, etc.). More precisely, the superstructure represents the hydrodynamical conditions in the fluidized bed. The observed results show that a simple combination of ideal flow patterns is involved in pellet reactor modelling, which seems interesting for a future control. The experimental prototype used for validation purpose is first described. Then, the thermochemical model is presented for calcium phosphate precipitation. The third part is devoted to the reactor networkoriented model. The approach presented is finally validated with experimental runs
Living on the edge : Roe deer (Capreolus capreolus) density in the margins of Its geographical range
No full textOver the last decades roe deer (Capreolus capreolus) populations have increased in number and distribution throughout Europe. Such increases have profound impacts on ecosystems, both positive and negative. Therefore monitoring roe deer populations is essential for the appropriate management of this species, in order to achieve a balance between conservation and mitigation of the negative impacts. Despite being required for an effective management plan, the study of roe deer ecology in Portugal is at an early stage, and hence there is still a complete lack of knowledge of roe deer density within its known range. Distance sampling of pellet groups coupled with production and decay rates for pellet groups provided density estimates for roe deer in northeastern Portugal (Lombada National Hunting Area - LNHA, Serra de Montesinho – SM and Serra da Nogueira – SN; LNHA and SM located in Montesinho Natural Park). The estimated roe deer density using a stratified detection function was 1.23/100 ha for LNHA, 4.87/100 ha for SM and 4.25/100 ha in SN, with 95% confidence intervals (CI) of 0.68 to 2.21, 3.08 to 7.71 and 2.25 to 8.03, respectively. For the entire area, the estimated density was about 3.51/100 ha (95% CI - 2.26–5.45). This method can provide estimates of roe deer density, which will ultimately support management decisions. However, effective monitoring should be based on long-term studies that are able to detect population fluctuations. This study represents the initial phase of roe deer monitoring at the edge of its European range and intends to fill the gap in this species ecology, as the gathering of similar data over a number of years will provide the basis for stronger inferences. Monitoring should be continued, although the study area should be increased to evaluate the accuracy of estimates and assess the impact of management actions.Peer reviewe
Evaluating VEGF-Induced Vascular Leakage Using the Miles Assay
No full textBefore the endothelial mitogenic activity of the Vascular Endothelial Growth Factor A (VEGF) was described, VEGF had already been identified for its ability to induce vascular leakage. VEGF-induced vascular leakage has been most frequently studied in vivo using the Miles assay, a simple yet invaluable technique that has allowed researchers to unravel the molecular mechanisms underpinning vascular leakage both for VEGF and other permeability inducing agents. In this protocol, a mouse is intravenously injected with Evans Blue dye before VEGF is administered locally via intradermal injection. VEGF promotes vascular leak of serum proteins in the dermis, enabling Evans Blue-labeled albumin extravasation from the circulation and subsequent accumulation in the skin. As the volume of dye extravasation is proportional to the degree of vascular leak, it can be quantified as a proxy measurement of VEGF-induced vascular leakage
Melting behaviour of iron ore pellet bed under nut coke mixed charge conditions
No full textThe melting and dripping behaviour of an iron ore pellet bed mixed with nut coke are investigated through a series of quenching, melting and dripping experiments. In the melting bed of iron ore pellets, nut coke acts as a frame to maintain the passage for the gas flow. The iron carburisation level of the pellet shell is found to control the melting temperature of the pellet bed. Simultaneous and layer-wise melting is observed for the pellet bed with and without mixed nut coke, respectively.In the case of pellet bed mixed with nut coke, the liquid dripping starts at a lower temperature (1500°C) compared to the case when nut coke is absent (1518°C). Subsequently, a steady rate of liquid dripping is observed for the pellet bed mixed with nut coke. However, in the case of the pellet bed without nut coke, most of the liquid drips (~50 wt%) at high temperature (1550°C). The difference in carbon content of the quenched pellets and the dripped metal reveals that a substantial iron carburisation occurs when liquid iron flows over the regular coke particles.The nut coke is noticed to consumed preferentially in place of the regular coke. Additionally, the total coke consumption decreases with an increase in nut coke addition in the pellet bed. These results give support for more extensive use of nut coke as a replacement of the regular coke in the ironmaking blast furnace.(OLD) MSE-3(OLD) MSE-1Materials Science and Engineerin
