Climatic control on the peak discharge of glacier outburst floods

Lakes impounded by natural ice dams occur in many glacier regions. Their sudden emptying along subglacial paths can unleash similar to 1 km(3) of floodwater, but predicting the peak discharge of these subglacial outburst floods ('jokulhlaups') is notoriously difficult. To study how environmental factors control jokulhlaup magnitude, we use thermo- mechanical modelling to interpret a 40- year flood record from Merzbacher Lake in the Tian Shan. We show that the mean air temperature during each flood modulates its peak discharge, by influencing both the rate of meltwater input to the lake as it drains, and the lake- water temperature. The flood devastation potential thus depends sensitively on weather, and this dependence explains how regional climatic warming drives the rising trend of peak discharges in our dataset. For other subaerial ice- dammed lakes worldwide, regional warming will also promote higher- impact jokulhlaups by raising the likelihood of warm weather during their occurrence, unless other factors reduce lake volumes at flood initiation to outweigh this effect

Non-stationary de Sitter cosmological models

In this note it is proposed a class of non-stationary de Sitter, rotating and non-rotating, solutions of Einstein's field equations with a cosmological term of variable function.Comment: 11 pages, Latex. International Journal of Modern Physics D (accepted for publication

[CI], [CII] and CO emission lines as a probe for alpha variations at low and high redshifts

The offsets between the radial velocities of the rotational transitions of carbon monoxide and the fine structure transitions of neutral and singly ionized carbon are used to test the hypothetical variation of the fine structure constant, alpha. From the analysis of the [CI] and [CII] fine structure lines and low J rotational lines of 12CO and 13CO, emitted by the dark cloud L1599B in the Milky Way disk, we find no evidence for fractional changes in alpha at the level of |$\Delta \alpha/\alpha$| < 3*10^-7. For the neighbour galaxy M33 a stringent limit on Delta alpha/alpha is set from observations of three HII zones in [CII] and CO emission lines: |$\Delta \alpha/\alpha$| < 4*10^-7. Five systems over the redshift interval z = 5.7-6.4, showing CO J=6-5, J=7-6 and [CII] emission, yield a limit on |$\Delta \alpha/\alpha$| < 1.3*10^-5. Thus, a combination of the [CI], [CII], and CO emission lines turns out to be a powerful tool for probing the stability of the fundamental physical constants over a wide range of redshifts not accessible to optical spectral measurements.Comment: 10 pages, 3 figures, 5 tables. Accepted for publication in MNRA

Turbo Detection of Space-time Trellis-Coded Constant Bit Rate Vector-Quantised Videophone System using Reversible Variable-Length Codes, Convolutional Codes and Turbo Codes

In this treatise we characterise the achievable performance of a proprietary video transmission system, which employs a Constant Bit Rate (CBR) video codec that is concatenated with one of three error correction codecs, namely a Reversible Variable-Length Code (RVLC), a Convolutional Code (CC) or a convolutional-based Turbo Code (TC). In our investigations, the CBR video codec was invoked in conjunction with Space-Time Trellis Coding (STTC) designed for transmission over a dispersive Rayleigh fading channel. At the receiver, the channel equaliser, the STTC decoder and the RVLC, CC or TC decoder, as appropriate, employ the Max-Log Maximum A-Posteriori (MAP) algorithm and their operations are performed in an iterative 'turbo-detection' fashion. The systems were designed for maintaining similar error-free video reconstruction qualities, which were found to be subjectively pleasing at a Peak Signal to Noise Ratio (PSNR) of 30.6~dB, at a similar decoding complexity per decoding iteration. These design criteria were achieved by employing differing transmission rates, with the CC- and TC-based systems having a 22% higher bandwidth requirement. The results demonstrated that the TC-, RVLC- and CC-based systems achieve acceptable subjective reconstructed video quality associated with an average PSNR in excess of 30~dB for $E_b/N_0$ values above 4.6~dB, 6.4~dB and 7.7~dB, respectively. The design choice between the TC- and RVLC-based systems constitutes a trade-off between the increased error resilience of the TC-based scheme and the reduced bandwidth requirement of the RVLC-based scheme

On the variable-charged black holes embedded into de Sitter space: Hawking's radiation

In this paper we study the Hawking evaporation of masses of variable-charged Reissner-Nordstrom and Kerr-Newman, black holes embedded into the de Sitter universe by considering the charge to be function of radial coordinate of the spherically symmetric metric.Comment: LaTex, p. 2

Charged black holes in Vaidya backgrounds: Hawking's Radiation

In this paper we propose a class of embedded solutions of Einstein's field equations describing non-rotating Reissner-Nordstrom-Vaidya and rotating Kerr-Newman-Vaidya black holes.Comment: 30 pages, latex file, no figure

A Chemical Survey of the Batang Belungkung River and the Gombak River

A chemical survey of water quality in the Batang Belungkung River and the Gombak River was conducted to assess the degree of pollution due to the continuing discharge of rubber and domestic wastes. Levels of dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), nutrients (phosphorus and nitrogen), solid and trace elements (sodium, potassium, calcium and magnesium) were monitored sequentially downriver. The Batang Belungkung River was found to be severely polluted with anaerobic conditions existing downriver. The upper region of the Gombak River was relatively unpolluted while the lower region of the Gombak River was found to be severely polluted. An increase of approximately fourteen-fold was found in the oxygen demand in the lower region of the Gombak River over the ten year period from 1968/69 to 1978/79

Validation of the English and Chinese versions of the Quick-FLIC quality of life questionnaire.

A useful measure of quality of life should be easy and quick to complete. Recently, we reported the development and validation of a shortened Chinese version of the Functional Living Index-Cancer (FLIC), which we called the Quick-FLIC. In the present study of 327 English-speaking and 221 Chinese-speaking cancer patients, we validated the English version of the Quick-FLIC and further assessed the Chinese version. The 11 Quick-FLIC items were administered alongside the 11 remaining items of the full FLIC, but there appeared to be little context effect. Validity of the English version of the Quick-FLIC was attested by its strong correlation with two other measures of quality of life, and its ability to detect differences between patients with different performance status and treatment status (each P<0.001). Its internal consistency (alpha=0.86) and test-retest reliability (intraclass correlation=0.76) were also satisfactory. The measure was responsive to changes in performance status (P<0.001). The Chinese version showed similar characteristics. The Quick-FLIC behaved in ways that are highly comparable with the FLIC, even though the Quick-FLIC comprised only 11 items whereas the FLIC comprised 22. Further research is required to see whether the use of shorter instruments can improve data quality and response rates, but the fact that shorter instruments place less burden on the patients is itself inherently important

Disjoint difference families and their applications

Difference sets and their generalisations to difference families arise from the study of designs and many other applications. Here we give a brief survey of some of these applications, noting in particular the diverse definitions of difference families and the variations in priorities in constructions. We propose a definition of disjoint difference families that encompasses these variations and allows a comparison of the similarities and disparities. We then focus on two constructions of disjoint difference families arising from frequency hopping sequences and showed that they are in fact the same. We conclude with a discussion of the notion of equivalence for frequency hopping sequences and for disjoint difference families