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We introduce in this paper the notion of Hodge similarities of transcendental lattices of hyperkähler manifolds and investigate the Hodge conjecture for these Hodge morphisms. Studying K3 surfaces with a symplectic automorphism, we prove the Hodge conjecture for the square of the general member of the first four-dimensional families of K3 surfaces with totally real multiplication of degree two. We then show the functoriality of the Kuga–Satake construction with respect to Hodge similarities. This implies that, if the Kuga–Satake Hodge conjecture holds for two hyperkähler manifolds, then every Hodge similarity between their transcendental lattices is algebraic after composing it with the Lefschetz isomorphism. In particular, we deduce that Hodge similarities of transcendental lattices of hyperkähler manifolds of generalized Kummer deformation type are algebraic.

We study base-point-freeness for big and nef line bundles on hyperkähler manifolds of generalized Kummer type: For n ∈ { 2 , 3 , 4 } , we show that, generically in all but a finite number of irreducible components of the moduli space of polarized Kum n -type varieties, the polarization is base-point-free. We also prove generic base-point-freeness in the moduli space in all dimensions if the polarization has divisibility one.

Athletes frequently compete only a few days after long‐haul travel. Longitudinal real‐world data on athletes’ sleep and sleep–wake cycle in competitive settings remain scarce. This study assessed the impact of a long‐haul travel across ∼13 time zones on sleep patterns, rest–activity circadian rhythms (RAR), and their subsequent effects on neuromuscular function and race performance in the Canadian Short‐Track Speed Skating Team. Nineteen athletes (24 ± 4 years, 11 women) travelled from Montréal (UTC‐5) to Asia (UTC+8, UTC+9) for World Cup races between 2017 and 2019. Actigraphy data were collected before (Baseline) and during travel, during the stay in Asia (SIA), and during competition days. RAR were computed using cosinor analyses on accelerometry data with 24 h phase periods. Countermovement jump height (CMJ) was measured in a subsample (n = 10). Compared to baseline (7:08 ± 0:53), athletes obtained less sleep during travel (6:16 ± 1:27) and competition days (6:35 ± 1:10), and more during SIA (7:32 ± 0:46; time effect P < 0.0001). Sleep efficiency and CMJ were greater in SIA than baseline (P = 0.007 and P = 0.0004, respectively). During SIA, sleep time increased by 9 min per night until the fifth day (P < 0.0001), with a slight decrease in sleep efficiency (P = 0.005) and an increase in CMJ (P < 0.0001). For RAR, mean activity peaked on day 2, shifting from late evening to ∼15:00. Race performance was not different from other races of the same season (P > 0.254). Our results demonstrated that, despite the possible sleep debt from the long‐haul travel, athletes recovered within 5 days, highlighting their adaptability to manage sleep debt and jetlag without impacting competitive outcomes. What is the central question of this study? Which are the effects of long‐haul travel crossing ~13 time zones on sleep, RAR and performance in speed skaters travelling for competitions? What is the main finding and its importance? Total sleep time progressively increased for up to 5 days after landing, along with adjustments in RAR. Neuromuscular performance and competition performance remained unaltered, indicating that any potential impaitments due to travel or jet‐lag were resolved within 5 days.

PurposeTo examined the time-course of the early and late phase of the rate of voluntary force development (RVFD) and muscle damage markers after downhill running.MethodsTen recreational runners performed a 30-min downhill run at 10 km h−1 and −20% (−11.3°) on a motorized treadmill. At baseline and each day up to 4 days RVFD, knee extensors maximum voluntary isometric force (MVIC), serum creatine kinase (CK) concentration, quadriceps swelling, and soreness were assessed. The early (0–50 ms) and late (100–200 ms) phase of the RVFD, as well as the force developed at 50 and 200 ms, were also determined.ResultsMVIC showed moderate decrements (p < 0.05) and recovered after 4 days (p > 0.05). Force at 50 ms and the early phase were not impaired (p > 0.05). Conversely, force at 200 ms and the late phase showed moderate decrements (p < 0.05) and recovered after 3 and 4 days, respectively (p > 0.05). CK concentration, quadriceps swelling, and soreness increased (p < 0.05) were overall fully resolved after 4 days (p > 0.05).ConclusionDownhill running affected the knee extensors RVFD late but not early phase. The RVFD late phase may be used as an additional marker of muscle damage in trail running.

