282 research outputs found
The 20-60-20 Rule
In this paper we discuss an empirical phenomena known as the 20-60-20 rule.
It says that if we split the population into three groups, according to some
arbitrary benchmark criterion, then this particular ratio implies some sort of
balance. From practical point of view, this feature often leads to efficient
management or control. We provide a mathematical illustration, justifying the
occurrence of this rule in many real world situations. We show that for any
population, which could be described using multivariate normal vector, this
fixed ratio leads to a global equilibrium state, when dispersion and linear
dependance measurement is considered
A note on conditional covariance matrices for elliptical distributions
In this short note we provide an analytical formula for the conditional
covariance matrices of the elliptically distributed random vectors, when the
conditioning is based on the values of any linear combination of the marginal
random variables. We show that one could introduce the univariate invariant
depending solely on the conditioning set, which greatly simplifies the
calculations. As an application, we show that one could define uniquely defined
quantile-based sets on which conditional covariance matrices must be equal to
each other if only the vector is multivariate normal. The similar results are
obtained for conditional correlation matrices of the general elliptic case
Cyrenaican coinage from the beginning of Roman rule : new evidence from Ptolemais
Warsaw University Institute of Archaeology excavations at the so-called Villa with a View in Ptolemais, have contributed significantly to knowledge of town history and development. Numismatics is one field in which substantial verification as well as new evidence has been collected.
Current finds by the Polish mission, have helped to rethink Cyrenaican coinage in both the Hellenistic and Roman periods, especially with regard to local issues from the beginning of Imperial rule, which are presented in the article.Agnieszka Uziębł
Negative curvature fibre optics for delivery of high-peak power light for manufacturing applications
This thesis covers investigations into high peak power short (nanosecond) and ultrashort
(picosecond and femtosecond) pulse delivery through novel hollow-core
microstructured silica fibres - the Negative Curvature Fibre (NCF) and the Free
Boundary Anti-Resonant Fibre (FBARF) for manufacturing applications. Both types of
fibres provide light guidance in the NIR and green spectral regions via the Anti-
Resonant Reflecting Optical Waveguiding (ARROW) mechanism.
NCFs exhibit extremely low attenuations of 0.04 dB/m and 0.15 dB/m at 1030
nm and 532 nm respectively, not achievable with photonic bandap hollow-core fibres.
These fibres have been demonstrated to deliver NIR and green picosecond pulses with
peak powers at the level of 15 MW and 5 MW respectively, which significantly exceeds
the capabilities of commercially available singlemode fibres. Optimised NCFs for
transmission in both spectral regimes provide singlemode, high quality output and
maintain the spectral and temporal properties of the original laser pulse. Furthermore,
these fibres exhibit a low sensitivity to bending with useful bend diameters ≥ 5 cm,
which is sufficient for most beam delivery applications. This was further improved by
developing and introducing a dynamic fibre delivered power stabilisation system which
enables efficient compensations of bend-induced power fluctuations.
Practical implementation of NCF delivered pulses in manufacturing applications
has been demonstrated in the precision micro-machining of metals, crack-free micromilling
of fused silica and waveguide writing in borosilicate glass.
The FBARF structure is a modification of the NCF design aimed for an
improvement in energy handling capacity, light confinement and further reduction of
bending loss. However, the fibres reported in this thesis (fabricated for guidance at 1
μm and green wavelengths) are preliminary designs, and so their full potential e.g. their
energy handling capacities could not be fully established. Nevertheless, initial tests
performed within this work indicated that further development of this fibre design
should result in a reduction of the intrinsic attenuation and bend loss to a level
comparable with the NCFs while increasing the optical damage threshold
Use of cryotherapy in different diseases
Physiotherapy section - physicotherapy successfully applies frequent cryotherapy treatments in many different diseases. The paper presents a review of the literature on the basis of review papers as well as research papers from reputable scientific journals, which have been published over the last few years
Use of kinesiology taping in different diseases
Kinesiology taping, called in Poland more and more often dynamic plastering is a method with a very wide application. More and more often this method is noticed among patients. Currently, many studies have been conducted, in which the effectiveness of therapy with the use of tapes for kinesiology taping has been proven. What is more, no harmful effects of this form of therapy have been found. In addition, there is more and more research showing the effectiveness of cathodiology taping as a form of supporting the effects of the main therapy. The paper was written on the basis of review articles and research papers presented in reputable Polish magazines dealing with physiotherapy
Postural defects - kyphosis, lordosis, sway back, flat back. Part two
Posture defects are a serious social problem. It is very important to be able to distinguish between postural defects. A part of the second part of the paper presents a description of kyphosis, lordosis, sway back and flat back
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