Role of Neuropilins in Zebrafish Heart Regeneration
No full textBACKGROUND: Unlike adult mammals, zebrafish can regenerate their heart. Several mechanisms are essential to achieve regeneration; these include: • the de-differentiation and proliferation of cardiomyocytes contributing to new myocardium, • angiogenesis to provide a blood supply to the injured area • epicardial activation, leading to the establishment of a scaffold for the proliferating cardiomyocytes, vessel supporting mural cells and cytokine secretion. Platelet-derived growth factor (Pdgf), Vascular endothelial growth factor (Vegf), Transforming Growth Factor beta (Tgfβ) and Fibroblast growth factor (Fgf) signalling play critical roles in the zebrafish heart regeneration. Neuropilins (NRPs) are cell surface co-receptors that have been implicated in VEGF, PDGF, FGF, TGFβ signalling. AIMS: I hypothesised that neuropilins are required for the regenerative response, and investigated the role of neuropilins in zebrafish heart regeneration following cryoinjury. RESULTS: Zebrafish have four neuropilins isoforms, nrp 1a, 1b, 2a and 2b. I found that all isoforms were upregulated in the ventricle following cardiac cryoinjury. Neuropilins were strongly expressed, at both the mRNA and protein level, by the activated epicardium and endocardium and at the injured/healthy myocardium border. Neuropilin upregulation coincides with leucocyte infiltration to the injured area, epicardial activation and initiation of neovascularisation, implicating a role of nrps in these processes. A nrp1a mutant, encoding a truncated, non-functional protein, showed a significant delay in heart regeneration in comparison to wild type fish. Furthermore, epicardial cells from nrp1a mutant zebrafish heart explants displayed an impaired response to activation by cryoinjury. CONCLUSIONS: Nrp1 plays a key role in zebrafish heart regeneration, mediated through epicardial activation and migration and likely contributes to further physiological processes in other cardiac cell-types. This is the first report of an injury-induced epicardial activation phenotype caused by the disruption of a single allele in zebrafish
P130Cas – a novel mediator for BMP2-driven venous angiogenesis in zebrafish
No full textSprouting angiogenesis, the formation of new blood vessels from existing ones, is critically involved in the cardiovascular development and homeostasis of all higher organisms. While much focus has been directed towards the molecular cues inducing and inhibiting angiogenesis, less research has investigated how endothelial cells transduce these signals and respond accordingly. Our group and others have shown that the adaptor protein P130CAS plays a pivotal role in mediating both endothelial cell and vascular smooth muscle cell proliferation and migration, in response to VEGF and PDGF signalling, respectively. Two in vivo studies in mice found it is absolutely required for embryogenesis as P130CAS-deficient mice die in utero due to cardiac failure or a dysfunctional vasculature. Despite these findings, no further in vivo studies have addressed the cardiovascular function of this adaptor protein. Here, I characterise a novel P130Cas deletion model in the zebrafish. Work presented in this thesis identifies that, in zebrafish, P130Cas activity is dispensable for heart organogenesis and arterial angiogenesis during development. Instead, I found that it is required for venous angiogenesis and lymphangiogenesis. I further present preliminary evidence that P130Cas mediates heart regeneration in the adult zebrafish following cryoinjury, likely through promoting coronary vessel growth. Mechanistically, I present evidence suggesting that in zebrafish, P130Cas mediates Bmp2-induced venous sprouting via Src family kinases. In absence of P130Cas, venous endothelial cells appear to not convert Bmp2b signalling effectively, they are impaired in their ability to form cell protrusions and dynamically detach from neighbouring endothelial cells. This thesis shows that P130Cas transduces venous-specific Bmp2b signalling during sprouting angiogenesis. It also identifies a role for P130CAS in cardiac regeneration, where it is required to replace fibrotic scar tissue with healthy myocardium
The vanishing author in computer-generated works: a critical analysis of recent Australian case law
No full textAbstract
