Reliability of Radiovisiography and Cytomorphometry in Determining the Age of an Individual: A Clinical Comparative Study.

The oral cavity can be explored as an area to identify the impacts of aging. Exfoliative cytology is a painless, rapid, and effective method for collecting intact cells from various epithelial layers for microscopic examination. Therefore, the current study's objective was to determine the average cell size using morphometric analysis and radiovisiography (RVG) to estimate an individual's age utilizing buccal smears and the pulp/tooth ratio. A software program was utilized to determine the cell size using exfoliative cytology, and the pulp and tooth area was measured using RVG of mandibular canine with the help of an image analysis software. Appropriate statistical tests were performed using IBM SPSS statistical software for Windows (version 25). The patient's chronological age, pulp area, and the associated pulp-tooth area ratio values were determined, along with Karl Pearson's correlation coefficient. It was discovered by using a paired t-test to compare chronological age to the age deduced from cell size and pulp-tooth area ratio. According to the current study, age estimation could be done based on average cell size, pulp size, and pulp-tooth area ratio for forensic odontology. Studies with bigger sample sizes and diverse population would help achieve definitive conclusions about the reliability of this particular method.

Shifts of the pond area ratio for lowland polders: Implication for nutrient control.

Shifts for natural ecosystems were increasingly concerned due to its profound impacts on ecosystem services. Ponds within lowland artificial watersheds (polders) play a critical role in nitrogen (N) and phosphorus (P) cycling. From the perspective of N & P control in management practices, it is needed to determine an optimal pond area ratio for polders. For this purpose, our study proposed a process-based modelling framework to investigate the response of polder N & P loss to pond area, and thus to determine the threshold value of pond area ratio to achieve maximum N & P reduction for polders. The proposed framework included two process-based models (NDP and PDP) specially developed to describe N & P dynamics in lowland polders. To evaluate the proposed performance of the framework, it was applied to 171 polders in Zhong River Watershed in Lake Taihu Basin, eastern China. Our investigation results revealed that the correlation between polder N & P reduction rate and pond area ratio had an abrupt shift of 13.6 %, 14.7 % for N & P, respectively. Therefore, polders with a pond area ratio of 13.6-14.7 % had the largest N & P reduction (5.27 and 0.19 kg/ha). Polder size affected P reduction rate, with smaller polders (<200 ha) showing a higher P reduction rate, while it did not affect N reduction rate. Compared with annual precipitation, rainy-season precipitation more significantly (P<0.01) determined polder N & P reduction. This study demonstrated the use of our process-based framework in characterizing the shifts for the pond area ratio for polders, and thus provided technical support for N & P control of lowland areas in water management practices.

Association between the skeletal muscle mass to visceral fat area ratio and metabolic dysfunction-associated fatty liver disease: A cross-sectional study of NHANES 2017-2018.

BACKGROUND AND AIMS: Previous studies have shown that sarcopenic obesity (SO) was associated with nonalcoholic fatty liver disease (NAFLD). However, research is limited in the context of the NAFLD renamed as metabolic dysfunction-associated steatotic liver disease (MASLD) defined by updated diagnostic criteria. The aim of this study was to use the index skeletal muscle mass to visceral fat area ratio (SVR) to describe SO in a large and representative US population (National Health and Nutrition Examination Survey 2017-2018) of adults and investigate their association with MASLD. METHODS: A total of 2087 individuals were included in the analysis. SVR was calculated according to the measurement of dual-energy x-ray absorptiometry and MASLD was diagnosed with controlled attenuation parameter scores and cardiometabolic risk factors. SVR was divided into tertiles. Logistic regression adjusted for confounders was used to evaluate the association between SVR and MASLD. Several sensitivity analyses were performed to test the robustness of our findings. RESULTS: In a multivariate logistic regression analysis, a significant association between SVR and MASLD was shown (odds ratio [OR]: 3.11, 95% confidence interval [CI]: 1.31-7.39, p = .010 for middle levels of SVR; OR: 3.82, 95% CI: 1.45-10.08, p = .007 for lowest levels of SVR). The sensitivity analyses confirmed that the association was robust. CONCLUSION: Our findings imply that decreased SVR is linked to MASLD.

