Passive Covert Radars using CP-OFDM SFN. Reference signal recovery from blind beamforming

A passive Coherent Location (PCL) system uses the signal transmitted by so called illuminators-of-opportunity in the environment for the illumination of targets. It is then necessary to recover the original transmitted signal to be compared to the targets echoes. With CP-OFDM transmissions, it is quite easy to recover the original data and then to reconstruct the original transmission. But in the case of a Single Frequency Network , characterized by the presence of several transmitters using the same carrier frequency to broadcast the same signal, it is necessary to use directional sensors or spatial filter. In this paper, we propose two blind solutions : classical beamforming and CAPON filtering. Results of real measurements are presented

Addressing gender-based segregation through information : evidence from a randomized experiment in the republic of Congo

This paper describes a randomized experiment that used a sample of men and women who were eligible for a vocational training program in the Republic of Congo to test the effect of providing information on trade-specific earnings on trade choice. The analysis finds that women are 28.6 percent more likely to apply to a traditionally male- dominated trade when receiving this information. Men and women are also both more likely to apply to more lucrative trades. This may in part be driven by the intervention filling an information gap. The analysis suggests, however, that behavioral mechanisms, which make trade-specific returns more salient in the decision process of applicants, play an even bigger role. Indeed, there are much larger treatment effects among women who have technical knowledge and experience or male role models, even though the information does not impact their expectations of earnings in male-dominated trades. The treatment is thus most effective among women who are already well positioned to cross over into male-dominated trades and can give greater weight to earning considerations when choosing a trade. The results indicate that this low-cost intervention can be a useful tool to encourage women to cross over to more lucrative trades in which their presence has been limited, and thereby contribute to reducing the gender gap in earnings. There is also a high potential for interventions that would pair information on returns and trade exposure

Interplay of coprecipitation and adsorption processes: Deciphering amorphous mineral–organic associations under both forest and cropland conditions

Mineral–organic associations are crucial carbon and nutrient reservoirs in soils. However, conversion from forest to agricultural systems disrupts these associations, leading to carbon loss and reduced soil fertility in croplands. Identifying the types of mineral–organic associations within a single soil is already challenging, and detecting those susceptible to disruption during forest-to-crop conversion is even more complex. Yet, addressing this identification challenge is essential for devising strategies to preserve organic matter in croplands. Here, we aimed to identify the predominant mineral–organic associations within an Andosol (developed on Fe-poor parent material) under both forest and cropland conditions. To achieve this, we collected Andosol samples from both a forested and a cultivated area, located 300 m apart. We then analyzed differences between the two soil profiles in soil physicochemical parameters and characterized mineral–organic associations using an array of spectro-microscopic techniques for comprehensive structural and compositional analysis. At microscale and nanoscale spatial resolution, we observed mineral–organic associations in the form of amorphous coprecipitates, composed of a mix of C+Al+Si and C+Al+Fe+Si nanoCLICs (inorganic oligomers with organics), proto-imogolites and organic matter, some Fe nanophases associated with organic matter, and some metal–organic complexes. This challenges prior conceptions of mineral–organic associations in Andosols by demonstrating the presence of amorphous coprecipitates rather than solely organic matter associated with short-range-order minerals (i.e., imogolite and allophanes). Moreover, chemical mappings suggested that these amorphous coprecipitates may adhere to mineral surfaces (i.e., phyllosilicates and imogolites), revealing secondary interactions of mineral–organic associations in soils. While the presence of similar amorphous coprecipitates in both the forest and crop Andosols was confirmed, the crop soil had 75 % less C in mineral–organic associations (in the 0–30 cm depth). Although the sample size for comparing land use types is limited, these results suggest that the nature of mineral–organic associations remains identical despite quantitative differences. This study highlights the crucial role of amorphous coprecipitates in C stabilization in Andosols and also suggests their vulnerability to disruption after 30 years of a forest-to-crop conversion, thereby challenging our understanding of the persistence of mineral–organic associations in Andosols

Beneficial effects of reduced soft tissue vibrations with compression garments on delayed neuromuscular impairments induced by an exhaustive downhill run

