Mental Health and Loneliness in University Students During the COVID-19 Pandemic in Germany: A Longitudinal Study

The COVID-19 pandemic and its preventive measures had adverse consequences for mental health. However, knowledge of mental health trajectories across the pandemic is limited. This study investigated the mental health levels and changes among university students during the pandemic and lockdown in Germany, as well as their associated factors. We surveyed students' mental health (N = 363, 68% female) with the patient health questionnaire (PHQ-8) and the generalized anxiety disorder scale (GAD-7) during the first easing phase (July 2020; time 1) and the second lockdown (November 2020; time 2). Cut-off scores from the GAD-7 and PHQ-8 were used to determine clinically relevant symptoms and to define trajectory groups. Sociodemographic and pandemic-related data were assessed (e.g., coping with academic life, social contacts) as well as loneliness, stress, repetitive negative thinking, quality of life, and perceived social support. Paired t-test, multiple regression, and repeated-measures ANOVA were applied. Means and prevalence rates for symptoms of depression (38.8%) and anxiety (25.6%) did not differ between time 1 and time 2, and most students were asymptomatic on the PHQ-8 (44.4%) and the GAD-7 (56.3%) across the pandemic. Feelings of loneliness significantly increased from time 1 to time 2, d = -0.30, [-0.47, -0.13], with higher symptom levels in symptomatic groups at time 2 and greater increases in the asymptomatic groups. Levels of stress, repetitive negative thinking, quality of life, and social support did not differ during the pandemic. At time 1, loneliness and repetitive negative thinking were associated with anxiety and depressive symptoms. Anxiety and depressive symptoms were prevalent among students, and increased levels of loneliness during the pandemic were associated with elevated symptoms and differing trajectories. Further research using representative and larger samples should determine the long-term impact of the pandemic on mental health and loneliness to identify vulnerable students and offer adequate support

Context-Aware Parameter Estimation for Forecast Models in the Energy Domain

Continuous balancing of energy demand and supply is a fundamental prerequisite for the stability and efficiency of energy grids. This balancing task requires accurate forecasts of future electricity consumption and production at any point in time. For this purpose, database systems need to be able to rapidly process forecasting queries and to provide accurate results in short time frames. However, time series from the electricity domain pose the challenge that measurements are constantly appended to the time series. Using a naive maintenance approach for such evolving time series would mean a re-estimation of the employed mathematical forecast model from scratch for each new measurement, which is very time consuming. We speed-up the forecast model maintenance by exploiting the particularities of electricity time series to reuse previously employed forecast models and their parameter combinations. These parameter combinations and information about the context in which they were valid are stored in a repository. We compare the current context with contexts from the repository to retrieve parameter combinations that were valid in similar contexts as starting points for further optimization. An evaluation shows that our approach improves the maintenance process especially for complex models by providing more accurate forecasts in less time than comparable estimation methods

Cortisol response to traumatic stress to predict PTSD symptom development – a systematic review and meta-analysis of experimental studies