Value of quantitative microsurface structure analysis for evaluating the invasion depth of type 0-II early gastric cancer.

Background and Aim: The microsurface structure reflects the degree of damage to the glands, which is related to the invasion depth of early gastric cancer. To evaluate the diagnostic value of quantitative microsurface structure analysis for estimating the invasion depth of early gastric cancer. Methods: White-light imaging and narrow-band imaging (NBI) endoscopy were used to visualize the lesions of the included patients. The area ratio and depth-predicting score (DPS) of each patient were calculated; meanwhile, each lesion was examined by endoscopic ultrasonography (EUS). Results: Ninety-three patients were included between 2016 and 2019. Microsurface structure is related to the histological differentiation and progression of early gastric cancer. The receiver operating characteristic curve showed that when an area ratio of 80.3% was used as a cut-off value for distinguishing mucosal (M) and submucosal (SM) type 0-II gastric cancers, the sensitivity, specificity, and accuracy were 82.9%, 80.2%, and 91.6%, respectively. The accuracies for distinguishing M/SM differentiated and undifferentiated early gastric cancers were 87.4% and 84.8%, respectively. The accuracy of EUS for distinguishing M/SM early gastric cancer was 74.9%. DPS can only distinguish M-SM1 (SM infiltration <500 µm)/SM (SM infiltration ≥500 µm) with an accuracy of 83.8%. The accuracy of using area ratio for distinguishing 0-II early gastric cancers was better than those of using DPS and EUS (P < 0.05). Conclusion: Quantitative analysis of microsurface structure can be performed to assess M/SM type 0-II gastric cancer and is expected to be effective for judging the invasion depth of gastric cancer.

Significance of the cribriform morphology area ratio for biochemical recurrence in Gleason score 4 + 4 prostate cancer patients following robot-assisted radical prostatectomy.

BACKGROUND: In prostate cancer, histological cribriform patterns are categorized as Gleason pattern 4, and recent studies have indicated that their size and percentage are associated with the risk of biochemical recurrence (BCR). However, these studies included a mixture of cases with various Gleason scores (GSs). We therefore examined the prognostic value of the area and percentage of cribriform patterns in patients with GS 4 + 4 prostate cancer. METHODS: We investigated 108 patients with GS 4 + 4 prostate cancer who underwent robot-assisted radical prostatectomy (RARP). After digitally scanning the hematoxylin and eosin-stained slides, we measured the area of the entire cancer and cribriform patterns. Predictive factors for BCR were explored using log-rank test and Cox proportional hazard model analyses. RESULTS: Sixty-seven (62.0%) patients had a cribriform pattern in RARP specimens, and 32 (29.6%) experienced BCR. The median total cancer area, cribriform pattern area, and percentage of cribriform pattern area (% cribriform) were 427.70 mm2 (interquartile range [IQR], 171.65-688.53 mm2 ), 8.85 mm2 (IQR, 0-98.83 mm2 ), and 2.44% (IQR, 0%-33.70%), respectively. Univariate analyses showed that higher preoperative serum prostate-specific antigen (PSA) levels, positive resection margins, advanced pathological T stage, extraprostatic extension, larger total cancer area, larger cribriform morphology area, and higher % cribriform values were significantly associated with BCR. A multivariate analysis demonstrated that the PSA level (hazard ratio [HR], 1.061; 95% confidence interval [CI], 1.011-1.113; p = 0.017) and % cribriform (HR, 1.018; 95% CI, 1.005-1.031; p = 0.005) were independent predictors of BCR. CONCLUSIONS: An increased % cribriform value was associated with BCR in patients with GS 4 + 4 prostate cancer following RARP.

