Strong Variations Research Articles

84 Advances, Challenges and Prospects for the Sustainable Use of the chigüiro in Colombia

Abstract The sustainable use of chigüiro or capybara is a strategy proposal to prevent the decline of the species population by maintaining and conserving appropriate habitats, reducing illegal capture, promoting its recognition, and achieving a better distribution of its benefits and its environmental services. The objective of this work is to present the progress made toward the sustainable use of capybaras in Colombia. The biological information compiled during the last 15 years indicates that the density of the populations of this species is heterogeneous throughout the flooded savannahs with space-time variations between < 1 individual/ha, and up to 6 individual/ha. These variations are associated with strong climatic variations, changes in habitat quality, and the impact of a series of conditioning factors, both natural (water availability over time) and anthropogenic origin (hunting, land use, eventual competition with cattle, and the incidence of burning). Commercial hunting as a sustainable strategy includes the identification of various products and by-products of the species, as well as its linkage in Bioeconomy projects (Figure 1) through the compliance of associated normative, the reinforcement of environmental authorities, an effective communication strategy and user commitment. Capybara meat is characterized by having a low-fat content and a protein ratio greater than 20%; and its carcass meat performance is between 44% and 53%. In addition to the training in the preparation of various meat by-products and the analysis and processing of the fur, there is an updated market study that includes an interview phase, a pilot test of exploitation, yields and tastings for approach to the actor of the commercial chain and meet future investors or buyers. With these results, a financial model was formulated with all the necessary costs to make use of the Chigüiro products. Additionally, a prototype processing plant was designed and it has three mobile components (A, B, C); two complementary fixed structures (D, E) and a module for the processing of by-products and waste (Figure 2). Finally, linking capybara population concentration points within ecotourism activities will expand the options for its use and conservation of the Chigüiro population and its habitats. Among the actual limitations for Chigüiro use we have the delay in issuing the resolution for the allocation of the global utilization quota, and the modification of the closure to increase the period of use. These resolutions will encourage the participation of other users and local investors, which is expected to reduce the transformation of natural ecosystems and their associated biodiversity.

An Investigation of New Brown Dwarf Spectral Binary Candidates From the Backyard Worlds: Planet 9 Citizen Science Initiative

We present three new brown dwarf spectral-binary candidates: CWISE J072708.09−360729.2, CWISE J103604.84−514424.4, and CWISE J134446.62−732053.9, discovered by citizen scientists through the Backyard Worlds: Planet 9 project. Follow-up near-infrared spectroscopy shows that each of these objects is poorly fit by a single near-infrared standard. We constructed binary templates and found significantly better fits, with component types of L7+T4 for CWISE J072708.09−360729.2, L7+T4 for CWISE J103604.84−514424.4, and L7+T7 for CWISE J134446.62−732053.9. However, further investigation of available spectroscopic indices for evidence of binarity and large amplitude variability suggests that CWISE J072708.09−360729.2 may instead be a strong variability candidate. Our analysis offers tentative evidence and characterization of these peculiar brown dwarf sources, emphasizing their value as promising targets for future high-resolution imaging or photometric variability studies.

A Comparison of Atmospheric Boundary Layer Height Determination Methods Using GNSS Radio Occultation Data

The accurate determination of Atmospheric Boundary Layer Height (ABLH) is crucial in various atmospheric studies and practical applications. In this study, we present a comprehensive comparative analysis of five distinct methods for estimating ABLH using Global Navigation Satellite System (GNSS) Radio Occultation (RO) data. These methods encompass the use of bending angle and refractivity profiles, namely Minimum Gradient methods of the Bending Angle (MGBA) and Refractivity (MGR) profiles, breaking point, Wavelet Covariance Transform (WCT), and Double-Parameter Model Function (DPMF). GNSS-RO data from COSMIC-2 and Spire are used. To establish robust validation, radiosonde data are employed as a reference, ensuring the reliability of our findings. The results reveal notable variations in the performances of these ABLH estimation methods. Specifically, the MGBA, MGR, breaking point, and DPMF methods exhibit strong correlations with the reference data. Conversely, the WCT method displays weaker correlations, higher biases, and elevated root-mean-square-errors, suggesting limitations in capturing the true ABLH. Furthermore, we remove outlier screening to facilitate a comparison of the differences among the five methods. The WCT and DPMF methods can detect strong variations in the profiles near the Earth’s surface and consider them as ABLH. However, these variations are caused by errors. The MGBA method emerges as a reliable and stable option, while the WCT and DPMF methods should be used with caution due to the lower quality of the GNSS-RO profiles near the Earth’s surface.

