Cyclicity in ℓp\ell^p spaces and zero sets of the Fourier transforms

We study the cyclicity of vectors $u$ in $\ell^p(\mathbb{Z})$. It is known that a vector $u$ is cyclic in $\ell^2(\mathbb{Z})$ if and only if the zero set, $\mathcal{Z}(\widehat{u})$, of its Fourier transform, $\widehat{u}$, has Lebesgue measure zero and $\log |\widehat{u}| \not \in L^1(\mathbb{T})$, where $\mathbb{T}$ is the unit circle. Here we show that, unlike $\ell^2(\mathbb{Z})$, there is no characterization of the cyclicity of $u$ in $\ell^p(\mathbb{Z})$, $1<p<2$, in terms of $\mathcal{Z}(\widehat{u})$ and the divergence of the integral $\int\_\mathbb{T} \log |\widehat{u}|$. Moreover we give both necessary conditions and sufficient conditions for $u$ to be cyclic in $\ell^p(\mathbb{Z})$, $1<p<2$.Comment: Australian Journal of Mathematical Analysis and Applications, Austral Internet Publishing, A Para{\^i}tr

A multi-step assembly process: drawing, flanging and hemming of metallic sheets

International audienceThis paper presents hemming tests on complex geometries, combining curved surfaces and radii of curvature in the plane. The samples are firstly prestrained in order to obtain a strain history prior to flanging and hemming. The choice of the sample geome-tries as well as prior plastic strains is based on a survey of current geometries hemmed in automotive doors. A device has been designed to hem these samples both by classical and roll-hemming processes and to allow a comparison between both technologies. Roll-in, which characterizes the change of geometry of the hemmed zone between flanging and hemming, and loads are obtained during this multistep process. Results show that roll-in observed in roll-hemming is lower than in classical hemming and that its evolution greatly differs between the two processes. The analysis of the results on different samples shows that it is difficult to establish rules on the variation of other parameters in such a complex multistep process and that it requires an intensive use of numerical simulation

Occurrence and numerical prediction of surface defects during flanging of metallic sheets

International audienceSurface defects can develop on automotive exterior panels after drawing and flanging steps, during springback and may alter significantly the vehicle quality. These defects are characterized by a small depth below 0.5 mm and are then difficult to detect numerically. This study focuses on the surface defects for two parts: an industrial upper corner of a front door and a L-shaped part designed on purpose to reproduce at a small scale surface defects that occur after flanging. Dimensions of these defects are measured from profiles obtained either with a non-contacting method or a tridimensional measuring machine. Numerical simulations of the processes are performed with the commercial codes PamStamp2G or Abaqus and deformed meshes are analyzed in the same way as the experimental data. There is a good correlation between experiments and simulations concerning the spatial position of the defect and their dimensions. Moreover, a buckling analysis during springback is performed for the L-shaped part, showing that the position of the defect corresponds to one of the buckling mode

Influence of prestrain on the numerical simulation of the roller hemming process

International audienceThis study focuses on the numerical simulation of roller hemming of an aluminium alloy sample with a curved geometry; this non-planar geometry is obtained by a prestrain procedure similar to deep drawing process. Material characterization was performed through tensile and simple shear tests at different orientations on the sheet plane. The influence of considering the Bauschinger effect, anisotropy, and the strain history on the final geometry was studied. A specific laboratory device for roller hemming was designed to forward an experimental database. The numerical simulation of the roller hemming of these samples is presented here, as well as the correlation between the calculations and the experimental tests, notably the roll-in value and the prediction of wrinkling

Public subsidies have supported the development of electric trawling in Europe

In the 2000s, the Dutch beam trawl fleet was in chronic deficit and under pressure to reduce its environmental impact. Instead of converting to selective fishing gears, it successfully lobbied the European Commission with the support of public authorities and scientists to obtain derogations against formal scientific advice to practice a prohibited technique: electric trawling. Since then, electric trawling has expanded beyond regulatory threshold: 84 large trawlers now catch the vast majority of the Dutch flatfish quota, causing detrimental socio-environmental impacts. To assess whether the European Union's fisheries policies fulfilled legal objectives and implemented the 2030 Agenda, it appeared crucial to quantify how much public financial aid had been provided to the Dutch fishing sector for its conversion to electric trawling. The financial information enabling this evaluation was first concealed but was eventually obtained. We show that the institutional opacity surrounding electric trawling was not serendipitous and has served to dissimulate allocations of public monies to a prohibited fishing method (otter trawl), illegal licenses, and falsely ‘scientific’ fishing. In breach of EU laws, 20.8 million EUR of structural funds have so far been granted to this sector in the form of direct subsidies, i.e. over 30 times the amount acknowledged by the fishing industry. The findings presented here lift part of the veil surrounding electric trawling, but the complete reconstruction of the impacts of this fishing method can only be done when decision-makers and scientists disclose all data in full transparency and become the warrants of the public interestS

Determination of the threshold of cardiac troponin I associated with an adverse postoperative outcome after cardiac surgery: a comparative study between coronary artery bypass graft, valve surgery, and combined cardiac surgery