Background: Pre-and post-traumatic hypothalamic–pituitary–adrenal (HPA) axis markers have been studied to predict posttraumatic stress disorder (PTSD) risk, but its acute reactivity cannot be measured in real-life settings. Experimental paradigms can depict the cortisol response to stimuli that simulate traumatic events. Objective: To review experimental studies on the cortisol response to traumatic stimuli and the correlation between cortisol and PTSD symptoms. Method: Experimental, (un-)published studies in German or English from any year were eligible if they confronted non-traumatized humans with traumatic stimuli, assessed cortisol before, during or after stimulus presentation and subsequent PTSD symptoms. The literature was searched via PubMed, PubPsych, PsychINFO, PsycArticle, Web of Science, EMBASE, ProQuest and ClinicalTrials.gov up to 16th February 2021. Risk of bias was assessed with the Cortisol Assessment List. Multilevel-meta-analyses were conducted under the random effects model. The standardized mean change (dSMC) indicated the cortisol response. Coefficient r indicated the correlations between cortisol and PTSD symptoms. Results: 14 studies, investigating 1004 individuals, were included. A cortisol response was successfully induced between 21 and 40 min post-presentation onset (kobservations = 25, dSMC = 0.15 [.03; .26]). Cortisol was not associated with overall or cluster-level PTSD symptoms. On a symptom-level, higher pre-presentation onset cortisol was correlated with lower state tension (k = 8, r = −.18 [−.35; −.01]), higher state happiness (k = 8, r = −.34 [−.59; −.03], variable inverted) and lower state anger (k = 9, r = −.14 [−.26; −.01]). Higher post-presentation onset cortisol was correlated with higher state happiness (k = 16, r = −.20 [−.33; −.06]) and lower state sadness (k = 17, r = −.16 [−.25; −.05]), whereas cortisol response was positively correlated with state anxiety (k = 9, r = .16 [0.04; 0.27]). Conclusions: Experimental paradigms effectively induce a cortisol response. Higher basal cortisol, higher cortisol, as measured after traumatic stimulus presentation, and a lower cortisol response were associated with more adaptive emotional reactions. These markers did not predict longer-term PTSD symptoms

Evaluation of methods for measuring tool-chip contact length in wet machining using different approaches (microtextured tool, in-situ visualization and restricted contact tool)

The contact length is one of the most important factors to evaluate the chip formation process and the mechanical loads in metal cutting. Over the years, several methods to identify the contact length were developed. However, especially for wet cutting processes the determination of the contact length is still challenging. In this paper, three methods to identify the contact length for dry and wet processes in cutting of Ti6Al4V and AISI4140 + QT are presented, discussed and analyzed. The first approach uses tools with a microtextured rake face. By evaluating the microstructures on the chip, a new method to identify the contact length is established. The second approach applies high speed recordings to identify the contact length. The challenge is thereby the application of high-speed recordings under wet conditions. In the third approach, tools with restricted contact length are used. It is shown that with all three methods the contact length is reduced using metal working fluid

Enzymatic C–C-Coupling Prenylation: Bioinformatics – Modelling – Mechanism – Protein-Redesign – Biocatalytic Application

The functional role of isoprenoids and especially enzymatic prenylation in nature and human application is briefly covered, with the focus on bioinformatical, mechanistical and structural aspects of prenyltransferases and terpene synthases. These enzymes are as yet underrepresented but perspectively useful biocatalysts for C–C couplings of aromatic and isoprenoid substrates. Some examples of the successful use in chemoenzymatic synthesis are given including an application for the otherwise difficult synthesis of Kuhistanol A. Computational structure-based site-directed mutagenesis can be used for rational enzyme redesign to obtain altered substrate and product specificities, which is demonstrated for terpene cyclases

Impact of Sparse Benthic Life on Seafloor Roughness and High-Frequency Acoustic Scatter

Quantitative acoustic marine habitat mapping needs to consider the impact of macrobenthic organisms on backscatter data. However, the sensitivity of hydroacoustic systems to epibenthic life is poorly constrained. This study explores the impact of a benthic community with sparse abundance on seafloor microroughness and acoustic backscatter at a sandy seafloor in the German North Sea. A multibeam echo sounder survey was ground-truthed by lander measurements combining a laser line scanner with sub-mm resolution and broad-band acoustic transducers. Biotic and abiotic features and spatial roughness parameters were determined by the laser line scanner. At the same locations, acoustic backscatter was measured and compared with an acoustic scatter model utilizing the small-roughness perturbation approximation. Results of the lander experiments show that a coverage with epibenthic features of 1.6% increases seafloor roughness at spatial wavelengths between 0.005–0.03 m, increasing both spectral slope and intercept. Despite the fact that a strong impact on backscatter was predicted by the acoustic model based on measured roughness parameters, only a minor (1.1 dB) change of backscatter was actually observed during both the lander experiments and the ship-based acoustic survey. The results of this study indicate that benthic coverage of less than 1.6% is insufficient to be detected by current acoustic remote sensing