IntroductionSoft tissue vibrations (STV) have been extensively researched for their effects on muscle fatigue and damage, but their influence during running remains unclear. As compression garments are known to lower STV, they have shown benefits on acute neuromuscular responses to downhill running. However, an in-depth analysis of changes in STV has never been proposed, and previous protocols did not overcome the repeated bout effect. This study aims to investigate whether compression shorts could reduce STV parameters and related neuromuscular impairments using a unilateral compression protocol.Materials and methodsTwenty healthy men performed a downhill run until exhaustion while wearing shorts that compressed one thigh with the contralateral leg serving as a control. Foot–ground impacts (FGI), STV, and muscle activation of the Vastus Lateralis were measured on both legs while running using accelerometers to obtain FGI and STV, and surface electromyographic sensors (EMG) for muscle activation. Time–frequency analyses were applied to acceleration and EMG signals with statistical non-parametric mapping applied to the continuous data to assess time and compression effects. Neuromuscular parameters such as maximal voluntary contraction torque, voluntary activation, and torque evoked by 10 and 100 Hz doublet stimulation were assessed before, after, and 48 h post exercise, alongside perceived fatigue and muscle soreness. Mixed linear models and paired Student's t-tests were used to analyze neuromuscular outcomes.ResultsWhile results showed that both FGI and STV magnitude increased during the run by 19.7% (P = 0.002) and 17.8% (P = 0.003), respectively, compression reduced the magnitude and frequency of STV by 15.1% (P = 0.013) and 11.7% (P = 0.001), respectively, without influencing FGI or muscle activation. Although neuromuscular parameters were altered in both legs, losses of torque evoked by 10 and 100 Hz doublets were lower in the compressed leg 48 h post exercise (P < 0.001 and P = 0.001, respectively).ConclusionThis study revealed the potential of compression garments to act as a mechanical support that attenuates high-frequency STV during downhill running and mitigates subsequent delayed neuromuscular alterations

Hydroclimatic vulnerability of peat carbon in the central Congo Basin

The forested swamps of the central Congo Basin store approximately 30 billion metric tonnes of carbon in peat1,2. Little is known about the vulnerability of these carbon stocks. Here we investigate this vulnerability using peat cores from a large interfluvial basin in the Republic of the Congo and palaeoenvironmental methods. We find that peat accumulation began at least at 17,500 calibrated years before present (cal. yr BP; taken as AD 1950). Our data show that the peat that accumulated between around 7,500 to around 2,000 cal. yr BP is much more decomposed compared with older and younger peat. Hydrogen isotopes of plant waxes indicate a drying trend, starting at approximately 5,000 cal. yr BP and culminating at approximately 2,000 cal. yr BP, coeval with a decline in dominant swamp forest taxa. The data imply that the drying climate probably resulted in a regional drop in the water table, which triggered peat decomposition, including the loss of peat carbon accumulated prior to the onset of the drier conditions. After approximately 2,000 cal. yr BP, our data show that the drying trend ceased, hydrologic conditions stabilized and peat accumulation resumed. This reversible accumulation–loss–accumulation pattern is consistent with other peat cores across the region, indicating that the carbon stocks of the central Congo peatlands may lie close to a climatically driven drought threshold. Further research should quantify the combination of peatland threshold behaviour and droughts driven by anthropogenic carbon emissions that may trigger this positive carbon cycle feedback in the Earth system

Passive Covert Radars using CP-OFDM signals. A new efficient method to extract targets echoes

Passive Coherent Location (PCL) systems use the signal transmitted by so called illuminators-of-opportunity in the environment to illuminates the targets. With CP-OFDM transmissions, it is quite easy to recover the original data and then to reconstruct the original transmission. The main difficulty is to extract, from the mixture received on the sensors, only the targets echoes. A new efficient and low complexity method is exposed here. Results on both simulated and real data are presented

« Études des conditions d’appropriation d’un ‘‘dialogue social territorial’’, vers une gouvernementalisation des pratiques syndicales ? »

International audienc

« La dépolitisation par le dialogue social territorial »

International audienc

Armed groups' modes of local engagement and post-conflict (in)stability: Insights from the Ethiopian and Somali civil wars

What distinguishes post-war governments that succeed in establishing a stable political order and prevent recurring conflict from those that do not? This comparative study considers the specific threats that typically lead to the collapse of the post-conflict political order to offer new hypotheses on the conditions that affect post-war governments' ability to sustainably restore stability. The threats considered include (i) fragmentation of the main actors in the conflict, (ii) inadequate demobilization, and (iii) enduring dependence of the post-war government on local brokers. Post-war regimes are more vulnerable to such risks after wars in which the dominant armed groups have established themselves by co-opting local power structures and drawing on existing socio-political networks, as this process redistributes power from the central to the local level. Empirically, this paper uses a novel dataset documenting the practices through which rebel groups may alter local power structures to highlight the connection between this wartime process of transformation and patterns of conflict recurrence. In addition, it contrasts the transition of the Tigray People's Liberation Front from rebellion to government in Ethiopia in the 1990s with the trajectory of the armed movements in Somalia that also overthrew the incumbent military regime but then failed to establish a viable state