Triply mixed coverings of arbitrary base curves: Quasimodularity, quantum curves and a mysterious topological recursions

Simple Hurwitz numbers enumerate branched morphisms between Riemann surfaces with fixed ramification data. In recent years, several variants of this notion for genus $0$ base curves have appeared in the literature. Among them are so-called monotone Hurwitz numbers, which are related to the HCIZ integral in random matrix theory and strictly monotone Hurwitz numbers which count certain Grothendieck dessins d'enfants. We generalise the notion of Hurwitz numbers to interpolations between simple, monotone and strictly monotone Hurwitz numbers to any genus and any number of arbitrary but fixed ramification profiles. This yields generalisations of several results known for Hurwitz numbers. When the target surface is of genus one, we show that the generating series of these interpolated Hurwitz numbers are quasimodular forms. In the case that all ramification is simple, we refine this result by writing this series as a sum of quasimodular forms corresonding to tropical covers weighted by Gromov-Witten invariants. Moreover, we derive a quantum curve for monotone and Grothendieck dessins d'enfants Hurwitz numbers for arbitrary genera and one arbitrary but fixed ramification profile. Thus, we obtain spectral curves via the semiclassical limit as input data for the CEO topological recursion. Astonishingly, we find that the CEO topological recursion for the genus $1$ spectral curve of the strictly monotone Hurwitz numbers compute the monotone Hurwitz numbers in genus $0$. Thus, we give a new proof that monotone Hurwitz numbers satisfy CEO topological recursion. This points to an unknown relation between those enumerants. Finally, specializing to target surface $\mathbb{P}^1$, we find recursions for monotone and Grothendieck dessins d'enfants double Hurwitz numbers, which enables the computation of the respective Hurwitz numbers for any genera with one arbitrary but fixed ramification profile.Comment: 41 page

Folate, vitamin B12 and vitamin D status in healthy and active home-dwelling people over 70 years

Background: Ageing is characterised by physiological changes that can affect the nutrient availability and requirements. In particular, the status of vitamin D, cobalamin and folate has often been found to be critical in older people living in residential care. However, there is a lack of studies investigating the status of these nutrients in healthy and active home-dwelling elderly people. Methods: The aim of this cross-sectional study was to assess the status of vitamin D based on serum concentrations of 25-hydroxycholecalciferol [25-(OH)D], cobalamin based on serum concentrations of holotranscobalamin (holoTC) and folate based on red blood cell (RBC) folate in unsupplemented, healthy and active German home-dwelling subjects ≥ 70 years of age (n = 134, mean ± SD: 75.8 ± 4.5 years). Dietary intake was assessed by 3-day food recalls. The study was conducted between March and November of 2021 (during the COVID-19 pandemic). Results: The mean 25-(OH)D concentration was high at 85.1 ± 26.0 nmol/L, while the majority of women (92%) and men (94%) had 25-(OH)D concentrations ≥ 50 nmol/L. Less than 10% of men and women had 25-(OH)D concentrations < 50 nmol/L. The mean holoTC concentration was 88.9 ± 33.7 pmol/L (94.8 ± 34.6 pmol/L in women and 73.6 ± 25.6 in men). Only 8% of the women were cobalamin deficient (< 50 pmol/L holoTC) compared to 22% of the men. The mean RBC folate concentration was 831 ± 244 nmol/L, while the prevalence of folate deficiency was 10%. Linear regression analysis showed that only folate equivalent intake was associated with the relevant nutrient status marker. Conclusion: Our findings suggest that healthy, independently living older people with high levels of education, physical activity, and health awareness are not necessarily at higher risk of vitamin D, folate and cobalamin deficiency. Further studies are needed to verify these findings and to identify lifestyle and dietary patterns that can predict adequate nutrient status for healthy ageing. Trial registration: This study is officially recorded in the German Clinical Trials Register (DRKS00021302)

Impact of Partial Power Processing Dual-Active Bridge Converter on Li-ion Battery Storage Systems

Partial Power Processing converters (PPPCs) provide economical and highly efficient solutions to integrate battery energy storages systems (BSSs) into DC grids. Beside these significant advantages, direct connection of the batteries by PPPCs to DC grids imposes challenges on the operation of batteries which need more evaluation. DC grid imperfections such as harmonics and faults may directly propagate into BSS and result in battery capacity fade acceleration and/or battery failure. In this paper, low voltage (LV) grid imperfection impacts are compared for conventional dual-active bridge (DAB) and Partial Power Processing DAB (PPP-DAB) converters. Both theoretical and experimental studies are carried out. The obtained results show that PPP-DAB exposes the BSS to high amount of current harmonics and safety issues

Year-round tracking of small trans-Saharan migrants using light-level geolocators

