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Digital Ethics Canvas: a Guide for Ethical Risk Assessment and Mitigation in the Digital Domain
Get PDFPluralité de résiliations et protection dans les cas clairs en matière d’évacuation
Get PDFRésumé et analyse, Tribunal fédéral - 4A_12/2023, Ire Cour de droit civil, Arrêt du 31 mars 202
Quantum cascade lasers for frequency comb-based mid-infrared applications
Get PDFPhD jury:
Prof. Thomas Südmeyer, Director
Dr. Valentin Wittwer, Examiner
Prof. Jérôme Faist, Examiner
Prof. Anne Amy-Klein, Examiner
Prof. Piotr Masłowski, Examiner
No de thèse : 3062La région de l’infrarouge moyen (IRM) du spectre électromagnétique est carac-
térisée par de fortes interactions moléculaires avec la lumière et de faibles pertes
par diffusion. Il s’agit donc d’une gamme de longueurs d’onde stratégique pour
la détection, les télécommunications en espace libre et la spectroscopie de haute
précision. Les peignes de fréquence optiques (PFO ou PF) excellent dans ces
applications, ce qui rend leur génération dans l’IRM très pertinente. Les lasers
à cascade quantique (LCQ) sont une source possible de PFO dans l’IRM et
présentent les avantages uniques d’une puissance d’émission élevée, d’un fonc-
tionnement simple et d’une compatibilité avec la production de masse. Cepen-
dant, malgré leur potentiel, les PF LCQ n’ont pas encore été utilisés dans une
large gamme d’applications dans l’IRM. En fait, il y a un manque de méthodes
établies pour leur contrôle cohérent, comme la stabilisation de la fréquence :
les techniques d’autres technologies de PFO n’ont pas pu être adaptées de ma-
nière directe. Jusqu’à présent, les PF LCQ ont été utilisés presque exclusivement
pour la spectroscopie à double peigne (SDP), où la stabilisation active n’était
pas impérative. En l’absence d’autres sources de PFO simples dans cette gamme
spectrale, elles ont donné d’excellents résultats dans cette configuration. Mais
pour que les PF LCQ puissent accéder aux nombreuses applications de peigne,
il faudra des techniques de stabilisation avancées qui, dans l’idéal, ne nuisent
pas à la simplicité et à la compacité des LCQ.
Dans cette thèse, j’ai étudié la stabilisation de la fréquence, l’étalonnage et
l’application des LCQ dans le but de démontrer leur aptitude en tant que sources
polyvalentes de PF dans l’IRM. Dans une première approche, j’ai abordé le
problème du faible rapport cyclique causé par la correction computationnelle
nécessaire à la SDP en fonctionnement libre. J’ai développé un schéma pour
verrouiller mutuellement deux PF LCQ et pour permettre le traitement en temps
réel du battement multihétérodyne. Un défi pour les schémas de stabilisation
des peignes LCQ est la réponse en fréquence modérée de la méthode de contrôle
habituelle basée sur la rétroaction électrique. Dans une deuxième approche, j’ai
caractérisé l’influence de la lumière de l’infrarouge proche sur un PF LCQ et j’ai
développé un schéma d’asservissement utilisant un laser de télécommunication
standard, améliorant la capacité de verrouillage fin à un niveau satisfaisant pour
la plupart des applications. En outre, j’ai démontré une grande pureté spectrale
sur toute la largeur de bande du peigne et révélé la cohérence du peigne à
de nouvelles échelles de temps. Dans une troisième expérience, j’ai réalisé la
stabilisation complète de la fréquence d’un PF LCQ dans l’IRM. J’ai ensuite
mis en œuvre une spectroscopie calibrée par peigne et récupéré la fréquence
centrale de plusieurs transitions moléculaires. L’accord précis entre les valeurs
extraites et celles de la littérature prouve que les PF LCQ conviennent aux
applications de métrologie des fréquences. Dans une dernière expérience, j’ai
abordé la question de l’étalonnage de la fréquence dans le cadre de la SDP rapide
et à haute résolution. J’ai conçu et testé un schéma qui a permis la combinaison
critique de précision de fréquence, de vitesse d’acquisition, de résolution et de
sensibilité élevées. Il s’est avéré que le taux de répétition particulièrement élevé
des LCQ est en fait un avantage pour la spectroscopie à peigne direct.
