The Weyl-Heisenberg Group on the Noncommutative Two-Torus: A Zoo of Representations

In order to assess possible observable effects of noncommutativity in deformations of quantum mechanics, all irreducible representations of the noncommutative Heisenberg algebra and Weyl-Heisenberg group on the two-torus are constructed. This analysis extends the well known situation for the noncommutative torus based on the algebra of the noncommuting position operators only. When considering the dynamics of a free particle for any of the identified representations, no observable effect of noncommutativity is implied.Comment: 24 pages, no figure

Constraints on the impact of active galactic nuclei on star formation in galaxies

Super massive black holes (SMBH) are known to reside at the centre of massive galaxies, and are visible during their growth phases as active galactic nuclei (AGN). Current theoretical models of galaxy evolution require AGN feedback processes to reproduce many of the fundamental properties of galaxies and the intergalactic medium. In an effort to constrain the effect of AGN feedback on star formation in AGN host galaxies, this thesis uses observations to test predictions from the cosmological simulations. I present ALMA and integral field unit (IFU) observations of AGN host galaxies to trace obscured and unobscured star formation as well as ionised gas kinematics. Using deep ALMA continuum observations and multi-wavelength photometry I estimate specific star formation rate distributions of 81 X-ray AGN at z=1.5--3.2 with AGN luminosities of $10^{43}$--$10^{45}$ ergs s$^{-1}$. Comparison of the observations with predictions from the EAGLE cosmological simulations shows that AGN feedback is responsible for broadening the sSFR distribution of both active and inactive galaxies by suppressing their star formation. In the second scientific experiment, I present IFU and ALMA observations of eight X-ray AGN at z=1.4--2.6 with AGN luminosities of $10^{42}$--$10^{45}$ ergs s$^{-1}$ to investigate the connection between AGN driven ionised outflows and star formation. Using these observations, I conclude that star formation in AGN host galaxies is not instantly suppressed by AGN driven outflows, consistent with the global conclusions from my earlier study. I reach this conclusion whenever I use obscured or unobscured star formation tracer. Furthermore, I conclude that it is necessary to use H$\alpha$ emission with caution when using it to trace star formation in AGN host galaxies. In the last scientific experiment, I investigate star formation in three quasars at z$\sim$2.5 that were previously presented in the literature as having evidence for suppressed star-formation at the location of ionised outflows. Using new ALMA band 7 continuum observations and re-analysing the existing archival H$\alpha$ observations, I do not observe any suppression of star formation in these quasars. Based on the evidence from all of my studies, I conclude that AGN feedback does not instantly suppress star formation on a global scale, but rather the feedback may have an impact seen on smaller spatial scales ($<$ 4 kpc), or on longer timescales than a single AGN episode

Variations on the Planar Landau Problem: Canonical Transformations, A Purely Linear Potential and the Half-Plane

The ordinary Landau problem of a charged particle in a plane subjected to a perpendicular homogeneous and static magnetic field is reconsidered from different points of view. The role of phase space canonical transformations and their relation to a choice of gauge in the solution of the problem is addressed. The Landau problem is then extended to different contexts, in particular the singular situation of a purely linear potential term being added as an interaction, for which a complete purely algebraic solution is presented. This solution is then exploited to solve this same singular Landau problem in the half-plane, with as motivation the potential relevance of such a geometry for quantum Hall measurements in the presence of an electric field or a gravitational quantum well

Impact of ownership structure along the value chain in the manufacturing business

