5,050 research outputs found
Optimising a fall out dust monitoring sampling programme at a cement manufacturing plant in South Africa
The aim of this study at the specific cement manufacturing plant and open cast mine was to develop a positioning guideline for monitoring equipment and to optimise the fall out dust sampling programme. A baseline study was conducted on existing practices and legal requirements relating to fall out dust monitoring. The different methods and techniques for the identification of particulate emission sources and the calculation of emission rates were evaluated in order to identify the simplest and most cost effective options. Due to the complexity of sampling particulate emissions, emission factors and existing stack monitoring results were used to calculate the emissions. The quantified point and fugitive emissions rates were used to populate a dust dispersion model and the modeling results were compared with the existing monitoring program results. Due to the complexity of actual measurements or applying the principles of a mass balance in the total cement manufacturing process to calculate emission rates it was found that the selected use of emission factors is a simpler and less costly method. The study concluded that, after superimposing the dispersion model to the results from the existing sampling positions, existing sampling positions are not optimally located. A guideline for the optimisation of a fall out dust monitoring program is proposed.Key words: Fall out dust monitoring, cement plant, optimising, air pollution sampling, fall out dust sampler locations
Empfehlungen notwendiger Kontrolluntersuchungen bei okulÀrer Hypertension
Zusammenfassung: Die okulĂ€re Hypertension bezeichnet einen ĂŒber die "Norm" (â>â21mmHg) erhöhten Intraokulardruck (IOD). Der Kammerwinkel ist definitionsgemÀà offen, glaukomtypische GesichtsfeldausfĂ€lle und PapillenverĂ€nderungen fehlen. Es handelt sich um Individuen, die nicht an einem Glaukom leiden, wohl aber ein erhöhtes Risiko haben, ein Glaukom zu entwickeln. Um glaukomtypische GesichtsfeldausfĂ€lle und PapillenverĂ€nderungen auszuschlieĂen, ist eine ausfĂŒhrliche "Glaukombasisdiagnostik" unabdingbar. Aufgrund des erhöhten Risikos, ein Glaukom zu entwickeln, sind feste Kontrollintervalle und eine standardisierte Untersuchung fĂŒr das Follow-up ebenso zwingend erforderlic
Wirksamkeit der selektiven Lasertrabekuloplastik bei Patienten mit unzureichender Augendrucksenkung unter maximaler Therapie
Zusammenfassung: Hintergrund: Hauptziel der Glaukomtherapie ist die Senkung des Intraokulardruckes (IOD). Ziel dieser prospektiven Studie war es, die IOD-senkende Wirkung der selektiven Lasertrabekuloplastik (SLT) bei Patienten unter maximaler medikamentöser Therapie (MMT) zu untersuchen. Spezielles Augenmerk wurde auf eine mögliche Wechselwirkung mit Pseudophakie oder Prostaglandintherapie (PGT) gelegt. Material und Methoden: Bei 30Patienten mit primĂ€rem Offenwinkelglaukom, Normaldruckglaukom und Pseudoexfoliationsglaukom mit unzureichender IOD-Senkung unter MMT wurde eine SLT ĂŒber 360° Zirkumferenz durchgefĂŒhrt. Verlaufskontrollen fanden nach 1Tag sowie nach 1, 3, 6, 9 und 12Monaten statt. Die IOD-senkende Therapie wurde ĂŒber 3Monate unverĂ€ndert weitergefĂŒhrt. Ergebnisse: Die mittlere Verlaufsbeobachtungszeit betrug 11,97â±â3,1Monate. Der mittlere IOD vor SLT war 19,60â±â4,69mmHg. Die mittlere IOD-Senkung war â19,95â±â17,14% nach 1Monat (p<0,001) sowie â14,07â±â23,57% nach 12Monaten (p=0,003). Patienten mit einem höheren prĂ€operativen IOD hatten eine stĂ€rker ausgeprĂ€gte Drucksenkung (R2=0,482; p<0,001). Phake Patienten hatten eine signifikant ausgeprĂ€gtere IOD-Senkung im Vergleich zu pseudophaken Patienten (-4,55±4,45mmHg bzw. +2,75±6,75mmHg; p=0,010). Patienten ohne PGT hatten eine statistisch knapp nicht signifikant ausgeprĂ€gtere IOD-Senkung im Vergleich zu Patienten mit PGT (-7,40±4,72mmHg bzw. -2,48±5,22mmHg; p=0,066). Vier Patienten benötigten einen weiteren IOD-senkenden Eingriff. Schlussfolgerung: Bei Patienten unter MMT kann durch eine SLT der IOD bis zu 1Jahr noch signifikant gesenkt werden. Die IOD-senkende Wirkung ist bei phaken Patienten mit hohem Ausgangsdruck am stĂ€rksten ausgeprĂ€g
