Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

Effect of early treatment with angiotensin converting enzyme inhibition on segmental isobaric aortic stiffness and wall structure in adult spontaneously hypertensive rats

Early angiotensin converting enzyme (ACE) inhibition in spontaneously hypertensive rats (SHR) during a critical treatment window prevents the development of hypertension in adulthood. However the effects of such brief ACE inhibition on the structure and function of the aorta is still unknown. This study investigates the effects of ACE inhibition (perindopril, 3mg/kg/day, by gavage) in SHR (n=6) treated at pre- (6-10 weeks) and established (20-24 weeks of age) hypertensive phases. Hemodynamic parameters were recorded in anaesthetised rats over a wide range of blood pressure (BP) induced by infusion of phenylepherine and sodium nitroprusside 1 week after withdrawal of treatment. Vascular stiffness of the thoracic and abdominal aortic segments was calculated from beat-to-beat pulse wave velocity (PWV) measurements in vivo, by using 1.4F pressure catheters inserted in the carotid and femoral arteries and positioned at a known distance apart. Histological and morphological parameters of the segmental aortic media were measured. Heart rate remained steady in all treatment groups. Perindopril significantly decreased systolic BP measured using a tail-cuff method (-32%, P‹0.0001), anaesthetic mean arterial BP (-43%, P=0.0005), proximal (-31%, P=0.0009), distal pulse pressure (-27%, P=0.005), isobaric thoracic PWV (-19%, P=0.002) but not abdominal PWV. All effects in BP and PWV were non-significant in SHR treated late. Morphometric assessment of vascular structure showed that rats, when treated early, significantly decreases medial cross sectional area (-40%, P=0.0002) and wall thickness (-24%, P=0.001) of the abdominal aorta but not in the thoracic segment. ACE inhibition did not reduce the stiffness of the abdominal aorta despite concomitant decrease in both BP and vascular hypertrophy by markedly altering wall structure and content. This study shows that hypotrophy is not significant in the thoracic segment but stiffness was markedly reduced by ACE inhibition. This differential effect suggests the mechanism responsible for this change varies in different parts of the aorta. Effects of ACE inhibition on BP and arterial wall stiffness and structure were non-existent when given later in life.1 page(s

Persistent effect of early, brief angiotensin-converting enzyme inhibition on segmental pressure dependency of aortic stiffness in spontaneously hypertensive rats

Objective: The effect of brief, prehypertensive therapy by angiotensin-converting enzyme inhibition (ACEi) with perindopril on the structure and function of large arteries was studied in rats. Methods: Spontaneously hypertensive rats (SHR) received perindopril (3 mg/kg per day) between the ages of either 6 and 10 weeks (early) or 20 and 24 weeks (late) and compared with nonmedicated SHR and normotensive (Wistar–Kyoto) controls (n = 6 per group). Haemodynamic parameters and segmental aortic stiffness assessed by pulse wave velocity (PWV) were measured under urethane anaesthesia [1.3 g/kg, intraperitonealy (i.p.)] at 25 weeks. Aortic elastin and collagen content were determined by histomorphometry and calcium content by atomic absorption spectrophotometry. Results: Rats receiving brief, early perindopril therapy had lower tail-cuff SBP than nonmedicated SHR (121 ± 1 mmHg, 179 ± 5 mmHg, respectively, P < 0.05), reflected in lower thoracic and abdominal aortic pulse pressures. Aortic pulse pressure amplification was lower with early perindopril treatment (early treated 10 ± 5%, nonmedicated 20 ± 10%, P < 0.05). No blood pressure (BP) differences were observed between late treated and nonmedicated SHR. Isobaric thoracic PWV was lower when treated early but not later in life. Treatment did not alter abdominal PWV. Early treatment was associated with reduction in total aortic calcification (48%, P < 0.001) and reduction in medial cross-sectional area (40%, P < 0.05) of abdominal aorta compared with nonmedicated rats. Treatment increased the wall thickness/diameter ratio, but only early treated rats had a 46% higher elastin/collagen ratio compared with SHR controls. Conclusions: Early but not late brief ACEi decreased arterial pressure and isobaric wall stiffness in SHR. This was associated with marked alteration of wall structure and the effects persisted after cessation of early treatment. The structural mechanisms responsible for this change varied segmentally along the aortic trunk.9 page(s

Heart rate dependence of aortic pulse wave velocity at different arterial pressures in rats

Arterial stiffness, as measured by aortic pulse wave velocity (PWV), is an independent marker of cardiovascular disease and events in both healthy and diseased populations. Although some cardiovascular risk factors, such as age and blood pressure, show a strong association with PWV, the association between heart rate (HR) and PWV is not firmly established. Furthermore, this association has not been investigated at different arterial blood pressures. To study effects of HR on aortic PWV at different mean arterial pressures (MAPs), adult (12 weeks; n=7), male, anesthetized Sprague-Dawley rats were randomly paced at HRs of between 300 and 450 bpm, at 50-bpm steps. At each pacing step, aortic PWV was measured across a physiological MAP range of 60 to 150 mmHg by infusing sodium nitroprusside and phenylephrine. When compared at the same MAP, increases in HR resulted in significant increases in PWV at all of the MAPs >80 mmHg (ANOVA, P<0.05), with the greatest significant change of 6.03±0.93% observed in the range 110 to 130 mmHg. The positive significant association between HR and PWV remained when PWV was adjusted for MAP (ANOVA, P<0.001). These results indicate that HR dependency of PWV is different at higher pressures than at lower pressures and that HR may be a confounding factor that should be taken into consideration when performing analysis based on PWV measurements.6 page(s

The institutional legacy and the development of an Australian national innovation system

Institutions are the rules of the game that help to shape the long-term historical development of societies. They mediate human interaction and can be more or less formal (or tangible) in nature ranging from systems of government to common modes of behaviour. Most formal institutions can be distinguished as economic, social, political or cultural in nature although such distinctions are more difficult to make for informal institutions. What is certain is the pervasive impact of all types of institutions on a country’s multifaceted development. Thus, economic performance may be shaped as much by a nation’s legal system as by its trade policy