Study of secondary dentine deposition in central incisors as an age estimation method for adults.

This work aimed to assess the pulp/tooth area ratio's utility in the upper central incisors using orthopantomograms. A convenience sample of 801 adult patient orthopantomograms was studied. Image J® software was used to measure the pulp/tooth area ratio, and a regression model was developed. Our results conclude that the methodology assessing upper incisors' pulp/tooth area ratio using orthopantomograms can lead to age overestimation and statistically significant differences between chronological and estimated age. For those over 50, no correlation between pulp/tooth area ratio and chronological age was found, suggesting that this may be the upper limit of this technique in this population. This methodology may not be suitable for age estimation, particularly in older adults.

Building integrated diffusers' area ratio optimization.

This paper presents an investigation into the effect of area ratio parameter of diffusers on its energy output through power coefficient Cp. This parameter has effect both on diffusers' energy yield, besides diffuser's size for architectural integration prospects. A systematic increase in diffusers area ratio is adopted following standardized diffuser profile presented by NACA 1244 aerofoil. A series of area ratios were investigated (i.e., 1.25, 1.5, 1.75, 2, 2.5, 3 and 3.5). Area ratio of 1.5 (i.e., outlet/inlet, 0.75 m/0.50 m) exhibited the highest power coefficient Cp of 4.2, in addition to achieving highest resulting velocity of 25.8 m/s under incident velocity of 16m/s. Considerable wind separation inside inner walls of diffusers occurred from area ratio 1.75 onwards, which impacted resulting velocities. Simulations performed with ANSYS CFD Academic to standalone diffusers. A series of incident velocities employed from 1 to 16 m/s that resulted in velocity increase by 120-156% respectively.

Computational fluid dynamics for predicting the growth of small unruptured cerebral aneurysms.

OBJECTIVE: Larger cerebral aneurysms are more likely to enlarge, but even small aneurysms can grow. The aim of this study was to investigate the hemodynamic characteristics regarding the growth of small aneurysms using computational fluid dynamics (CFD). METHODS: The authors analyzed 185 patients with 215 unruptured cerebral aneurysms with a maximum diameter of 3-5 mm, registered in a multicenter prospective observational study of unruptured aneurysms (Systematic Multicenter Study of Unruptured Cerebral Aneurysms Based on Rheological Technique at Mie) from January 2013 to February 2022. Based on findings on repeated images, aneurysms were divided into a stable group (182 aneurysms) and a growth group (33 aneurysms). The authors developed the high shear concentration ratio (HSCR), in which high wall shear stress (HWSS) was defined as a value of 110% of the time-averaged wall shear stress of the dome. High shear area (HSA) was defined as the area with values above HWSS, and the ratio of the HSA to the surface area of the dome was defined as the HSA ratio (HSAR). They also created the flow concentration ratio (FCR) to measure the concentration of the inflow jet. Multivariate logistic regression analysis was performed to determine morphological variables and hemodynamic parameters that independently characterized the risk of growth. RESULTS: The growth group had a significantly higher projection ratio (0.74 vs 0.67, p = 0.04) and volume-to-ostium area ratio (1.72 vs 1.44, p = 0.02). Regarding the hemodynamic parameters, the growth group had significantly higher HSCR (6.39 vs 4.98, p < 0.001), lower HSAR (0.28 vs 0.33, p < 0.001), and lower FCR (0.61 vs 0.67, p = 0.005). In multivariate analyses, higher HSCR was significantly associated with growth (OR 0.81, 95% CI 7.06 e-1 to 9.36 e-1; p = 0.004). CONCLUSIONS: HSCR may be a useful hemodynamic parameter to predict the growth of small unruptured cerebral aneurysms.

A Thermodynamic Perspective of Cancer Cells' Volume/Area Expansion Ratio.