Tous ces résultats peuvent déjà être transférés vers des applications. Par
exemple, la capacité de verrouillage fin permettra d’utiliser des cavités d’amé-
lioration pour augmenter la sensibilité. En outre, l’étalonnage de la fréquence
en SDP rapide et à haute résolution permet d’utiliser les LCQ pour des études
de haute précision sur la physique des molécules. Cependant, les résultats rap-
portés ne représentent que la partie émergée de l’iceberg en ce qui concerne
le potentiel des PF LCQ pour exploiter les possibilités de l’IRM. Bien qu’ils
ne fassent qu’effleurer la surface, ils établissent concrètement que les LCQ sont
adaptés en termes de stabilisation de fréquence et d’étalonnage en tant que
sources de PF polyvalentes dans l’IRM. Des développements supplémentaires en
matière d’intégration photonique, d’émission d’impulsions et de faible consom-
mation d’énergie promettent de rendre les LCQ incontournables dans la société
de l’avenir.
Abstract
The mid-infrared (MIR) part of the electromagnetic spectrum is characterized
by strong molecular interactions with light and low scattering losses. Thus, it
is a strategic wavelength range for sensing, free-space telecommunications and
high-precision spectroscopy. Optical frequency combs (OFCs or FCs) excel in
these applications, making their generation in the MIR highly relevant. Quan-
tum cascade lasers (QCLs) are a possible source of MIR OFCs, and present
the unique merits of high emission power, simple operation, and compatibility
with mass-production. However, QCL OFCs have not yet been employed in
a wide range of MIR applications despite their potential. In fact, there is a
lack of established methods for their coherent control such as frequency sta-
bilization: techniques from other OFC technologies could not be adapted in
a straightforward manner. So far, they have been used almost exclusively for
dual comb spectroscopy (DCS), where active stabilization was not imperative.
In the absence of other simple OFC sources in this spectral range, they have
been producing excellent results in this configuration. But enabling QCL FCs
to drive the manifold of comb applications will require advanced stabilization
techniques that ideally do not undermine simplicity and compactness.
In this thesis, I investigated frequency stabilization, calibration, and the ap-
plication of QCLs with the goal of demonstrating their fitness as versatile MIR
FC sources. In a first approach, I tackled the issue of low duty-cycle impaired
by the computational correction necessary for free running DCS. I developed
a scheme to mutually lock two QCL FCs and to allow real-time processing of
the multiheterodyne beat. One challenge for QCL comb stabilization schemes is
the moderate frequency response of the usual control method based on electrical
feedback. In a second approach, I characterized the influence of near-infrared
light on a QCL FC and developed a locking scheme employing a standard
telecommunication laser, improving the tight-locking ability to a satisfactory
level for most applications. Moreover, I demonstrate high spectral purity across
the bandwidth of the comb and reveal the comb coherence at new time-scales.
In a third experiment, I performed the full frequency stabilization of a MIR QCL
FC. I then implemented comb-calibrated spectroscopy and retrieved the center
frequency of several molecular transitions. The accurate agreement between the
retrieved and literature values proves that QCL FCs are suited for frequency
metrology applications. In a final experiment, I tackled the issue of frequency
calibration in fast and high-resolution DCS. I designed and tested a scheme that
allowed the critical combination of high frequency accuracy, acquisition speed,
resolution, and sensitivity. It was found that the particularly high repetition
rate of QCLs is actually an advantage for direct comb spectroscopy.
All these results can already be transferred to applications. For example, the
tight-locking capability will allow the use of enhancement cavities for increased
sensitivity. Moreover, frequency calibration in fast and high resolution DCS al-
lows QCLs to be employed for high precision studies of the physics of molecules.
However, the reported results represent only the tip of the iceberg in the po-
tential of QCL OFCs to harness the prospects of the MIR. While they merely
scratches the surface, they establish concretely that QCLs are fit in terms of
frequency stabilization and calibration as versatile MIR FC sources. Further
development towards photonic integration, pulse emission, and low power con-
sumption promise to make QCLs ubiquitous in the society of the future
Experimental Growth Conditions affect Direct and Indirect Defences in two Cotton Species
Get PDFCotton has been used as a model plant to study direct and indirect plant defence against herbivorous insects. However, the plant growing conditions could have an important effect on the outcome of such plant defence studies. We examined how common experimental growth conditions influence constitutive and inducible defences in two species of cotton, Gossypium hirsutum and G. herbaceum. We induced plants by applying caterpillar regurgitant to mechanical wounds to compare the induction levels between plants of both species grown in greenhouse or phytotron conditions. For this we measured defence metabolites (gossypol and heliocides) and performance of Spodoptera frugiperda caterpillars on different leaves, the emission of plant volatiles, and their attractiveness to parasitic wasps. Induction increased the levels of defence metabolites, which in turn decreased the performance of S. frugiperda larvae. Constitutive and induced defence levels were the highest in plants grown in the phytotron (compared to greenhouse plants), G. hirsutum and young leaves. Defence induction was more pronounced in plants grown in the phytotron and in young leaves. Also, the differences between growing conditions were more evident for metabolites in the youngest leaves, indicating an interaction with plant ontogeny. The composition of emitted volatiles was different between plants from the two growth conditions, with greenhouse-grown plants showing more variation than phytotron-grown plants. Also, G. hirsutum released higher amounts of volatiles and attracted more parasitic wasps than G. herbaceum. Overall, these results highlight the importance of experimental abiotic factors in plant defence induction and ontogeny of defences. We therefore suggest careful consideration in selecting the appropriate experimental growing conditions for studies on plant defences
Switzerland and Germany: Regulation of the digital economy - Blessing or curse?