In the chemical and petrochemical industry, it is quite common that the manufacturing of a final product is the result of several consecutive steps which can be owned and operated by one or many participants. Although not always practical, equal ownership among all partners along the value chain is often recommended as a way to simplify business structure, ensuring all partners share equally in the ups and downs of an uncertain market. In contrast to this approach, there are instances where more benefit can be derived from having different owners and operators along the value chain. Examples which are common practice in the industry are the supply of utilities (e.g., electricity), feedstock, and services. In these cases, the nonintegrated approach offers value as: It provides the operator of the upstream or utility plants the opportunity to specialize, for example, by operating very similar plants around the world. Such specialization enables the use of regional operating centers, minimum onsite cash costs, optimized operating conditions, minimized energy consumption, and the optimal use of other variable cost parameters. This article shows that if outsourcing results in a cash cost saving by an upstream operator, the benefit to the downstream owner will (in financial reward) be proportional to the cash cost saving achieved. In absolute terms, the magnitude of the benefit is moderated by the size of the downstream capital investment (The bigger the downstream investment relative to the upstream investment, the smaller the impact of the saving on the economics of the downstream company). As a “utility provider” an upstream operator benefits from lower risk in terms of offtake and market price uncertainties. Such owners benefit from a lower cost of capital, and as such also have lower return expectations than players further along in the value chain (who are exposed to all the uncertainties in volatile markets). This article shows that the positive impact of such benefits to the return of the downstream partner is directly proportional the difference in return expectations between the upstream and downstream company. Once again, the absolute magnitude of the saving becomes more substantial as the ratio of upstream capital investment increases relative to the downstream capital investment. Economy of learning may also enable a specialized upstream company to obtain an asset at a lower capital than a less specialized downstream operator. This article shows that the positive impact of such a benefit is very similar to that of a lower return expectation by the upstream company.http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1547-59052017-04-30hb2016Chemical Engineerin

The N=1 Supersymmetric Landau Problem and its Supersymmetric Landau Level Projections: the N=1 Supersymmetric Moyal-Voros Superplane

The N=1 supersymmetric invariant Landau problem is constructed and solved. By considering Landau level projections remaining non trivial under N=1 supersymmetry transformations, the algebraic structures of the N=1 supersymmetric covariant non(anti)commutative superplane analogue of the ordinary N=0 noncommutative Moyal-Voros plane are identified

Silver nanoparticles with plasma-polymerized hexamethyldisiloxane coating on 3D printed substrates are non-cytotoxic and effective against respiratory pathogens

Due to the emerging resistance of microorganisms and viruses to conventional treatments, the importance of self-disinfecting materials is highly increasing. Such materials could be silver or its nanoparticles (AgNPs), both of which have been studied for their antimicrobial effect. In this study, we compared the biological effects of AgNP coatings with and without a plasma-polymerized hexamethyldisiloxane (ppHMDSO) protective film to smooth silver or copper coatings under three ambient conditions that mimic their potential medical use (dry or wet environments and an environment simulating the human body). The coatings were deposited on 3D printed polylactic acid substrates by DC magnetron sputtering, and their surface morphology was visualized using scanning electron microscopy. Cytotoxicity of the samples was evaluated using human lung epithelial cells A549. Furthermore, antibacterial activity was determined against the Gram-negative pathogenic bacterium Pseudomonas aeruginosa PAO1 and antiviral activity was assessed using human rhinovirus species A/type 2. The obtained results showed that overcoating of AgNPs with ppHMDSO creates the material with antibacterial and antiviral activity and at the same time without a cytotoxic effect for the surrounding tissue cells. These findings suggest that the production of 3D printed substrates coated with a layer of AgNPs-ppHMDSO could have potential applications in the medical field as functional materials

Charge-charge interactions are key determinants of the pK values of ionizable groups in ribonuclease Sa (pI=3.5) and a basic variant (pI=10.2)