ABSTRACT: BACKGROUND: To compare postoperative cardiac troponin I (cTnI) release and the thresholds of cTnI that predict adverse outcome after elective coronary artery bypass graft (CABG), valve, and combined cardiac surgery. METHODS: Six hundred and seventy five adult patients undergoing conventional cardiac surgery with cardiopulmonary bypass were retrospectively analyzed. Patients in the CABG (n=225) and valve surgery groups (n=225) were selected after matching (age, sex) with those in the combined surgery group (n=225). cTnI was measured preoperatively and 24 h after the end of surgery. The main endpoint was a severe postoperative cardiac event (sustained ventricular arrhythmias requiring treatment, need for inotropic support or intra-aortic balloon pump for at least 24 h, postoperative myocardial infarction) and/or death. Data are medians and odds ratio [95% confidence interval]. RESULTS: Postoperative cTnI levels were significantly different among the three groups (Combined 11.0 [9.5-13.1] vs. CABG 5.2 [4.7-5.7] and Valve 7.8 [7.6-8.0] ng.mL-1, respectively, P&lt;0.05). The thresholds of cTnI predicting severe cardiac event and/or death were also significantly different among the three groups (Combined 11.8 [11.5-14.8] vs. CABG 7.8 [6.7-8.8] and Valve 9.3 [8.0-14.0] ng.mL-1 respectively, P&lt;0.05 level). An elevated cTnI above the threshold in each group was significantly associated with severe cardiac event and/or death (odds ratio, 4.33 [2.82-6.64]). CONCLUSIONS: The magnitude of postoperative cTnI release is related to the type of cardiac surgical procedure. Different thresholds of cTnI must be considered according to the procedure type to predict early an adverse postoperative outcom

Advancing tuna catch allocation negotiations: an analysis of sovereign rights and fisheries access arrangements

Regional fisheries management organisations (RFMOs) determine conservation measures for transboundary fsheries resources. They are also a forum for collective action toward the management of marine resources. One of the most complex and controversial aspects of this process is the allocation of catches between RFMO members. There are a variety of processes that can be used for catch allocation. In recent years, there has been a trend in some RFMOs towards establishing a system of criteria or indicators to determine the volume or percentage of catch that should be allocated to each RFMO member. Establishing such a system is challenging and the position of countries negotiating at RFMOs is also shaped by fisheries access arrangements. The debate on allocation has been ongoing at the Indian Ocean Tuna Commission for more than a decade, where one key point of disagreement is the treatment of historical catch taken in the waters of a coastal State. On the one hand, coastal states claim that catches historically taken in their exclusive economic zones (EEZ) should be attributed to them based on their sovereign rights over living resources. On the other, some fishing countries from outside the region claim catch history based on fishing conducted in the coastal State’s waters pursuant to access agreements. We analysed UNCLOS articles, publicly available fisheries access agreements, and national legislation to unpack the linkage between fisheries access arrangements and catch allocation discussions, and we also explored examples from other regions and RFMOs. We point out that the sovereign rights of coastal states over their EEZ provide a strong basis for allocation negotiations. In the absence of specific agreements to the contrary, any catch history that arises from foreign vessels fishing inside the EEZ should be attributed to the coastal State. We also argue that it is time for members of RFMOs—and especially of the Indian Ocean Tuna Commission—to move beyond the historical catch debate. They need to resolve their differences or consider other ways to allocate participatory rights in shared fisheries

Weak regulation of distant water fleets puts rented fishery in jeopardy; a critical analysis of fisheries partnership agreements in Madagascar

Madagascar is the world, fourth biggest island, and one of the world‚ poorest countries. Given its severe poverty, Madagascar has no large-scale domestic fleet. Consequently, it is required by the United Nations Convention on the Law of the Sea to rent these un-exploited resources to distant water fleets (DWFs) from other nations through access agreements. We present an analysis of access agreements signed between DWFs and the Republic of Madagascar valid in 2011. All agreements were appraised based on a number of criteria, including reporting requirements, fees, observers, restrictions and bycatch limits. Our findings highlight consistent severe shortcomings, in particular with regards to the contractual obligations and accountability of DWFs in reporting catches which result in signatories having no disincentive for over-exploitation and illegal fishing. Our analysis shows that of a total of seven agreements authorizing fishing by 170 vessels, only one agreement has a quota in place. Only two require mandatory inspection before a fishing campaign. One agreement is exempt from having any observers on boats and the European Union, whose fleet accounts the majority of licensed vessels (124), does not address the issue of bycatch. Our findings highlight many of the challenges faced by coastal developing nations in renting their fisheries resources. Whilst it is widely recognized that such states need assistance in improving MCS capacity, our analysis suggests that technical assistance in contract development and negotiation should be a fundamental pre-requisite to establishing a fair and sustainable fisheries access agreement framework

Subcellular localization of microcystin in the liver and the gonads of medaka fish acutely exposed to microcystin-LR

International audienceAmong the diverse toxic components produced by cyanobacteria, microcystins (MCs) are one of the most toxic and notorious cyanotoxin groups. Besides their potent hepatotoxicity, MCs have been revealed to induce potential reproductive toxicity in various animal studies. However, little is still known regarding the distribution of MCs in the reproductive organ, which could directly affect reproductive cells. In order to respond to this question, an acute study was conducted in adult medaka fish (model animal) gavaged with 10 μg.g −1 body weight of pure MC-LR. The histological and immunohistochemical examinations reveal an intense distribution of MC-LR within hepatocytes along with a severe liver lesion in the toxin-treated female and male fish. Besides being accumulated in the hepatocytes, MC-LR was also found in the connective tissue of the ovary and the testis, as well as in oocytes and degenerative spermatocyte-like structures but not spermatocytes. Both liver and gonad play important roles in the reproductive process of oviparous vertebrates. This observation constitutes the first observation of the presence of MC-LR in reproductive cells (female, oocytes) of a vertebrate model with in vivo study. Our results, which provide intracellular localization of MC-LR in the gonad, advance our understanding of the potential reproductive toxicity of MC-LR in fish