Tuning energy transfer in switchable donor-acceptor systems

The synthesis and characterisation of a coumarin-dithienylcyclopentene-coumarin symmetric triad (CSC) and a perylene bisimide-dithienylcyclopentene-coumarin asymmetric triad (PSC) are reported. In both triads the switching function of the photochromic dithienylcyclopentene unit is retained. For CSC an overall 50% quenching of the coumarin fluorescence is observed upon ring-closure of the dithienylcyclopentene component, which, taken together with the low PSS (<70%), indicates that energy transfer quenching of the coumarin component by the dithienylcyclopentene in the closed state is efficient. Upon ring opening of the dithienylcyclopentene unit the coumarin emission is restored fully. The PSC triad shows efficient energy transfer from the coumarin to the perylene bisimide unit when the dithienylcyclopentene unit is in the open state. When the dithienylcyclopentene is in the closed ( PSS) state a 60% decrease in sensitized perylene bisimide emission intensity is observed due to competitive quenching of the coumarin excited state and partial quenching of the perylene excited state by the closed dithienylcyclopentene unit. This modulation of energy transfer is reversible over several cycles for both the symmetric and asymmetric tri-component systems

Beyond crime statistics: the construction and application of a criminogenity monitor in Amsterdam

Criminologists have devoted a great deal of attention to risk factors - also called criminogenic factors - leading to criminal offending. This paper presents a criminogenity monitor which includes 19 risk factors that underlie crime. These factors do not themselves cause criminal behaviour; rather, they must be seen as signals that crimes may be committed. After discussing how the criminogenity monitor was constructed, we apply the risk factors we examined to the situation in Amsterdam, capital city of the Netherlands. The monitor is intended to function particularly as an instrument to rationalise policy-makers' work in targeting and preventing symptoms of crime at three geographical levels: the entire city, its boroughs and its neighbourhoods. © 2012 The Author(s)

Burgerinitiatieven in tijden van crisis: Onderzoek naar de factoren die de bestendigheid van burgerinitiatieven beïnvloeden

In the Netherlands, citizens’ initiatives have received a lot of praise and are increasingly made responsible for providing public services. If they are to fulfil this role, they must be able to weather a crisis, as during a crisis public services should remain reliable. Literature on the durability of citizens’ initiatives suggests that large initiatives, with a close-knit core group and strong government support are the most durable. However, our research indicates that this was not the case during the COVID-19 crisis. Flexibility and freedom to function independently from the municipal government were found to be more decisive for durability. This suggests that despite public value of citizens’ initiatives, they cannot be expected to take much responsibility for durable public service provision

Citizens' Initiatives in Times of Crisis:an investigation into the factors that influence the durability of citizens’ initiatives.

In the Netherlands, citizens’ initiatives have received a lot of praise and are increasingly made responsible for providing public services. If they are to fulfil this role, they must be able to weather a crisis, as during a crisis public services should remain reliable. Literature on the durability of citizens’ initiatives suggests that large initiatives, with a close-knit core group and strong government support are the most durable. However, our research indicates that this was not the case during the COVID-19 crisis. Flexibility and freedom to function independently from the municipal government were found to be more decisive for durability. This suggests that despite public value of citizens’ initiatives, they cannot be expected to take much responsibility for durable public service provision

Equally high efficacy of 4, 7 and 10-day triple therapies to eradicate Helicobacter pylori infection in patients with ulcer disease

BACKGROUND: In patients with ulcer disease the optimal dose and duration of Helicobacter pylori treatment containing omeprazole (O), metronidazole (M) and clarithromycin (C) has yet to be established. The efficacy might be influenced by metronidazole- and clarithromycin-resistance. AIM: To study the effect of duration of OMC treatment on its efficacy and influence of metronidazole-resistance and clarithromycin-resistance on the optimal duration. MATERIALS AND METHODS: Ulcer patients (n=76) were randomized to three double-blind treatments of 10 days: OMC 4 consisted of 4 days b.d. 20 mg omeprazole, 400 mg metronidazole and 250 mg clarithromycin switched over to 6 days b.d. 20 mg omeprazole and placebo antibiotics (n=27); OMC 7 consisted of 7 days b.d. omeprazole 20 mg, metronidazole 400 mg and clarithromycin 250 mg and 3 days b.d. omeprazole 20 mg and placebo antibiotics (n=25); OMC 10 consisted of 10 days b.d. omeprazole 20 mg, metronidazole 400 mg and clarithromycin 250 mg (n=24). H. pylori was assessed by biopsies for culture and histology pre- and 4-6 weeks after OMC therapy. Metronidazole-resistance and clarithromycin-resistance were assessed by the E-test. RESULTS: Intention-to-treat-eradication rates were: OMC 4, 96%; OMC 7, 92%; and OMC 10, 96% (N.S.). All of the three per protocol eradication rates were 100% (95% CI: 85.2-100). Of 75 isolates, 16 were metronidazole-resistant and one was clarithromycin-resistant. CONCLUSION: In H. pylori-positive ulcer patients, OMC 4 is highly efficacious and as effective as OMC 7 and OMC 10. No influence of metronidazole-resistance or clarithromycin-resistance was observe

Meta-analysis: the influence of pre-treatment with a proton pump inhibitor on Helicobacter pylori eradication.

Contains fulltext : 48800.pdf (publisher's version ) (Closed access)BACKGROUND: There is much debate about the influence of pre-treatment with a proton pump inhibitor on Helicobacter pylori eradication. The few studies investigating the influence of pre-treatment on triple and quadruple therapies did not find differences in eradication rates. However, the high eradication rates make it difficult to study factors associated with therapy failure in small populations. In order to overcome this problem we performed a meta-analysis. METHODS: The literature was searched in order to identify randomized clinical trials comparing modern triple/quadruple therapies for H. pylori eradication without pre-treatment with a proton pump inhibitor with exactly the same regimen with pre-treatment. The overall risk difference (with - without pre-treatment) was calculated by pooling the risk differences of the individual studies weighted by the inverse of their variances. RESULTS: Nine studies, investigating a total of 773 patients, were identified. There was considerable variation regarding therapy regimen and duration. Pooled eradication rates were 81.3% (312 of 384) for patients with pre-treatment and 81.2% (316 of 389) for patients without pre-treatment. The (weighted) overall risk difference was 0.1% (95% CI: -5%; 5%). CONCLUSION: Pre-treatment with a proton pump inhibitor does not influence H. pylori eradication