Evaluation and Projection of Gale Events in North China

As an important weather extreme, gales greatly impact the air quality, agriculture, aviation, and renewable energy in North China. However, the spatial–temporal changes in gale events remain unknown in North China. In this study, using the ERA5 reanalysis with high spatiotemporal resolution and multi-model simulations from the Coupled Model Intercomparison Project Phase Six (CMIP6), we investigate the temporal changes, including daily, seasonal and decadal variations in gale events in North China between 1980 and 2021, and we project the changes in gale events in the mid and late 21st century under two shared socio-economic pathways (SSPs). The gale events show large spatial heterogeneity in frequency, with a high frequency of >25 days/year in central Inner Mongolia province, northern Hebei province, and northwestern Beijing. Over the past four decades, the gale events in North China have shown a decadal reversal, with a decrease between 1980 and 2006 and an increase between 2007 and 2014. Furthermore, the gale events show strong temporal variations in North China. For seasonal variation, the gale events exhibit double peaks, with the largest peak in April and the smallest peak in October. For daily variation, the gale events show a single peak, with the maximum from 10:00 to 16:00 local time in North China. Multi-model simulations from CMIP6 reveal a continuous decreasing trend of gale events in North China by the end of the 21st century under both SSP1-2.6 and SSP2-4.5 scenarios relative to the historical period. Our results provide comprehensive support for planning aviation, renewable energy, and agriculture in the future.

Functional diversity of microbial eukaryotes in a meromictic lake: Coupling between metatranscriptomic and a trait-based approach.

The advent of high-throughput sequencing has led to the discovery of a considerable diversity of microbial eukaryotes in aquatic ecosystems, nevertheless, their function and contribution to the trophic food web functioning remain poorly characterized especially in freshwater ecosystems. Based on metabarcoding data obtained from a meromictic lake ecosystem (Pavin, France), we performed a morpho-physio-phenological traits-based approach to infer functional groups of microbial eukaryotes. Metatranscriptomic data were also analysed to assess the metabolic potential of these groups across the diel cycle, size fraction, sampling depth, and periods. Our analysis highlights a huge microbial eukaryotic diversity in the monimolimnion characterized by numerous saprotrophs expressing transcripts related to sulfur and nitrate metabolism as well as dissolved and particulate organic matter degradation. We also describe strong seasonal variations of microbial eukaryotes in the mixolimnion, especially for parasites and mixoplankton. It appears that the water mixing (occurring during spring and autumn) which benefits photosynthetic host communities also promotes parasitic fungi dissemination and over-expression of genes involved in the zoospore phototaxis and stage transition in the parasitic cycle. Mixoplanktonic haptophytes over-expressing photosynthesis-, endocytosis- and phagosome-linked genes under nutrient limitation also suggest that phagotrophy may provide them an advantage over non-phagotrophic phytoplankton.

Neural network enhanced aging time measurements of diary product remaining with infrared spectroscopy

The determination of the drying degree of food residues on surfaces is an important step before efficient cleaning can be achieved. To accomplish this goal, a rapid evaluation based on a neural network and non-invasive measurement technique is introduced. Two common starch-based products and various yogurts from different manufacturers are used as example contaminants to determine the aging time of dried food residue. Near-infrared spectroscopy serves as a modern and fast measurement technique for investigating food compositions. Two analysis methods were compared for processing the measured near-infrared spectral data. The raw data were analyzed using partial least squares regression in conjunction with necessary preprocessing steps. As an alternative method, three different types of neural networks are employed. The aim of this approach is to compensate for the filtering steps before regression, which are typically necessary for multivariate regression. The challenge is to measure three different types of food and obtain a reliable prediction of moisture content in order to draw conclusions about the drying time. The experiments have shown that simple flat neural networks have similar accuracy compared to conventional regression. The use of a convolutional layer in advance demonstrates a significant improvement in prediction compared to other neural networks and even manages to surpass the accuracy of PLS regression. A network with a convolutional layer can also compensate for the sometimes strong variations between food types.

Environmental DNA biomonitoring in biodiversity hotspots: A case study of fishes of the Okavango Delta

AbstractThe Okavango Delta is the largest freshwater wetland in southern Africa and a recognized biodiversity hotspot and UNESCO World Heritage Site. The region is extremely rich in floral and faunal diversity, including a fish fauna of ~90 species in 15 families, that also support recreational and subsistence fishing. Anthropogenic pressures and invasive species threaten the unique biodiversity and ecosystem services that the Delta provides, necessitating biomonitoring tools that can provide broad community‐level diversity insights. Here, we utilize environmental DNA metabarcoding of aquatic eDNA using the MiFish 12S rRNA primers, to investigate fish communities and also sequenced 211 mtDNA 12S barcodes for 74 species across 36 genera of fishes from the region. Metabarcoding recovered 11 of 15 families, with 40 species detected across 23 genera, representing ~50% of known diversity, with the mtDNA 12S fragment able to delineate all genera (except for the cichlid genera Serranochromis and Pharyngochromis that comprised a single clade) and most species, except for some in the Clarias, Enteromius, Labeo, Lacustricola, and Petrocephalus genera. Generally, abundant and wide‐spread taxa such as Clarias spp. and Marcusenius altisambesi, amongst others, were often detected in the surveys, with other species, including Zaireichthys kavangoensis, Schilbe intermedius, and Labeo sp. detected less frequently. Dissolved oxygen, temperature, and dissolved organic solids were positively correlated with community diversity, highlighting the influence of environmental factors in shaping fish communities in the region. Further, there was strong variability in the eDNA signal across only 1000 m, suggesting that future surveys need to consider spatio‐temporal aspects of sample collection. Our study highlights the potential of eDNA metabarcoding for surveying aquatic biodiversity in the Okavango Delta, particularly within the context of baseline biodiversity inventories, that underpin conservation and management initiatives. As such, we provide a number of recommendations that can help structure future sampling efforts in the region.