1-Jahres-Ergebnisse nach kombinierter Kataraktoperation und Excimer-Laser-Trabekulotomie bei erhöhtem Intraokulardruck
Zusammenfassung: Hintergrund: Glaukom ist eine der hĂ€ufigsten Ursachen fĂŒr Blindheit. Normalerweise ist ein erhöhter Abflusswiderstand die Ursache, wĂ€hrend die Kammerwasserproduktion normal bleibt. Medikamentöse Drucksenkung ist in der Regel die First-line-Behandlung. Der operative Goldstandard ist die Trabekulektomie (TE). Die TE hat jedoch zahlreiche postoperative Komplikationen. Deswegen bevorzugen wir fĂŒr ausgesuchte Glaukompatienten die kombinierte Kataraktoperation mit der Excimer-Laser-Trabekulotomie (Phako-ELT). Indikationen sind eine Katarakt und gleichzeitig ein moderat erhöhter Intraokulardruck (IOD) ohne medikamentöse Therapie oder eine moderate Katarakt mit erhöhtem IOD trotz medikamentöser Therapie. Patienten und Methoden: Im Rahmen der ELT werden 10Poren ĂŒber einen Winkel von 90° im Trabekelmaschenwerk erzeugt. Es wurden 28Augen von 28Patienten (10MĂ€nner, 18Frauen) 12Monate± 2Wochen nach kombinierter Phako-ELT nachuntersucht. Vier Patienten wurden wegen einer drucksenkenden Reoperation wĂ€hrend des Nachbeobachtungszeitraums ausgeschlossen. Intraokulardruck, bestkorrigierter Visus und Anzahl der Glaukommedikamente ("anti-glaucoma drugs", AGD) wurden erhoben und eine Spaltlampenuntersuchung durchgefĂŒhrt. Ergebnisse: Das Durchschnittsalter lag bei 74,33±11,81Jahren. Diagnosen waren primĂ€res Offenwinkelglaukom bei 9Augen, Pseudoexfoliationsglaukom bei 15Augen, okulĂ€re Hypertension und posttraumatisches SekundĂ€rglaukom bei 3 bzw. 1Auge. Im Durchschnitt konnte durch Phako-ELT der IOD um 8,79±5,28mmHg (â34,70%, p<0,001) gesenkt werden. Die Anzahl der AGD konnte gleichzeitig um 0,79±1,50 (â62,70%, p=0,017) reduziert werden. Schlussfolgerungen: Eine ELT ist technisch einfach am Ende einer Kataraktoperation durchzufĂŒhren. Die Operationszeit wird lediglich um 2-3min verlĂ€ngert. Wir fanden eine durchschnittliche IOD-Reduktion von 8,79mmHg (â34,70%) und gleichzeitig eine durchschnittliche Reduktion von AGD um 0,79. Es ist bekannt, dass der Effekt der IOD-Reduktion konstant mit der Zeit ist im Gegensatz zur Argon- oder selektiven Laser-Trabekuloplastik. Eine evtl. spĂ€tere fistulierende Operation ist nicht beeintrĂ€chtigt, da die Bindehaut nicht berĂŒhrt wird und es folglich keine Vernarbung gibt. FĂŒr ausgewĂ€hlte Glaukompatienten ist diese Operation eine Möglichkeit, die Trabekulektomie zu vermeide
Ghost Busting: PT-Symmetric Interpretation of the Lee Model
The Lee model was introduced in the 1950s as an elementary quantum field
theory in which mass, wave function, and charge renormalization could be
carried out exactly. In early studies of this model it was found that there is
a critical value of g^2, the square of the renormalized coupling constant,
above which g_0^2, the square of the unrenormalized coupling constant, is
negative. Thus, for g^2 larger than this critical value, the Hamiltonian of the
Lee model becomes non-Hermitian. It was also discovered that in this
non-Hermitian regime a new state appears whose norm is negative. This state is
called a ghost state. It has always been assumed that in this ghost regime the
Lee model is an unacceptable quantum theory because unitarity appears to be
violated. However, in this regime while the Hamiltonian is not Hermitian, it
does possess PT symmetry. It has recently been discovered that a non-Hermitian
Hamiltonian having PT symmetry may define a quantum theory that is unitary. The
proof of unitarity requires the construction of a new time-independent operator
called C. In terms of C one can define a new inner product with respect to
which the norms of the states in the Hilbert space are positive. Furthermore,
it has been shown that time evolution in such a theory is unitary. In this
paper the C operator for the Lee model in the ghost regime is constructed
exactly in the V/N-theta sector. It is then shown that the ghost state has a
positive norm and that the Lee model is an acceptable unitary quantum field
theory for all values of g^2.Comment: 20 pages, 9 figure