Since 1899 ringing (or banding) remained the most important source of information about migration routes, stopover sites and wintering grounds for birds that are too small to carry satellite-based tracking systems. Despite the large quantity of migrating birds ringed in their breeding areas in Europe, the number of ring recoveries from sub-Saharan Africa is very low and therefore the whereabouts of most small bird species outside the breeding season remain a mystery. With new miniaturized light-level geolocators it is now possible to look beyond the limits of ring recovery data. Here we show for the first time year round tracks of a near passerine trans-Saharan migrant, the European Hoopoe (Upupa epops epops). Three birds wintered in the Sahel zone of Western Africa where they remained stationary for most of the time. One bird chose a south-easterly route following the Italian peninsula. Birds from the same breeding population used different migration routes and wintering sites, suggesting a low level of migratory connectivity between breeding and wintering areas. Our tracking of a near passerine bird, the European Hoopoe, with light-level geolocators opens a new chapter in the research of Palaearctic-African bird migration as this new tool revolutionizes our ability to discover migration routes, stopover sites and wintering grounds of small birds

Loosely-Stabilizing Phase Clocks and The Adaptive Majority Problem

We present a loosely-stabilizing phase clock for population protocols. In the population model we are given a system of n identical agents which interact in a sequence of randomly chosen pairs. Our phase clock is leaderless and it requires O(log n) states. It runs forever and is, at any point of time, in a synchronous state w.h.p. When started in an arbitrary configuration, it recovers rapidly and enters a synchronous configuration within O(n log n) interactions w.h.p. Once the clock is synchronized, it stays in a synchronous configuration for at least poly(n) parallel time w.h.p. We use our clock to design a loosely-stabilizing protocol that solves the adaptive variant of the majority problem. We assume that the agents have either opinion A or B or they are undecided and agents can change their opinion at a rate of 1/n. The goal is to keep track which of the two opinions is (momentarily) the majority. We show that if the majority has a support of at least ?(log n) agents and a sufficiently large bias is present, then the protocol converges to a correct output within O(n log n) interactions and stays in a correct configuration for poly(n) interactions, w.h.p

Multiwinding Transformer Leakage Inductance Optimization for Power Flow Decoupling in Multiport DC-DC Converters

Isolated multiport DC-DC converters manifest some prominent advantages over usual multiple two-port DC-DC converters such as smaller holistic magnetics and higher power density. However, the operation of such a converter is tied to the power flow decoupling capability in the magnetic medium frequency transformer (MFT). This paper targets to optimize the decoupling between the multiwinding MFT ports by means of multi-objective optimization of the leakage inductance network. Three different multi-objective cost functions are proposed and solved by Genetic Algorithm (GA). The obtained results show that a winding topology where primary winding is sandwiched by the two secondaries and are tightly wound to the core, provides the minimum possible leakage inductance without interleaving the windings. The obtained topologies from solving different objectives can be used as a benchmark in design and manufacturing of mutliwinding transformers. Experimental results are provided to verify the obtained optimum design

Record Efficiency of PhosTop Solar Cells from n-type Cz UMG Silicon Wafers

AbstractHighly purified n-type Upgraded Metallurgical Grade (UMG) silicon carries a large potential for high efficiency low cost solar cells. In this study, the industrially producible “PhosTop” solar cell concept is employed to manufacture large-area n-type rear junction solar cells from such a Si material with a screen-printed Al-alloyed full-area emitter featuring a selective phosphorous front surface field (FSF) and a SiO2/SiNx:H passivation on the front.Since resistivity at the seed end is about seven times as high as at the tail end of the UMG Si ingot and carrier lifetime decreases from seed to tail end, a clear dependence of the solar cells’ IV characteristics on the original position of the corresponding wafers in the UMG Si ingot is observable. Maximum conversion efficiency is reached (on a wafer which has been taken out at about one fifth of the ingot's length distant from the seed end) by η = 19.0% being, to the authors’ knowledge, the highest efficiency so far reported on industrial type solar cells manufactured from 100% UMG Si

JustSTART: How to Find an RSA Authentication Bypass on Xilinx UltraScale(+) with Fuzzing

Fuzzing is a well-established technique in the software domain to uncover bugs and vulnerabilities. Yet, applications of fuzzing for security vulnerabilities in hardware systems are scarce, as principal reasons are requirements for design information access (HDL source code). Moreover, observation of internal hardware state during runtime is typically an ineffective information source, as its documentation is often not publicly available. In addition, such observation during runtime is also inefficient due to bandwidth-limited analysis interfaces (JTAG, and minimal introspection of internal modules). In this work, we investigate fuzzing for 7-Series and UltraScale(+) FPGA configuration engines, the control plane governing the (secure) bitstream configuration within the FPGA. Our goal is to examine the effectiveness of fuzzing to analyze and document the opaque inner workings of FPGA configuration engines, with a primary emphasis on identifying security vulnerabilities. Using only the publicly available chip and dispersed documentation, we first design and implement ConFuzz, an advanced FPGA configuration engine fuzzing and rapid prototyping framework. Based on our detailed understanding of the bitstream file format, we then systematically define 3 novel key fuzzing strategies for Xilinx configuration engines. Moreover, our strategies are executed through mutational structure-aware fuzzers and incorporate various novel custom-tailored, FPGA-specific optimizations. Our evaluation reveals previously undocumented behavior within the configuration engine, including critical findings such as system crashes leading to unresponsive states of the FPGA. In addition, our investigations not only lead to the rediscovery of the starbleed attack but also uncover JustSTART (CVE-2023-20570), capable of circumventing RSA authentication for Xilinx UltraScale(+). Note that we also discuss countermeasures