67 research outputs found
Fermionic T-duality in fermionic double space
In this article we offer the interpretation of the fermionic T-duality of the
type II superstring theory in double space. We generalize the idea of double
space doubling the fermionic sector of the superspace. In such doubled space
fermionic T-duality is represented as permutation of the fermionic coordinates
and with the corresponding fermionic T-dual
ones, and , respectively. Demanding
that T-dual transformation law has the same form as inital one, we obtain the
known form of the fermionic T-dual NS-R i R-R background fields. Fermionic
T-dual NS-NS background fields are obtained under some assumptions. We conclude
that only symmetric part of R-R field strength and symmetric part of its
fermionic T-dual contribute to the fermionic T-duality transformation of
dilaton field and analyze the dilaton field in fermionic double space. As a
model we use the ghost free action of type II superstring in pure spinor
formulation in approximation of constant background fields up to the quadratic
terms.Comment: Four paragraphs in the Introduction added in order to better motivate
the subject, explained the choice of action (detailed derivation
Canonical approach to the closed string noncommutativity
We consider the closed string moving in the weakly curved background and its
totally T-dualized background. Using T-duality transformation laws, we find the
structure of the Poisson brackets in the T-dual space corresponding to the
fundamental Poisson brackets in the original theory. From this structure we
obtain that the commutative original theory is equivalent to the
non-commutative T-dual theory, whose Poisson brackets are proportional to the
background fluxes times winding and momenta numbers. The non-commutative theory
of the present article is more nongeometrical then T-folds and in the case of
three space-time dimensions corresponds to the nongeometric space-time with
-flux.Comment: We add the Sec. 4. where we compared our results with previous ones.
We also improved Abstract, Introduction and Conclusion as described above. In
addition, we corrected all typos and grammatical errors we notice
Atmospheric dispersion and the implications for phase calibration
The success of any ALMA phase-calibration strategy, which incorporates phase
transfer, depends on a good understanding of how the atmospheric path delay
changes with frequency (e.g. Holdaway & Pardo 2001). We explore how the wet
dispersive path delay varies for realistic atmospheric conditions at the ALMA
site using the ATM transmission code. We find the wet dispersive path delay
becomes a significant fraction (>5 per cent) of the non-dispersive delay for
the high-frequency ALMA bands (>160 GHz, Bands 5 to 10). Additionally, the
variation in dispersive path delay across ALMA's 4-GHz contiguous bandwidth is
not significant except in Bands 9 and 10. The ratio of dispersive path delay to
total column of water vapour does not vary significantly for typical amounts of
water vapour, water vapour scale heights and ground pressures above Chajnantor.
However, the temperature profile and particularly the ground-level temperature
are more important. Given the likely constraints from ALMA's ancillary
calibration devices, the uncertainty on the dispersive-path scaling will be
around 2 per cent in the worst case and should contribute about 1 per cent
overall to the wet path fluctuations at the highest frequencies.Comment: 13 pages, 10 figures, ALMA Memo 59
Morphometric analysis of collagen and inflammatory cells in periodontal disease
© 2015, Institut za Vojnomedicinske Naucne Informacije/Documentaciju. All rights reserved. Background/Aim. Periodontal disease affects gingival tissue and supporting apparatus of the teeth leading to its decay. The aim of this study was to highlight and precisely determine his-tological changes in the gum tissue. Methods. Gingival biopsy samples from 53 healthy and parodontopathy-affected patients were used. Clinical staging of the disease was performed. Tissue specimens were fixed and routinely processed. Sections, 5 μm thin, were stained with hematoxylin and eosin, histochemical Van-Gieson for the collagen content, Spicer method for mast-cells and immunochemical method with anti-CD68 and anti-CD38 for the labelling of the macrophages and plasma-cells. Morphometric analysis was performed by a M42 test system. Results. While the disease advanced, collagen and fibroblast volume density decreased almost twice in the severe cases compared to the control ones, but a significant variation was observed within the investigated groups. The mast-cell number increased nearly two times, while the macrophage content was up to three times higher in severe parodontopathy than in healthy gingival tissue. However, the relative proportion of the-se cells stayed around 6% in all cases. Plasma-cells had the most prominent increase in the number (over 8 times) com-pared to the control, but again, a variation within investigated groups was very high. Conclusion. Gingival tissue destruction caused by inflammatory process leads to significant changes in collagen density and population of resident connective tissue cells. Although inflammatory cells dominated with the disease advancing, a high variation within the same investigated groups suggests fluctuation of the pathological process
LTE AND WIFI CO-EXISTENCE IN 5 GHZ UNLICENSED BAND
Since the future mobile networks will require significantly higher data throughput, and the Long-Term Evolution (LTE) licensed bands are already occupied, the frequency band extension and the data rate increase may be achieved by using some of the available unlicensed bands. The most appropriate unlicensed band for this purpose lies in 5 GHz frequency range. However, this unlicensed band is already occupied by WiFi networks and a special attention has to be paid to coordinate these two different networks in the shared spectrum usage. Therefore, this paper considers the shared access co-existence in 5 GHz unlicensed band between uncoordinated LTE and WiFi networks. More precisely, it considers the influence of the LTE downlink transmission on the performance of the WiFi networks. The experimental results show that the LTE significantly degrades the WiFi network performance, which means that some of the coordination algorithms have to be employed
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