The use of software is ubiquitous in the creation of many copyright works, yet the requirement in copyright law that every work have a human author who engages in independent intellectual effort means that its use may prevent copyright subsistence. Several recent Australian cases have refocused attention on authorship as an essential criterion of copyright subsistence, and these cases suggest that much computer-produced output may be authorless and thus lack copyright protection. This article, the first in a two-part series, analyses how each case deals with the question of authorship of computer-produced works and why the use of software diminishes copyright protection for a significant number of computer-generated works. The article critiques the application of conventional notions of human authorship developed in the pre-computer age to modern productions and suggests alternative approaches to authorship that satisfy both the major objectives of copyright policy and the need to adapt to the computer age. The article argues that, without a broader judicial approach to authorship of computer-generated works, Parliament must remedy the lacuna in protection for these ‘authorless’ works. Possible solutions for reform are suggested. In a forthcoming article, the author comprehensively examines those reform proposals
Fuel pellet production from reed canary grass
No full textThis thesis focuses on two main areas: methods for assessing regional supply potentials of reed canary grass (Phalaris arundinacea L.) (RCG); and process technology for the production of high-quality RCG pellets. Partial equilibrium modelling, incorporating a break-even price approach, was used to examine supply potentials for RCG in Västerbotten County, northern Sweden. A remote sensing method, using black and white orthophoto interpretation, was developed, by which abandoned fields with low preparation costs (on average 173 SEK (ha)-1) could be distinguished from fields with high preparation costs (on average 3990 SEK (ha)-1). Based on the assumptions made, RCG production would predominantly be viable in the coastal area of Västerbotten County, and production equal to 1.3 TWh could be supplied at a farmgate fuel price of 116 SEK MW-1h-1. Pelletizing RCG allows it to be transported, stored and handled more easily. To determine the optimum conditions for RCG pelletizing, experiments were performed in an experimental design incorporating the factors: moisture content, steam addition, raw material density, and die temperature. Pre-compaction of the raw material was an efficient method for avoiding uneven pellet production. Through multiple response optimization, process settings were identified for the production of RCG pellets with a bulk density ≥ 650 kg m-3 and a durability ≥ 97.5%. To clarify the underlying mechanisms in the pelletizing process, the influences of moisture content and normal stress on the kinematic wall friction properties of RCG powder were studied. A steep increase in the kinematic wall friction with increasing normal stress was found in the normal stress interval 50-150 MPa. Multiple linear regression modelling of kinematic wall friction measurements at high normal stresses (65 to 376 MPa) revealed a local maximum at moisture contents of 13–16% and normal stresses of 150–225 MPa. Kinematic wall friction and pellet durability maxima occurred in overlapping moisture content ranges; it was, therefore, hypothesised that the two properties were correlated
Karakteristik Pellet Kayu Sengon
No full textPenelitian ini bertujuan untuk mengetahui karakteristik pellet kayu sengon yang meliputi kadar air, kerapatan, kadar abu, nilai kalor, dan penyalaan pellet kayu sengon. Kayu sengon dibuat serbuk berukuran 22 mesh dengan menggunakan hummer mill. Cetakan pellet yang dibuat memiliki 9 lubang berbentuk selinder dengan ukuran diameter lubang 0,8 cm dan tinggi 6 cm. Setiap lubang diisi sebuk kayu sebanyak 1,5 gram, untuk selanjutnya dipanaskan sampai mencapai suhu perlakuan yaitu 90??C, 110??C, dan 130??C. Sesudah mencapai setiap suhu perlakuan tersebut, serbuk dalam cetakan ditekan dengan tekanan 93 kg/cm??. Sampel yang telah mengalami penekanan, didiamkan selama 20 menit, selanjutnya dikeluarkan dari cetakan. Pembuatan pellet diulang sebanyak 3 kali untuk setiap perlakuan suhu. Hasil penelitian menunjukkan bahwa pada perlakuan suhu 90??C, 110??C, dan 130??C, kadar air pellet masing-masing sebesar 3,87%, 3,55%, dan 3,48%. Kerapatan pellet masing-masing sebesar 790 kg/m??, 880 kg/m??, dan 960 kg/m??. Kadar abu pellet masing-masing sebesar 0,68%, 0,71%, dan 0,73%. Nilai kalor pellet masing-masing sebesar 18,12 MJ/kg, 18,42 MJ/kg, dan 19,08 MJ/kg. Lama penyalaan pellet masing-masing 4,19 detik, 3,51 detik, dan 2,98 detik. Lama pembakaran pellet masing-masing 8,36 menit, 7,15 menit dan 6,03 menit. Kadar air pellet memenuhi standar pellet Austria, Selandia Baru, dan Swedia. Kerapatan pellet memenuhi standar Selandia Baru dan Swedia. Kadar abu pellet memenuhi standar Selandia Baru. Nilai kalor pellet memenuhi standar Austria dan Selandia Baru
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