The constructal law is used to improve the analysis of the resonant heat transfer in cancer cells. The result highlights the fundamental role of the volume/area ratio and its role in cancer growth and invasion. Cancer cells seek to increase their surface area to facilitate heat dissipation; as such, the tumour expansion ratio declines as malignant cells start to migrate and the cancer expands locally and systemically. Consequently, we deduce that effective anticancer therapy should be based on the control of some ion transport phenomena in an effort to increase the volume/area ratio. This emphasises restricting the local and systemic spatial expansion of the tumour system and thus gives further credence to the superior role of novel anti-migratory and anti-invasive treatment strategies over conventional anti-proliferative options only.

Understanding the Impact of Active-to-Passive Area Ratio on Deformation in One-Dimensional Dielectric Elastomer Actuators with Uniaxial Strain State.

There is increasing interest in the use of novel elastomers with inherent or modified advanced dielectric and mechanical properties, as components of dielectric elastomer actuators (DEA). This requires corresponding techniques to assess their electro-mechanical performance. A common way to test dielectric materials is the fabrication of actuators with pre-stretch fixed by a stiff frame. This results in the problem that the electrode size has an influence on the achievable actuator displacement and strain, which is detrimental to the comparability of experiments. This paper presents an in-depth study of the active-to-passive ratio with the aim of investigating the influence of the coverage ratio on uniaxial actuator displacement and strain. To model the effect, a simple lumped-parameter model is proposed. The model shows that the coverage ratio for maximal displacement is 50%. To validate the model results, experiments are carried out. For this, a rectangular, fiber-reinforced DEA is used to assess the relation of the coverage ratio and deformation. Due to the stiffness of the fibers, highly anisotropic mechanical properties are achieved, leading to the uniaxial strain behavior of the actuator, which allows the validation of the one-dimensional model. To consider the influence of the simplifications in the lumped-parameter model, the results are compared to a hyperelastic model. In summary, it is shown that the ratio of the active-to-passive area has a significant influence on the actuator deformation. Both the model and experiments confirm that an active-to-passive ratio of 50% is particularly advantageous in most cases.

An Exploratory Study of Laser Scribing Quality through Cross-Section Scribing Profiles.

This article presents a novel approach for evaluating laser scribing quality through cross-section profiles generated from a three-dimensional optical profiler. Existing methods for assessing scribing quality only consider the width and depth of a scribe profile. The proposed method uses a cubic spline model for cross-section profiles. Two quality characteristics are proposed to assess scribing accuracy and consistency. Accuracy is measured by the ratio of the actual laser-scribed area to the target area (RA), which reflects the deviation from the desired profile. The mean square error (MSE) is a measure of how close each scribed cross-section under the same scribing conditions is to the fitted cubic spline model. Over 1370 cross-section profiles were generated under 171 scribing conditions. Two response surface polynomial models for RA and MSE were built with 18 scribing conditions with acceptable scribing depth and RA values. Both RA and MSE were considered simultaneously via contour plots. A scatter plot of RA and MSE was then used for Pareto optimization. It was found that the cross-sectional profile of a laser scribe could be accurately represented by a cubic spline model. A multivariate nonlinear regression model for RA and MSE identified pulse energy and repetition rate as the two dominant laser parameters. A Pareto optimization analysis further established a Pareto front, where the best compromised solution could be found.

The relationship between skeletal muscle mass to visceral fat area ratio and metabolic dysfunction-associated fatty liver disease subtypes in middle-aged and elderly population: a single-center retrospective study.