In fencing, it remains unclear whether practice enhances visual‐spatial attention allocation. We explored whether this ability is improved in fencers and if it is related to attack speed and accuracy. Twelve novices (<1 year of experience) and 12 trained epee fencers (18 ± 10 years of experience) visited the laboratory twice (familiarization and testing session). They performed a covert orienting of visuospatial attention test (COVAT) on a computer and an epee test, involving 30 trials of 3 shuttles followed by fast attack phases where the fencers quickly hit a target (randomly proposed out of 8). We measured COVAT reaction time, number of successful target hits, and execution time to hit in the fencing test. We found shorter COVAT reaction time for trained fencers (332 ± 24 ms) versus novices (367 ± 32 ms; p < 0.001). The number of hits was greater for trained fencers (22 ± 3) versus novices (16 ± 3; p < 0.001). ANCOVA showed a difference in execution time at the test (823 ± 73 ms vs. 913 ± 141 ms, p = 0.035). A relationship was found between hits and execution time and between execution time and COVAT reaction time for the trained group (r = 0.62, p = 0.03 and r = 0.70, p = 0.01, respectively) but not in the novice group (r = 0.11, p = 0.72 and r = 0.45, p = 0.14, respectively). Mediation analysis showed that the relationship between execution time and number of hits (ADE: p = 0.008) was not mediated by COVAT reaction time (ACME: p = 0.17). These results evidence the importance of visual‐spatial attention allocation in fencing and evidence differences between novices and trained fencers with important implications for talent development in the early career stage. Highlights This is the first study investigating visual‐spatial attention allocation ability by comparing computer and fencing‐specific tests in trained versus novice epee fencers. Speed and accuracy at the fencing test and reaction time at the computer test were greater for trained epee fencers compared to novices. Only trained epee fencers showed a trade‐off between accuracy and speed of execution at the fencing test. This relationship was not mediated by covert‐orienting attention ability despite a correlation between speed of execution and reaction time at the computer test. These results underline the importance of attention allocation and technical abilities, which could improve independently with practice and play a role in epee fencing performance.

PurposeThe effect of trail running competitions on cost of running (Cr) remains unclear and no study has directly examined the effect of distances in similar conditions on Cr. Accordingly, the aims of this study were to (i) assess the effect of trail running races of 40–170 km on Cr and (ii) to assess whether the incline at which Cr is measured influences changes in Cr.MethodsTwenty trail runners completed races of < 100 km (SHORT) and 26 trail runners completed races of > 100 km (LONG) on similar courses and environmental conditions. Oxygen uptake, respiratory exchange ratio, ventilation, and blood lactate were measured before and after the events on a treadmill with 0% (FLAT) and 15% incline (UH) and Cr was calculated.ResultsCr increased significantly after SHORT but not LONG races. There was no clear relationship between changes in Cr and changes in ventilation or blood lactate. There was a significant correlation (r = 0.75, p < 0.01) between changes in FLAT and UH Cr, and the change in Cr was not affected by the incline at which Cr was measured.ConclusionThe distance of the trail running race, but not the slope at which it is measured, influence the changes in Cr with fatigue. The mechanism by which Cr increases only in SHORT is not related to increased cost of breathing.

Telomere length in peripheral blood leukocytes (PBL-TL) was proposed as a biomarker of cancer risk. Recent scientific evidence suggested PBL-TL plays a diverse role in different cancers. Inconsistent results were obtained on PBL-TL in relation to breast cancer risk and specifically to the presence of BRCA1 and BRCA2 mutations. The aim of the present case-control study was to analyse the correlation between family history of breast cancer or presence of a BRCA mutation and PBL-TL in the hypothesis that TL is a modifier of cancer risk. PBL-TL was measured using the real-time quantitative PCR method in DNA for 142 cases and 239 controls. All the women enrolled were characterized for cancer family history. A subgroup of 48 women were classified for the presence of a BRCA mutation. PBL-TL were summarized as means and standard deviations, and compared by standard analysis of variance. A multivariable Generalised Linear Model was fitted to the data with PBL-TL as the dependent variable, case/control status and presence of a BRCA/VUS mutation as factors, and age in 4 strata as a covariate. Age was significantly associated with decreasing PBL-TL in controls (p = 0.01), but not in BC cases. The telomere length is shorter in cases than in controls after adjusting for age. No effect on PBL-TL of BMI, smoke nor of the most common risk factors for breast cancer was observed. No association between PBL-TL and family history was detected both in BC cases and controls. In the multivariate model, no association was observed between BRCA mutation and decreased PBL-TL. A statistically significant interaction (p = 0.031) between case-control status and a BRCA-mutation/VUS was observed, but no effect was detected for the interaction of cancer status and BRCA or VUS. Our study fails to provide support to the hypothesis that PBL-TL is associated with the risk of hereditary BC, or that is a marker of inherited mutations in BRCA genes.