Squeezed Light for the Interferometric Detection of High Frequency Gravitational Waves
The quantum noise of the light field is a fundamental noise source in
interferometric gravitational wave detectors. Injected squeezed light is
capable of reducing the quantum noise contribution to the detector noise floor
to values that surpass the so-called Standard-Quantum-Limit (SQL). In
particular, squeezed light is useful for the detection of gravitational waves
at high frequencies where interferometers are typically shot-noise limited,
although the SQL might not be beaten in this case. We theoretically analyze the
quantum noise of the signal-recycled laser interferometric gravitational-wave
detector GEO600 with additional input and output optics, namely
frequency-dependent squeezing of the vacuum state of light entering the dark
port and frequency-dependent homodyne detection. We focus on the frequency
range between 1 kHz and 10 kHz, where, although signal recycled, the detector
is still shot-noise limited. It is found that the GEO600 detector with present
design parameters will benefit from frequency dependent squeezed light.
Assuming a squeezing strength of -6 dB in quantum noise variance, the
interferometer will become thermal noise limited up to 4 kHz without further
reduction of bandwidth. At higher frequencies the linear noise spectral density
of GEO600 will still be dominated by shot-noise and improved by a factor of
10^{6dB/20dB}~2 according to the squeezing strength assumed. The interferometer
might reach a strain sensitivity of 6x10^{-23} above 1 kHz (tunable) with a
bandwidth of around 350 Hz. We propose a scheme to implement the desired
frequency dependent squeezing by introducing an additional optical component to
GEO600s signal-recycling cavity.Comment: Presentation at AMALDI Conference 2003 in Pis
Big Bang Observer and the neutron-star-binary subtraction problem
The Big Bang Observer (BBO) is a proposed space-based gravitational-wave (GW) mission designed primarily to search for an inflation-generated GW background in the frequency range ~10-1 Hzâ1 Hz. The major astrophysical foreground in this range is gravitational radiation from inspiralling compact binaries. This foreground is expected to be much larger than the inflation-generated background, so to accomplish its main goal, BBO must be sensitive enough to identify and subtract out practically all such binaries in the observable universe. It is somewhat subtle to decide whether BBO's current baseline design is sufficiently sensitive for this task, since, at least initially, the dominant noise source impeding identification of any one binary is confusion noise from all the others (rather than instrumental noise). Here we present a self-consistent scheme for deciding whether BBO's baseline design is indeed adequate for subtracting out the binary foreground. We conclude that the current baseline should be sufficient. However, if BBO's sensitivity were degraded by a factor 2 from the current baseline, then its ability to detect an underlying primordial background would depend critically on the value of rhoth, the threshold signal-to-noise ratio marking the boundary between detectable and undetectable sources. If BBO's sensitivity were degraded by a factor 4 from the current baseline, it could not detect a primordial background below OmegaGW~10-15. It is impossible to perfectly subtract out each of the binary inspiral waveforms, so an important question is how to deal with the "residual" errors in the post-subtraction data stream. We sketch a strategy of "projecting out" these residual errors, at the cost of some effective bandwidth. We also provide estimates of the sizes of various post-Newtonian effects in the inspiral waveforms that must be accounted for in the BBO analysis
Perturbations in the Kerr-Newman Dilatonic Black Hole Background: Maxwell Waves, the Dilaton Background and Gravitational Lensing
In this paper we continue the analysis of our previous papers and study the
affect of the existence of a non-trivial dilaton background on the propagation
of electromagnetic waves in the Kerr-Newman dilatonic black hole space-time.