Background: It has been reported that decreased muscle mass combined with excessive visceral adipose tissue are significantly correlated with the risk of non-alcoholic fatty liver disease (NAFLD). However, it has not been explored among populations with metabolic dysfunction-associated fatty liver disease (MAFLD) subtypes. We aimed to investigate whether appendicular skeletal muscle mass to visceral fat area ratio (SVR), an indicator of sarcopenic obesity, influences on the risk of MAFLD subtypes and its hepatic condition in middle-aged and elderly population. Methods: A total of 4,003 middle-aged and elderly subjects were finally enrolled in this single-center retrospective study. Abdominal ultrasonography was employed for hepatic steatosis diagnosis. Participants were divided into four groups: diabetes-MAFLD, overweight/obese-MAFLD, lean-MAFLD and no MAFLD. Appendicular skeletal muscle mass as well as visceral fat area (VAF) was estimated by bioimpedance analysis measurements. Liver fibrosis was defined as a Fibrosis-4 index (FIB-4) and the NAFLD Fibrosis Score (NFS). Multivariate logistic regression analysis was performed to estimate the odds ratio and 95% confidence interval between SVR and MAFLD subtypes/hepatic condition stratified by sex. Results: Participants with MAFLD subtypes had a significant lower value of SVR compared with those without MAFLD (P<0.001), while high quartiles of FIB-4 and NFS also showed a decreasing value of SVR in comparison with its lower quartiles (Pfor trend<0.001). The lowest quartile of SVR increased the prevalence of MAFLD subtypes [adjusted OR (95%CI): 2.96 (1.48 ~ 5.93) male /3.30(1.46 ~ 7.46) female for diabetes-MAFLD, 1.91(1.26 ~ 2.88) male /4.48(1.91 ~ 10.49) female for overweight/obese-MAFLD and 4.01(1.46 ~ 10.98) male/2.53(1.19 ~ 5.37) female for lean-MAFLD groups] compared with the highest quartile of SVR (all Pfor trend<0.001). Besides, the interaction effect of gender on the relationship between SVR and MAFLD subtypes was statistically significant (all Pfor interaction<0.001).Restricted cubic spline indicated an inverse association between SVR and the risk of MAFLD subtypes with linearity (all P for non-linearity>0.05). The lowest quartile of SVR also increases the risk of MAFLD fibrosis in both males and females. Conclusion: Our study concluded that a decrease in SVR (appendicular skeletal muscle mass divided by visceral fat area) is significantly associated with an increased prevalence of developing MAFLD subtypes and liver fibrosis in middle-aged and older persons of both genders.

The correlation between visceral fat/subcutaneous fat area ratio and monocyte/high-density lipoprotein ratio in patients with type 2 diabetes mellitus and albuminuria.

OBJECTIVE: This study aims to observe the correlation between the visceral fat/subcutaneous fat area ratio (VSR) and peripheral blood monocyte/high-density lipoprotein ratio (MHR) in patients with type 2 diabetes mellitus (T2DM) and albuminuria. METHODS: Based on the urinary albumin/creatinine ratio (UACR), 89 T2DM patients were divided into normo-albuminuria group (n = 49, UACR <30 mg/g) and albuminuria group (n = 40, UACR ≥30 mg/g). Gender, age, body mass index (BMI), duration of T2DM, blood pressure, visceral fat area (VA), subcutaneous fat area (SA), biochemical indexes of blood serum and urinary were collected and compared between the two groups, and the relationship between VSR and MHR was analyzed in albuminuria group. RESULTS: No significant differences existed in gender, age, BMI, duration of diabetes, blood pressure, serum lipids, and hemoglobin Alc between the two groups. The levels of VA, VSR, MHR, and UACR were higher in the albuminuria group (P < 0.05). VSR was positively correlated with MHR (r = 0.39, P < 0.01), whereas VA was not significantly correlated with MHR in the albuminuria group. CONCLUSION: Compared with VA, VSR was significantly correlated with MHR, suggesting that VSR is more closely related to the occurrence of chronic inflammation in type 2 diabetics with albuminuria.

Corrigendum: Foliar application of putrescine alleviates terminal drought stress by modulating water status, membrane stability, and yield- related traits in wheat (Triticum aestivum L.).

[This corrects the article DOI: 10.3389/fpls.2022.1000877.].

