Security of quantum cryptography using balanced homodyne detection

In this paper we investigate the security of a quantum cryptographic scheme which utilizes balanced homodyne detection and weak coherent pulse (WCP). The performance of the system is mainly characterized by the intensity of the WCP and postselected threshold. Two of the simplest intercept/resend eavesdropping attacks are analyzed. The secure key gain for a given loss is also discussed in terms of the pulse intensity and threshold.Comment: RevTeX4, 8pages, 7 figure

Full Quantum Analysis of Two-Photon Absorption Using Two-Photon Wavefunction: Comparison with One-Photon Absorption

For dissipation-free photon-photon interaction at the single photon level, we analyze one-photon transition and two-photon transition induced by photon pairs in three-level atoms using two-photon wavefunctions. We show that the two-photon absorption can be substantially enhanced by adjusting the time correlation of photon pairs. We study two typical cases: Gaussian wavefunction and rectangular wavefunction. In the latter, we find that under special conditions one-photon transition is completely suppressed while the high probability of two-photon transition is maintained.Comment: 6 pages, 4 figure

The role of cyclin synthesis, modification and destruction in the control of cell division

This paper reviews our current knowledge of the cyclins based on observations of the oocytes and eggs of sea urchins, clams and frogs. Cyclins are proteins found in all eukaryotes whose special property is rapid destruction at specific stages in the cell cycle. The cyclins fall into three families. A-type cyclins have been found in clams, flies and frogs. B-type cyclins have been found in clams, flies, frogs, sea urchins and fission yeast. A more distantly related family of three genes is found in Saccharomyces cerevisiae. B-type cyclins appear to be required for cells to enter mitosis, and their destruction is thought to be necessary for exit from mitosis. We describe evidence in support of these ideas, and describe various conditions under which cyclin destruction is delayed or deranged. We conclude with a discussion of the relationship between the cyclins and maturation- (or M phase-) promoting factor and some ideas on how the cyclins may work

Interfacial motion in flexo- and order-electric switching between nematic filled states

We consider a nematic liquid crystal, in coexistence with its isotropic phase, in contact with a substrate patterned with rectangular grooves. In such a system, the nematic phase may fill the grooves without the occurrence of complete wetting. There may exist multiple (meta)stable filled states, each characterised by the type of distortion (bend or splay) in each corner of the groove and by the shape of the nematic-isotropic interface, and additionally the plateaux that separate the grooves may be either dry or wet with a thin layer of nematic. Using numerical simulations, we analyse the dynamical response of the system to an externally- applied electric field, with the aim of identifying switching transitions between these filled states. We find that order-electric coupling between the fluid and the field provides a means of switching between states where the plateaux between grooves are dry and states where they are wet by a nematic layer, without affecting the configuration of the nematic within the groove. We find that flexoelectric coupling may change the nematic texture in the groove, provided that the flexoelectric coupling differentiates between the types of distortion at the corners of the substrate. We identify intermediate stages of the transitions, and the role played by the motion of the nematic-isotropic interface. We determine quantitatively the field magnitudes and orientations required to effect each type of transition.Comment: 14 pages, 12 fig

Alternative approach to electromagnetic field quantization in nonlinear and inhomogeneous media

A simple approach is proposed for the quantization of the electromagnetic field in nonlinear and inhomogeneous media. Given the dielectric function and nonlinear susceptibilities, the Hamiltonian of the electromagnetic field is determined completely by this quantization method. From Heisenberg's equations we derive Maxwell's equations for the field operators. When the nonlinearity goes to zero, this quantization method returns to the generalized canonical quantization procedure for linear inhomogeneous media [Phys. Rev. A, 43, 467, 1991]. The explicit Hamiltonians for the second-order and third-order nonlinear quasi-steady-state processes are obtained based on this quantization procedure.Comment: Corrections in references and introductio

The regulatory and transcriptional landscape associated with carbon utilization in a filamentous fungus.

