Network controller design for SONATA-a large-scale all-optical passive network

This paper describes the network architecture and provides a performance analysis of a passive optical network named SONATA, which has been proposed and demonstrated in the context of the European Union ACTS Program. In this nationwide all-optical network, end terminals access a single passive routing node via PONs using a TDMA/WDMA access scheme based on reservations. The centralized network controller runs resource allocation algorithms in order to avoid conflicts among end terminals. We formally define the resource allocation problem at the network controller, and show that, in general, it is NP-hard. We also provide simple heuristic algorithms to solve the problem. The analysis of the algorithms is performed both via analysis and simulation.     

Malta: housing and real estate, 1980–2005

Over the past two decades, private house ownership has expanded exponentially throughout Europe. Over the past decade, this has intensified with the desire and ability among wealthier northern Europeans to own second homes in sunnier climes. It has not only driven up house prices in pockets of Europe, but has also impacted on the social and cultural lives of local communities in ‘desirable locations’, having an adverse effect on the quality of the built environment. Lino Bianco describes the situation in Malta and how, after decades of largely uncontrolled development by real-estate investors, the government is taking stock and encouraging through investment in architectural education, and property legislation, the growth of an indigenous architecture that is contextual, sensitive and energy-conscious. Copyright © 2006 John Wiley & Sons, Ltd.     

Strong Band Gap Blueshift in Copper (I) Oxide Semiconductor via Bioinspired Route

Semiconductors have numerous applications in both science and technology. Several methods have been developed to engineer their band gap, which is one of the most important parameters of semiconductors. Here, it is shown that the incorporation of various amino acids into the crystal lattice of copper (I) oxide, akin to the way living organisms incorporate organic macromolecules into minerals during biomineralization, leads to significant shrinkage in the volume of the host unit cell and a strong blueshift in the band gap of up to ≈18%. In examining the potential location of the bio‐organic molecules within the inorganic host's lattice, a very good fit between the proposed model of incorporation and experimental findings is found. The bioinspired phenomenon of band gap widening is thought to be attributable to the void‐induced quantum confinement effect, even though observed in micrometer‐sized crystals. This hypothesis is supported by developing a tight‐binding model that is found to fit well with the experimental data. The outcome of this research could profoundly impact the fields of light‐emitting and spin‐based devices as well as opens up a new bioinspired route to tune the band gap of semiconductors.     

The recombination hotspot Chi is recognized by the translocating RecBCD enzyme as the single strand of DNA containing the sequence 5'-GCTGGTGG-3'

The RecBCD enzyme of Escherichia coli functions in the seemingly disparate roles of homologous recombination and the degradation of DNA. Which of these two roles it assumes is regulated by the 8-base recombination hotspot, Chi. Using double-stranded DNA substrates that are heteroduplex at the Chi locus we have established the determinants for Chi recognition. Our results show that an actively translocating RecBCD enzyme requires only the sequence information in the 5'-GCTGGTGG-3'-containing strand to recognize and to be regulated by Chi. Furthermore, the RecBCD enzyme can translocate through DNA heteroduplex bubbles as large as 22 bases, and still recognize a Chi sequence embedded in this region. This implies that recognition of Chi occurs following the unwinding of the DNA.     

Systemic Salmonella arizonae infections in patients with a deficiency of cell-mediated immunity. A report of 2 cases and a review of the literature

Systemic infections induced by Salmonella arizonae have been described in patients with underlying cell-mediated immunodeficiencies, usually resident in southern countries of U.S. and in Mexico. This peculiar geographic distribution is probably due to the ingestion of meat or drugs from rattlesnakes, that Salmonella arizonae colonize in the intestinal tract and that live in the above areas. In this article we describe two cases of systemic Salmonella arizonae infections, that represent, to our knowledge, the first report in European literature.     

Incremental scheduling algorithms for WDM/TDM networks with arbitrary tuning latencies

We focus on all-optical broadcast and select slotted WDM networks. Each network user is equipped with one tunable transmitter and one fixed receiver; full connectivity is achieved by tuning transmitters to all different wavelengths available in the optical spectrum. Tuning latencies are considered to be not negligible with respect to the slot time. A network controller allocates fixed size slots in a TDM/WDM frame according to requests issued by users via signalling procedures. User requests are accommodated in the frame incrementally, as soon as they are received by the network controller. Since we aim at an incremental solution, we impose a transparency constraint in the scheduling algorithm: new user requests may be accepted only without affecting existing allocations, otherwise they are refused. We propose a novel scheduling algorithm that may route some flows from source to destination through some intermediate nodes, following a multi-hop approach. A formal definition of an optimal transparent incremental scheduling algorithm is provided as an integer linear programming problem. The optimal incremental scheduling algorithm is NP-hard. Thus, a heuristic quasi-optimal scheduling algorithm is proposed, and its complexity is evaluated. Performance results show that significant benefits can be achieved with respect to traditional single-hop approaches and to other multi-hop approaches.     

