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An FEL test facility is built on the existing MAX-lab linac system in collaboration between MAX-lab and BESSY. The goal is to study and analyse seeding, harmonic generation, beam compression and diagnostic techniques with the focus of gaining knowledge and experience for the MAX IV FEL and the BESSY FEL projects. The test facility will in the first stage be using the 400 MeV linac beam to generate
An undulator operating at radiation wavelengths between 250 and 2000 Å has been constructed at the Technical Research Centre of Finland and recently installed at the MAX storage ring in Lund. The undulator utilizes ferrite permanent magnets in the hybrid configuration. The magnetic and mechanical design, calculated performance and influence on the electron beam of the undulator are discussed.
Though the pandemic has passed, social media-based messaging continues to exhibit COVID-19-related cues (e.g., wearing a face mask to stay safe), continuing to foster consumers’ health-protective behavior. However, it remains unclear how social media communications (e.g., advertising) affect such behavior, exposing an important literature-based gap. Addressing this gap, we deploy Ducoffe’s adverti
A growing number of primary school students experience difficulties with grapho-motor skills involved in handwriting, which impact both form and content of their texts. Therefore, it is important to assess and monitor handwriting skills in primary school via standardized tests and detect specific grapho-motor parameters (GMPs) which impact handwriting legibility. Multiple standardized tools are av
This paper describes the shape optimization of hyperelastic structures exhibiting finite deformation and contact. The structure's shapes are parameterized with B-splines and the spline control point coordinates serve as the design variables. This design parametrization provides precise boundary representations and analytical sensitivity computations. To accommodate non-matching grids between the c
We show that the Hausdorff dimension of the closure of the second Grigorchuk group is 43/128. Furthermore, we establish that the second Grigorchuk group is super strongly fractal and that its automorphism group equals its normalizer in the full automorphism group of the tree.
The class of multi-EGS groups is a generalisation of the well-known Grigorchuk–Gupta–Sidki (GGS-)groups. Here we classify branch multi-EGS groups with the congruence subgroup property and determine the profinite completion of all branch multi-EGS groups. Additionally, our results show that branch multi-EGS groups are just infinite.
Let w be a word in k variables. For a finite nilpotent group G, a conjecture of Amit states that Nw(1) ≥ | G| k-1, where for g∈ G, the quantity Nw(g) is the number of k-tuples (g1, … , gk) ∈ G(k) such that w(g1, … , gk) = g. Currently, this conjecture is known to be true for groups of nilpotency class 2. Here we consider a generalized version of Amit’s conjecture, which states that Nw(g) ≥ | G| k-
For a generalized (or non-central) camera model, the minimal problem for two views of six points has efficient solvers. However, minimal problems of three views with four points and three views of six lines have not yet been explored and solved, despite the efforts from the computer vision community. This paper develops the formulations of these two minimal problems and shows how state-of-the-art
Research connecting text and images has recently seen several breakthroughs, with models like CLIP, DALL•E 2, and Stable Diffusion. However, the connection between text and other visual modalities, such as lidar data, has received less attention, prohibited by the lack of text-lidar datasets. In this work, we propose LidarCLIP, a mapping from automotive point clouds to a pre-existing CLIP embeddin
The following problem was originally posed by B. H. Neumann and H. Neumann.Suppose that a group 𝐺 can be generated by 𝑛 elements and that 𝐻 is a homomor-phic image of 𝐺. Does there exist, for every generating 𝑛-tuple (ℎ1, … , ℎ 𝑛) of 𝐻,a homomorphism 𝜗 ∶ 𝐺 → 𝐻 and a generating 𝑛-tuple (𝑔1, … , 𝑔 𝑛) of 𝐺 such that(𝑔 𝜗1 , … , 𝑔 𝜗𝑛) = (ℎ1, … , ℎ 𝑛)?M. J. Dunwoody gave a negative
Using wreath products, we construct a finitely generated pro-p group G with infinite normal Hausdorff spectrum here hdim p G : (X|X ⊂ G) [0,1]denotes the Hausdorff dimension function associated to the p-power series p:Gpi, i ε N0 More precisely, we show that hspec p (G)=[0,1/3] ∪ (1) contains an infinite interval; this settles a question of Shalev. Furthermore, we prove that the normal Hausdorff s
Let G be a finitely generated pro-p group, equipped with the p-power series P:Gi=GPi, i ∈ ℕ0. The associated metric and Hausdorff dimension function hdimGP:{X|X⊆G}→[0,1] give rise to hspecP(G)={hdimGP(H)|H≤G}⊆[0,1], the Hausdorff spectrum of closed subgroups of G. In the case where G is p-adic analytic, the Hausdorff dimension function is well understood; in particular, hspecP(G) consists of finit
A multi-edge spinal group is a subgroup of the automorphism group of a regular p-adic rooted tree, generated by one rooted automorphism and a finite number of directed automorphisms sharing a common directing path. We prove that torsion multi-edge spinal groups do not have maximal subgroups of infinite index. This generalizes a result of Pervova for GGS-groups.
Let G be a finite group. We show that the order of the subgroup generated by coprime γk-commutators (respectively,δk- commutators) is bounded in terms of the size of the set of coprime γk-commutators (respectively, δk-commutators). This is in parallel with the classical theorem due to Turner-Smith that the words γk and δk are concise.
A group G is n-central if Gn ≤ Z(G), that is the subgroup of G generated by n-powers of G lies in the centre of G. We investigate p k -central groups for p a prime number. For G a finite group of exponent pk , the covering group of G is pk -central. Using this we show that the exponent of the Schur multiplier of G is bounded by p⌈c/p-1⌉, where c is the nilpotency class of G. Next we give an explic
In a previous paper, Button and Thillaisundaram proved that all finitely presented groups of p-deficiency greater than one are p-large. Here we prove that groups with a finite presentation of p-deficiency one possess a finite index subgroup that surjects onto the integers. This implies that these groups do not have Kazhdan's property (T). Additionally, we show that the aforementioned result of But
A p-group G is p-central if Gp ≤ Z(G), and G is p2-abelian if (xy)p2 = xp2 yp2 for all x; y ε G. We prove that for G a finite p2-abelian p-central p-group, excluding certain cases, the order of G divides the order of Aut(G).