For this purpose we again employ the double expansion in both the background
electric charge and the wave parameters of the relevant quantities in the
Newman-Penrose formalism and then identify the first order at which the dilaton
background enters the Maxwell equations. We then assume that gravitational and
dilatonic waves are negligible (at that order in the charge parameter) with
respect to electromagnetic waves and argue that this condition is consistent
with the solutions already found in the previous paper. Explicit expressions
are given for the asymptotic behavior of scattered waves, and a simple physical
model is proposed in order to test the effects. An expression for the relative
intensity is obtained for Reissner-Nordstrom dilaton black holes using
geometrical optics. A comparison with the approximation of geometrical optics
for Kerr-Newman dilaton black holes shows that at the order to which the
calculations are carried out gravitational lensing of optical images cannot
probe the dilaton background.Comment: 9 pages, 1 figur
A bacterial toxin-antitoxin module is the origin of inter-bacterial and inter-kingdom effectors of Bartonella.
Host-targeting type IV secretion systems (T4SS) evolved from conjugative T4SS machineries that mediate interbacterial plasmid transfer. However, the origins of effectors secreted by these virulence devices have remained largely elusive. Previous work showed that some effectors exhibit homology to toxins of bacterial toxin-antitoxin modules, but the evolutionary trajectories underlying these ties had not been resolved. We previously reported that FicT toxins of FicTA toxin-antitoxin modules disrupt cellular DNA topology via their enzymatic FIC (filamentation induced by cAMP) domain. Intriguingly, the FIC domain of the FicT toxin VbhT of Bartonella schoenbuchensis is fused to a type IV secretion signal-the BID (Bep intracellular delivery) domain-similar to the Bartonella effector proteins (Beps) that are secreted into eukaryotic host cells via the host-targeting VirB T4SS. In this study, we show that the VbhT toxin is an interbacterial effector protein secreted via the conjugative Vbh T4SS that is closely related to the VirB T4SS and encoded by plasmid pVbh of B. schoenbuchensis. We therefore propose that the Vbh T4SS together with its effector VbhT represent an evolutionary missing link on a path that leads from a regular conjugation system and FicTA toxin-antitoxin modules to the VirB T4SS and the Beps. Intriguingly, phylogenetic analyses revealed that the fusion of FIC and BID domains has probably occurred independently in VbhT and the common ancestor of the Beps, suggesting parallel evolutionary paths. Moreover, several other examples of TA module toxins that are bona fide substrates of conjugative T4SS indicate that their recruitment as interbacterial effectors is prevalent and serves yet unknown biological functions in the context of bacterial conjugation. We propose that the adaptation for interbacterial transfer favors the exaptation of FicT and other TA module toxins as inter-kingdom effectors and may thus constitute an important stepping stone in the evolution of host-targeted effector proteins
Microcanonical statistics of black holes and bootstrap condition
The microcanonical statistics of the Schwarzschild black holes as well as the
Reissner-Nordstrm black holes are analyzed. In both cases we set
up the inequalities in the microcanonical density of states.
These are then used to show that the most probable configuration in the gases
of black holes is that one black hole acquires all of the mass and all of the
charge at high energy limit. Thus the black holes obey the statistical
bootstrap condition and, in contrast to the other investigation, we see that
U(1) charge does not break the bootstrap property.Comment: 16 pages. late
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