Glycolytic Shunts Replenish the Calvin-Benson-Bassham Cycle as Anaplerotic Reactions in Cyanobacteria

The recent discovery of the Entner-Doudoroff (ED) pathway as a third glycolytic route beside Embden-Meyerhof-Parnas (EMP) and oxidative pentose phosphate (OPP) pathway in oxygenic photoautotrophs requires a revision of their central carbohydrate metabolism. In this study, unexpectedly, we observed that deletion of the ED pathway alone, and even more pronounced in combination with other glycolytic routes, diminished photoautotrophic growth in continuous light in the cyanobacterium Synechocystis sp. PCC 6803. Furthermore, we found that the ED pathway is required for optimal glycogen catabolism in parallel to an operating Calvin–Benson–Bassham (CBB) cycle. It is counter-intuitive that glycolytic routes, which are a reverse to the CBB cycle and do not provide any additional biosynthetic intermediates, are important under photoautotrophic conditions. However, observations on the ability to reactivate an arrested CBB cycle revealed that they form glycolytic shunts that tap the cellular carbohydrate reservoir to replenish the cycle. Taken together, our results suggest that the classical view of the CBB cycle as an autocatalytic, completely autonomous cycle that exclusively relies on its own enzymes and CO2 fixation to regenerate ribulose-1,5-bisphosphate for Rubisco is an oversimplification. We propose that in common with other known autocatalytic cycles, the CBB cycle likewise relies on anaplerotic reactions to compensate for the depletion of intermediates, particularly in transition states and under fluctuating light conditions that are common in nature

Biomechanical evaluation of combined short segment fixation and augmentation of incomplete osteoporotic burst fractures

Background: Treating traumatic fractures in osteoporosis is challenging. Multiple clinical treatment options are found in literature. Augmentation techniques are promising to reduce treatment-related morbidity. In recent years, there have been an increasing number of reports about extended indication for augmentation techniques. However, biomechanical evaluations of these techniques are limited. Methods: Nine thoracolumbar osteoporotic spinal samples (4 FSU) were harvested from postmortem donors and immediately frozen. Biomechanical testing was performed by a robotic-based spine tester. Standardized incomplete burst fractures were created by a combination of osteotomy-like weakening and high velocity compression using a hydraulic material testing apparatus. Biomechanical measurements were performed on specimens in the following conditions: 1) intact, 2) fractured, 3) bisegmental instrumented, 4) bisegmental instrumented with vertebroplasty (hybrid augmentation, HA) and 5) stand-alone vertebroplasty (VP). The range of motion (RoM), neutral zone (NZ), elastic zone (EZ) and stiffness parameters were determined. Statistical evaluation was performed using Wilcoxon signed-rank test for paired samples (p = 0.05). Results: Significant increases in RoM and in the NZ and EZ (p < 0.005) were observed after fracture production. The RoM was decreased significantly by applying the dorsal bisegmental instrumentation to the fractured specimens (p < 0.005). VP reduced fractured RoM in flexion but was still increased significantly (p < 0.05) above intact kinematic values. NZ stiffness (p < 0.05) and EZ stiffness (p < 0.01) was increased by VP but remained lower than prefracture values. The combination of short segment instrumentation and vertebroplasty (HA) showed no significant changes in RoM and stiffness in NZ in comparison to the instrumented group, except for significant increase of EZ stiffness in flexion (p < 0.05). Conclusions: Stand-alone vertebroplasty (VP) showed some degree of support of the anterior column but was accompanied by persistent traumatic instability. Therefore, we would advocate against using VP as a stand-alone procedure in traumatic fractures. HA did not increase primary stability of short segment instrumentation. Some additional support of anterior column and changes of kinematic values of the EZ may lead one to suppose that additive augmentation may reduce the load of dorsal implants and possibly reduce the risk of implant failure.<br