The pK values of the titratable groups in ribonuclease Sa (RNase Sa) (pI=3.5), and a charge-reversed variant with five carboxyl to lysine substitutions, 5K RNase Sa (pI=10.2), have been determined by NMR at 20 °C in 0.1 M NaCl. In RNase Sa, 18 pK values and in 5K, 11 pK values were measured. The carboxyl group of Asp33, which is buried and forms three intramolecular hydrogen bonds in RNase Sa, has the lowest pK (2.4), whereas Asp79, which is also buried but does not form hydrogen bonds, has the most elevated pK (7.4). These results highlight the importance of desolvation and charge–dipole interactions in perturbing pK values of buried groups. Alkaline titration revealed that the terminal amine of RNase Sa and all eight tyrosine residues have significantly increased pK values relative to model compounds. A primary objective in this study was to investigate the influence of charge–charge interactions on the pK values by comparing results from RNase Sa with those from the 5K variant. The solution structures of the two proteins are very similar as revealed by NMR and other spectroscopic data, with only small changes at the N terminus and in the α-helix. Consequently, the ionizable groups will have similar environments in the two variants and desolvation and charge–dipole interactions will have comparable effects on the pK values of both. Their pK differences, therefore, are expected to be chiefly due to the different charge–charge interactions. As anticipated from its higher net charge, all measured pK values in 5K RNase are lowered relative to wild-type RNase Sa, with the largest decrease being 2.2 pH units for Glu14. The pK differences (pKSa−pK5K) calculated using a simple model based on Coulomb's Law and a dielectric constant of 45 agree well with the experimental values. This demonstrates that the pK differences between wild-type and 5K RNase Sa are mainly due to changes in the electrostatic interactions between the ionizable groups. pK values calculated using Coulomb's Law also showed a good correlation (R=0.83) with experimental values. The more complex model based on a finite-difference solution to the Poisson–Boltzmann equation, which considers desolvation and charge–dipole interactions in addition to charge–charge interactions, was also used to calculate pK values. Surprisingly, these values are more poorly correlated (R=0.65) with the values from experiment. Taken together, the results are evidence that charge–charge interactions are the chief perturbant of the pK values of ionizable groups on the protein surface, which is where the majority of the ionizable groups are positioned in proteins.This work was supported by grants GM-37039 and GM-52483 from the National Institutes of Health (USA), grants BE-1060 and BE-1281 from the Robert A. Welch Foundation, and a grant PB-93-06777 to M.R. from the Dirección General de Investigación Cientı́fica y Técnica (Spain

Bubbles and outflows: the novel JWST/NIRSpec view of the z=1.59 obscured quasar XID2028

Quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation in galaxies, although direct observational evidence is still scarce and debated. Here we present Early Release Science JWST NIRSpec IFU observations of the z=1.59 prototypical obscured quasar XID2028: this target represents a unique test case to study QSO feedback at the peak epoch of AGN-galaxy co-evolution thanks to its existing extensive multi-wavelength coverage and massive and extended outflow detected both in the ionised and molecular components. With the unprecedented sensitivity and spatial resolution of JWST, the NIRSpec dataset reveals a wealth of structures in the ionised gas kinematics and morphology previously hidden in the seeing-limited ground-based data. In particular, we find evidence of interaction between the interstellar medium of the galaxy and the QSO-driven outflow and radio jet, which is producing an expanding bubble from which the fast and extended wind detected in previous observations is emerging. The new observations confirm the complex interplay between the AGN jet/wind and the ISM of the host galaxy, highlighting the role of low luminosity radio jets in AGN feedback, and showcase the new window opened by NIRSpec on the detailed study of feedback at high redshift.Comment: 12 pages, 11 figures, submitted to A&A. Comments welcom

Spatially resolved emission lines in galaxies at 4≤z<104\leq z < 10 from the JADES survey: evidence for enhanced central star formation

We present the first statistical investigation of spatially resolved emission-line properties in a sample of 63 low-mass galaxies at $4\leq z<10$, using JWST/NIRSpec MSA data from the JWST Advanced Deep Extragalactic (JADES) survey focusing on deep, spatially resolved spectroscopy in the GOODS-S extragalactic field. By performing a stacking of the 2D spectra of the galaxies in our sample, we find an increasing or flat radial trend with increasing radius for [OIII]$\lambda5007$/H$\beta$ and a decreasing one for [NeIII]$\lambda3869$/[OII]$\lambda3727$ (3--4 $\sigma$ significance). These results are still valid when stacking the sample in two redshift bins (i.e., $4\leq z<5.5$ and $5.5\leq z<10$). The comparison with star-formation photoionization models suggests that the ionization parameter increases by $\sim 0.5$ dex with redshift. We find a tentative metallicity gradient that increases with radius (i.e., 'inverted') in both redshift bins. Moreover, our analysis reveals strong negative gradients for the equivalent width of \Hbeta (7$\sigma$ significance). This trend persists even after removing known AGN candidates, therefore, it is consistent with a radial gradient primarily in stellar age and secondarily in metallicity. Taken all together, our results suggest that the sample is dominated by active central star formation, with possibly inverted metallicity gradients sustained by recent episodes of accretion of pristine gas or strong radial flows. Deeper observations and larger samples are needed to confirm these preliminary results and to validate our interpretation.Comment: 15 pages, 13 Figures, 1 Table. Submitted to A&