Filamentous fungi, such as Neurospora crassa, are very efficient in deconstructing plant biomass by the secretion of an arsenal of plant cell wall-degrading enzymes, by remodeling metabolism to accommodate production of secreted enzymes, and by enabling transport and intracellular utilization of plant biomass components. Although a number of enzymes and transcriptional regulators involved in plant biomass utilization have been identified, how filamentous fungi sense and integrate nutritional information encoded in the plant cell wall into a regulatory hierarchy for optimal utilization of complex carbon sources is not understood. Here, we performed transcriptional profiling of N. crassa on 40 different carbon sources, including plant biomass, to provide data on how fungi sense simple to complex carbohydrates. From these data, we identified regulatory factors in N. crassa and characterized one (PDR-2) associated with pectin utilization and one with pectin/hemicellulose utilization (ARA-1). Using in vitro DNA affinity purification sequencing (DAP-seq), we identified direct targets of transcription factors involved in regulating genes encoding plant cell wall-degrading enzymes. In particular, our data clarified the role of the transcription factor VIB-1 in the regulation of genes encoding plant cell wall-degrading enzymes and nutrient scavenging and revealed a major role of the carbon catabolite repressor CRE-1 in regulating the expression of major facilitator transporter genes. These data contribute to a more complete understanding of cross talk between transcription factors and their target genes, which are involved in regulating nutrient sensing and plant biomass utilization on a global level

Modulation control and spectral shaping of optical fiber supercontinuum generation in the picosecond regime

Numerical simulations are used to study how fiber supercontinuum generation seeded by picosecond pulses can be actively controlled through the use of input pulse modulation. By carrying out multiple simulations in the presence of noise, we show how tailored supercontinuum Spectra with increased bandwidth and improved stability can be generated using an input envelope modulation of appropriate frequency and depth. The results are discussed in terms of the non-linear propagation dynamics and pump depletion.Comment: Aspects of this work were presented in Paper ThJ2 at OECC/ACOFT 2008, Sydney Australia 7-10 July (2008). Journal paper submitted for publication 30 July 200

Pulse-mode quantum projection synthesis: Effects of mode mismatch on optical state truncation and preparation

Quantum projection synthesis can be used for phase-probability-distribution measurement, optical-state truncation and preparation. The method relies on interfering optical lights, which is a major challenge in experiments performed by pulsed light sources. In the pulsed regime, the time frequency overlap of the interfering lights plays a crucial role on the efficiency of the method when they have different mode structures. In this paper, the pulsed mode projection synthesis is developed, the mode structure of interfering lights are characterized and the effect of this overlap (or mode match) on the fidelity of optical-state truncation and preparation is investigated. By introducing the positive-operator-valued measure (POVM) for the detection events in the scheme, the effect of mode mismatch between the photon-counting detectors and the incident lights are also presented.Comment: 11 pages, 4 figures, submitted to Phys. Rev.

Characteristics of transposable element exonization within human and mouse

Insertion of transposed elements within mammalian genes is thought to be an important contributor to mammalian evolution and speciation. Insertion of transposed elements into introns can lead to their activation as alternatively spliced cassette exons, an event called exonization. Elucidation of the evolutionary constraints that have shaped fixation of transposed elements within human and mouse protein coding genes and subsequent exonization is important for understanding of how the exonization process has affected transcriptome and proteome complexities. Here we show that exonization of transposed elements is biased towards the beginning of the coding sequence in both human and mouse genes. Analysis of single nucleotide polymorphisms (SNPs) revealed that exonization of transposed elements can be population-specific, implying that exonizations may enhance divergence and lead to speciation. SNP density analysis revealed differences between Alu and other transposed elements. Finally, we identified cases of primate-specific Alu elements that depend on RNA editing for their exonization. These results shed light on TE fixation and the exonization process within human and mouse genes.Comment: 11 pages, 4 figure

‘Lest we forget’*: a veteran and son share a ‘warfare tourism’ experience

Warfare tourism’ represents an increasingly significant dimension of contemporary tourism. This paper provides a fresh perspective on participation in ‘warfare tourism’ by investigating the behaviour and experiences of a living veteran and his son returning to two theatres of war in which the veteran had served in the Royal Navy during the Second World War. Active interviews with the two family members were used to gather rich data regarding the two extended trips, which had been funded by ‘Heroes Return’, to Australia in 2012 and Sri Lanka in 2013. The findings indicate that some of the facets of visiting the fallen at other dark tourism sites, such as empathetic identification and personal connection, are also very relevant to trips shared between the living. However, with the living these contribute to a powerful co-created experience in which ‘closer’ bonds between the travellers can be developed. Furthermore, whilst the experiences at times represented ‘bitter-sweet’ nostalgia for the veteran, they also provided the son with the opportunity to ‘look through his father’s eyes’ from both a past and current perspective. Given that there will be war veterans as long as conflicts exist, the results have valuable messages for all those dealing with veterans in the futur