Thiamine is a crucial cofactor involved in the maintenance of carbohydrate metabolism and participates in multiple cellular metabolic processes. Although thiamine can be obtained from various food sources, some common food groups are deficient in thiamine, and it can be denatured by high temperature and pH. Additionally, different drugs can alter thiamine metabolism. In addition, the half-life of thiamine in the body is between 1 and 3 weeks. All these factors could provide an explanation for the relatively short period needed to develop thiamine deficiency and observe the consequent clinical symptoms. Thiamine deficiency could lead to neurological and cardiological problems. These clinical conditions could be severe or even fatal. Marginal deficiency too may promote weaker symptoms that might be overlooked. Patients undergoing upper gastrointestinal or pancreatic surgery could have or develop thiamine deficiency for many different reasons. To achieve the best outcome for these patients, we strongly recommend the execution of both an adequate preoperative nutritional assessment, which includes thiamine evaluation, and a close nutritional follow up to avoid a nutrient deficit in the postoperative period.

PurposeThis study aimed to evaluate the acute changes in the knee extensors maximum voluntary isometric contraction force (MVIC), rate of force development (RFD), and rate of EMG rise (RER) following a bout of downhill running.MethodsMVIC and RFD at 0–50, 50–100, 100–200, and 0–200 ms were determined in thirteen men (22 ± 2 yr) before and after 30 min of downhill running (speed: 10 km h−1; slope: − 20%). Vastus lateralis maximum EMG (EMGmax) and RER at 0–30, 0–50, and 0–75 ms were also recorded.ResultsMVIC, RFD0–200, and EMGmax decreased by ~ 25% [Cohen’s d = − 1.09 (95% confidence interval: − 1.88/− 0.24)], ~ 15% [d = − 0.50 (− 1.26/0.30)], and ~ 22% [d = − 0.37 (− 1.13/0.42)] (all P < 0.05), respectively. RFD100–200 was also reduced [− 25%; d = − 0.70 (− 1.47/0.11); P < 0.001]. No change was observed at 0–50 ms and 50–100 ms (P ≥ 0.05). RER values were similar at each time interval (all P > 0.05).ConclusionDownhill running impairs the muscle capacity to produce maximum force and the overall ability to rapidly develop force. No change was observed for the early phase of the RFD and the absolute RER, suggesting no alterations in the neural mechanisms underlying RFD. RFD100–200 reduction suggests that impairments in the rapid force-generating capacity are located within the skeletal muscle, likely due to a reduction in muscle–tendon stiffness and/or impairments in the muscle contractile apparatus. These findings may help explain evidence of neuromuscular alterations in trail runners and following prolonged duration races wherein cumulative eccentric loading is high.

Genomic testing expansion is accompanied by an increasing need for genetic counselling and intrafamilial communication. Genetic counselling can play an important role in facilitating intrafamilial communication and relationships. We conducted a cross-sectional, multicenter study including 252 Italian women, using a questionnaire divided in two sections, the first one to be filled after the pre-test counselling and the second after receiving BRCA test results. We assessed the factors influencing intrafamilial disclosure of genetic information for hereditary breast and ovarian cancer, family members with whom probands are more prone to share genetic information, and the perceived understanding of information received by counselees during genetic counselling. Women were accompanied to the counselling more often by their husband/partner. Among those with a positive BRCA test result, 49% intended to communicate it to their offspring and 27% to their husband/partner. Younger women, those living with their husband/partner, and those who described family communication as open/profound and spontaneous/sincere had a higher probability of being accompanied during genetic counselling and discuss about it with relatives. Spontaneous/sincere or open/profound family communication and joyful/happy familial relationships were associated with the decision to undergo genetic testing as a responsibility towards relatives. Women had a good understanding of counselling contents (mean score 9.27 in a scale 1–10). Genetic counselling providers should consider that genetic information disclosure does not depend only on the clarity of the information provided, but also on pre-existing intrafamilial communication and relationships, family structure and marital status, indicating the need for a personalised approach accounting for these factors.