Effects of hypothyroidism on brown adipose tissue adenylyl cyclase activity

Hypothyroidism profoundly reduces the capacity of brown adipose tissue (BAT) to generate cAMP in response to adrenergic stimulation. Evidence obtained with isolated brown adipocytes suggests a postreceptor defect that offsets the hypothyroidism-induced increase in beta3-adrenergic receptors. The goal of the present studies was to identify the defect in the cAMP generation pathway for which we studied cAMP generation in isolated cells and purified BAT membranes from normal and hypothyroid rats. Studies with adenosine deaminase and the adenosine receptor-1 agonist r-phenyl isopropyl adenosine (R-PIA) show that hypothyroid cells are not more sensitive to adenosine (same EC50) but more inhibited by high concentrations of R-PIA. Pretreatment with pertussis toxin reduced the gap in cAMP generation between eu- and hypothyroid cells and the inhibition mediated by R-PIA, but did not normalize the cAMP response to forskolin in hypothyroid cells. Although purified euthyroid BAT membranes increased cAMP production with GTP concentrations up to submillimolar range, to plateau or slightly decrease at higher levels, hypothyroid membranes were weakly stimulated by low concentrations of GTP and markedly inhibited (>50%) at concentrations > or = 10(-4) M. When assayed at 0.3 mM ATP and 1 microM GTP, hypothyroid membranes actually generated more cAMP in response to forskolin, but this was reversed when GTP concentration was 1 mM. Immunoblotting studies showed no significant effects of hypothyroidism on the abundance of G(alpha)i or Gbeta subunits, and ADP ribosylation of G(alpha)i was only 45% increased in hypothyroidism in contrast to a 2.5-fold increase in hypothyroid white adipose tissue membranes from the same rats. Hypothyroid membranes also exhibited different kinetics regarding ATP, with higher cAMP generation at submillimolar concentrations but less at >1 mM ATP. Actually, at ATP concentrations >0.6 mM, cAMP generation was markedly inhibited in hypothyroid membranes. Fixing the concentration of free Mg++ in these experiments indicates that most of the inhibition seen in hypothyroid membranes is caused by ATP, whereas euthyroid membranes are more sensitive to changes in free Mg++. Ca++ +/- calmodulin did not stimulate adenylyl cyclase (AC) activity. On the contrary, AC activity was inhibited by Ca++ in a concentration-dependent manner, by as low as 100 nM free Ca++, and to greater extent in hypo- than in euthyroid membranes (maximal inhibition 60 vs. 25-30%). Our results suggest that, functionally, hypothyroidism causes a change in the AC of BAT membranes consistent with a relative or absolute increase in the type VI AC (AC-VI). The effects on this AC of nucleotides, Ca++, and Mg++ at concentrations prevailing in the hypothyroid brown adipocyte are probably the major factor in the reduced capacity of these cells to generate cAMP. These results also open the possibility of a novel, differential effect of thyroid hormone on AC expression, and support the concept that thyroid hormone affects the adrenergic signal transduction pathways in a tissue-selective manner.     

The clinical outcome of preterm premature rupture of membranes in twin versus singleton pregnancies

Initial findings of panic disorder as an independent risk factor for suicidal ideation and behavior could not be replicated in studies with psychiatric patients. Instead, it was concluded that panic and anxiety disorders are risk factors when they co-occur with a primary mood disorder. In the present study, the effect of diagnostic comorbidity on rates of suicidality is analyzed on depressive inpatients treated at special depression wards. In a prospective follow-up study, suicidality and anxiety were assessed by means of a modified German version of the Diagnostic Interview Schedule (DIS). Patients with the symptom of panic attacks showed significantly elevated lifetime prevalence rates of suicidality in comparison with patients who did not report this additional symptom. For the follow-up period, however, there were no significant differences between these two groups. According to these results, the group of depressives with additional panic attacks is not more at risk for suicidal behavior, after being treated in an adequate manner.