Get PDFGlobally, the demand for digital services is concentrated among a small number of extremely powerful companies. The ongoing international debate on competition policy explores whether ex post abuse control under competition law should be complemented by ex ante regulation.
Drawing insights from Lukas Valis’ PhD thesis, supervised by Blaise Carron, which discussed these issues by investigating the existing regulation of the [Tele]Communications sector in Germany and Switzerland, the authors examine recent developments in Germany and propose a balanced solution to mitigate potential negative effects of an ex ante regulation of the digital economy.tru
Demo-economic analysis of player transfers (2014-2023)
No full textThis report analyses the financial flows of football transfers on a global scale during the decade between 2014 and 2023. It presents the evolution of transfer fees incurred by clubs, their breakdown according to the age and position of the players concerned or the geographical area of recruiting teams, as well as the economic balance sheets of transfer operations, at both league and club level
La décision intermédiaire en procédure de mesures protectrices
Get PDFRésume et analyse, Tribunal fédéral – 5A_325/2022, 5A_327/2022, IIème Cour de droit civil, Arrêt du 8 juin 202
Virulence Associations and Global Context of Genetic Diversity in Iranian Populations of Zymoseptoria tritici
No full textManaging pathogen damage in wheat production is important for sustaining yields. Fungal plant pathogen genomes encode many small secreted proteins acting as effectors that play key roles in the successful colonization of host tissue and triggering host defenses. is the first described avirulence effector, which triggers -mediated immunity in the wheat host in a gene-for-gene manner. Evasion of major resistance factors such as challenges deployment decisions on wheat cultivars. In this study, we analyzed the evolution of the effector in Iranian isolates of . In total, 78 isolates were isolated and purified from 30 infected wheat specimens collected from the East Azerbaijan and Ardabil provinces of Iran. The pathogenicity of all isolates was evaluated on the susceptible wheat cultivar 'Tajan'. A subset of 40 isolates were also tested for pathogenicity on the resistant cultivar 'Shafir' carrying . Genetic diversity at the locus was analyzed for 14 isolates covering the breadth of the observed disease severity. The sequence variation was high, with virulent isolates carrying highly diverse haplotypes. In an analysis including more than 1,000 additional sequences from a global set of isolates, we found that virulent isolates carried haplotypes either clustering with known virulent haplotypes on different continents or constituting previously unknown haplotypes. Furthermore, we found that variants from avirulent isolates clustered with known avirulent genotypes from Europe. Our study highlights the relevance of for virulence and the exceptional global diversity patterns of this effector
Pre-Print!! Migranticization
No full textMigranticization can be understood as those sets of performative practices that ascribe a migratory status to certain people and bodies – labelling them (im)migrants, second-generation migrants, people with migration background, minorities, etc. – and thus (re-)establish their a priori non-belonging, regardless of whether the people designated as ‘migrants’ are citizens of the nation-state they reside in or not, and regardless of whether they have crossed a national border or not. Migranticization can be considered as a technology of power and governance; it places people in a distinct hierarchy which goes along with an unequal distribution of societal symbolic and material resources while it affirms a national ‘we’ within a system of global inequalities. The suggestion is to use migranticization as an analytical lens which makes it possible to investigate the uses of migration-related categories and their consequences in terms of power and ex/inclusion from/in a global system of inequalities and nation-states
PPE 2023
No full textPublié à l'occasion de la 5e Journée de la PPE, organisée le 22 septembre 2023 par le Centre bail et PPE de l'Université de Neuchâtel, en collaboration avce la chambre immobilière vaudois