Algorithm for pediatric orbital blowout fractures: a 20-year retrospective cohort study

Abstract Objective Pediatric orbital blowout fractures can include pathologies that seem mild but require urgent release; serious sequelae can occur with standby surgery or conservative treatment. We sought to validate an algorithm for the treatment of pediatric orbital blowout fractures. Methods This retrospective cohort study included 61 pediatric patients, aged 18 years or younger, treated for pure orbital blowout fractures according to the algorithm from April 1, 2000, to August 31, 2020, at the Japanese Red Cross Asahikawa Hospital. Results There were 52 males (85%). Median age was 14 years (range, 5-18 years). There were 9 patients categorized as needing urgent release, 16 as needing repair, and 36 as needing conservative treatment. Mean follow-up ocular movement was 98.0 (95% Confidence Interval [95% CI], 96.8-99.2). Postoperative diplopia was not observed in 96% (79.6%-99.9%) of patients, better than in previous studies. A higher proportion of patients aged 0-12 years needed urgent repair than those aged 13-18 years (Odds Ratio [OR] = 14.2; 95% CI 1.6-683.4; p= 0.0046). There were no differences in Hess area ratio by age group. Conclusion Clinical results with the algorithm were satisfactory. The algorithm is suitable for treatment of pediatric orbital blowout fractures. Level of evidence 4.

The relationship between false-lumen area ratio and renal replacement therapy after acute aortic dissection repair on bilateral artery cannulation: a cross-sectional study.

Background: Malperfusion poses a serious challenge to organ function in the repair of acute aortic dissection (AAD). The purpose of this study was to explore the segment change of false-lumen area ratio (FLAR; the ratio of the maximal false-lumen area to the total lumen area) in the descending aorta and its relationship with renal replacement therapy (RRT) after total aortic arch (TAA) surgery. Methods: A total of 228 patients with AAD who received TAA using perfusion mode right axillary and femur artery cannulation between March 2013 and March 2022 were included in a cross-sectional study. The descending aorta was divided into 3 segments: the descending thoracic aorta (S1), the abdominal aorta above the ostium of the renal artery (S2), and the abdominal aorta between the ostium of the renal artery and the iliac bifurcation (S3). The primary outcomes were postoperative segmental FLAR changes in the descending aorta, which were observed using computed tomography angiography before the patients were discharged from the hospital. The secondary outcomes were RRT and 30-day mortality. Results: The total potencies in the false lumen were 71.1%, 95.2%, and 88.2% in S1, S2, and S3. The postoperative/preoperative ratio of the FLAR was higher in S2 than that in S1 and S3 (S1: 67%±14%; S2: 80%±8%; S3: 57%±12%; all P values <0.001). For the patients undergoing RRT, there was a higher postoperative/preoperative ratio of the FLAR for the S2 segment (85%±7% vs. 79%±8%; P<0.001) and higher mortality (28.9% vs. 7.7%; P<0.001) after AAD repair compared with patients in the no-RRT group. Conclusions: This study demonstrated there was less attenuation of the FLAR on the abdominal aorta above the ostium of the renal artery in the whole descending aorta after AAD repair with intraoperative right axillary and femur artery perfusion mode. The patients needing RRT were associated with less postoperative/preoperative change of the FLAR and worse clinical outcomes.

Association between Skeletal Muscle Mass-to-Visceral Fat Ratio and Dietary and Cardiometabolic Health Risk Factors among Korean Women with Obesity.

Sarcopenic obesity (SO) is more associated with cardiovascular diseases than sarcopenia or obesity alone. This study aimed to assess the association between the skeletal muscle mass-to-visceral fat area ratio (SVR) and dietary and cardiometabolic health risk factors in obese women. Fifty-nine women aged 19-65 years with BMI values of ≥25 kg/m2 and <32 kg/m2 were included. The SVR was inversely correlated with blood lipids (total cholesterol, ß = -0.369, p = 0.022; low-density lipoprotein cholesterol, ß = -0.326, p = 0.049) and hs-CRP (ß = -0.305, p = 0.043). Among the dietary factors, fatty acid intake (saturated fatty acids (SFA), ß = -0.287, p = 0.044; monounsaturated fatty acids (MUFA), ß = -0.282, p = 0.048; polyunsaturated fatty acids (PUFA), ß = -0.301, p = 0.035) was inversely correlated with the SVR. Conversely, vitamin B6 and B12 intake (vitamin B6, ß = 0.338, p = 0.012; vitamin B12, ß = 0.281, p = 0.024) showed positive associations with the SVR. Individuals with a lower SVR were more likely to have SO and higher blood lipids and inflammatory marker levels. Regarding dietary factors, the SVR increased with vitamin B6 and B12 intake, which was less likely to occur in individuals with SO.

Microplastics pollution in the rivers of a metropolitan city and its estimated dependency on surrounding developed land.

The spatial distribution and abundance of suspected microplastics (SMPs) in the surface water of a metropolitan city, as represented by four Hong Kong rivers, was studied during the dry season. Shing Mun River (SM), Lam Tsuen River (LT), and Tuen Mun River (TM) are located in urbanized areas, and SM and TM are tidal rivers. The fourth river, Silver River (SR) is situated in a rural area. TM had a significantly higher SMP abundance (53.80 ± 20.67 n/L) than the other rivers. The SMP abundance increased from upstream to downstream in non-tidal rivers (LT and SR), but not in tidal rivers (TM and SM), probably due to the tidal influence and a more homogeneous urban development along the tidal rivers. Inter-site differences in the SMP abundance were strongly correlated with the built area ratio (defined as the percentage of surrounding developed land area), human activities, and the nature of the river. About half (48.72 %) of the SMPs were <250 µm. Fibers and fragments were most abundant (>98 %), with most of them being transparent (58.54 %), black (14.68 %), or blue (12.12 %). Polyethylene terephthalate (26.96 %) and polyethylene (20.70 %) were the most common polymers. However, the MP abundance could be overestimated due to the presence of natural fibers. By contrast, an underestimation of the MP abundance could result from a smaller volume of water samples collected, due to a low filtration efficiency caused by high organic content and particle concentrations in the water. A more effective solid waste management strategy and upgrading of the sewage treatment facilities for removing microplastics are recommended to ameliorate the microplastic pollution in local rivers.

The challenge of estimating kelp production in a turbid marine environment.

Coastal kelp forests produce substantial marine carbon due to high annual net primary production (NPP) rates, but upscaling of NPP estimates over time and space remains difficult. We investigated the impact of variable underwater photosynthetically active radiation (PAR) and photosynthetic parameters on photosynthetic oxygen production of Laminaria hyperborea, the dominant NE-Atlantic kelp species, throughout summer 2014. Collection depth of kelp had no effect on chlorophyll a content, pointing to a high photoacclimation potential of L. hyperborea towards incident light. However, chlorophyll a and photosynthesis versus irradiance parameters differed significantly along the blade gradient when normalized to fresh mass, potentially introducing large uncertainties in NPP upscaling to whole thalli. Therefore, we recommend a normalization to kelp tissue area, which is stable over the blade gradient. Continuous PAR measurements revealed a highly variable underwater light climate at our study site (Helgoland, North Sea) in summer 2014, reflected by PAR attenuation coefficients (Kd ) between 0.28 and 0.87 m-1 . Our data highlight the importance of continuous underwater light measurements or representative average values using a weighted Kd to account for large PAR variability in NPP calculations. Strong winds in August increased turbidity, resulting in a negative carbon balance at depths >3-4 m over several weeks, considerably impacting kelp productivity. Estimated daily summer NPP over all four depths was 1.48 ± 0.97 g C · m-2 seafloor · d-1 for the Helgolandic kelp forest, which is in the range of other kelp forests along European coastlines.