Moored Observations of the West Greenland Coastal Current along the Southwest Greenland Shelf

Abstract We present the first continuous mooring records of the West Greenland Coastal Current (WGCC), a conduit of fresh, buoyant outflow from the Arctic Ocean and the Greenland Ice Sheet. Nearly two years of temperature, salinity, and velocity data from 2018 to 2020 demonstrate that the WGCC on the southwest Greenland shelf is a well-formed current distinct from the shelfbreak jet but exhibits strong chaotic variability in its lateral position on the shelf, ranging from the coastline to the shelf break (50 km offshore). We calculate the WGCC volume and freshwater transports during the 35% of the time when the mooring array fully bracketed the current. During these periods, the WGCC remains as strong (0.83 ± 0.02 Sverdrups; 1 Sv ≡ 106 m3 s−1) as the East Greenland Coastal Current (EGCC) on the southeast Greenland shelf (0.86 ± 0.05 Sv) but is saltier than the EGCC and thus transports less liquid freshwater (30 × 10−3 Sv in the WGCC vs 42 × 10−3 Sv in the EGCC). These results indicate that a significant portion of the liquid freshwater in the EGCC is diverted from the coastal current as it rounds Cape Farewell. We interpret the dominant spatial variability of the WGCC as an adjustment to upwelling-favorable wind forcing on the West Greenland shelf and a separation from the coastal bathymetric gradient. An analysis of the winds near southern Greenland supports this interpretation, with nonlocal winds on the southeast Greenland shelf impacting the WGCC volume transport more strongly than local winds over the southwest Greenland shelf.

Seasonal and Elevational Variability in Dwarf Birch VOC Emissions in Greenlandic Tundra

AbstractRising temperatures amplify biogenic volatile organic compound (VOC) emissions from Arctic vegetation, causing feedbacks to the climate system. Changes in climate also alter plant physiology and vegetation composition, all of which can influence VOC emissions. Moreover, leaf development and biotic stresses cause highly variable emissions during the growing season. Therefore, linking VOC emissions with plant traits and tracking responses to climate change might provide better understanding of VOC emission regulation under future conditions. We measured VOC emissions and other plant traits in dwarf birch (Betula glandulosa) at two elevations in Narsarsuaq, South Greenland. The measurements were performed in warming experiments that have run since 2016. We collected VOCs using the branch enclosure method from early June until late July 2019 (n = 200). Emissions of green leaf volatiles (GLVs), oxygenated monoterpenes (oMTs), and homoterpenes followed a seasonal trend. VOC emission rates and the diversity of the VOC blend decreased at the end of the measurement period. Differences in VOC emission rates between elevations were pronounced early in the season. Majority of the traits did not explain the variation in VOC emissions. We show strong seasonal variability in VOC emissions within the growing season, which is likely driven by leaf phenology. While the diversity of VOCs was greater at the milder low‐elevation site, VOC emission rates were higher or similar at the harsher high‐elevation site, showing stronger VOC emission potentials than previously assumed. Seasonal variations in the emissions of VOCs are crucial for accurate predictions of current and future VOC emissions from arctic ecosystems.

Potentially Inappropriate Medication Dispensing in Outpatients: Comparison of Different Measurement Approaches.

This paper aims at comparing different approaches to measure potentially inappropriate medication (PIM) with routinely collected data on prescriptions, patient age institutionalization status (ie in nursing home or in the community). A secondary objective is to measure the rate and prevalence of PIM dispensing and to identify problematic practices in Switzerland. The studied population includes about 90,000 insured over 17 years old from a Swiss health maintenance organization in 2019 and 2020. We computed and compared the number of PIM per patient for Beers criteria, Priscus list, Laroche, NORGEP and Prescrire approaches. We also created a composite indicator that accounts for the specificities of the Swiss context (adaptation to the Swiss drugs' market, recommendations in force related to sleeping pills, anxiolytics and NSAIDs). We also stratified the analysis per physician, including initiation and cessation of PIM prescription. Our comparison revealed similarities between the approaches, but also that each of them had specific gaps that provides further motivation for the development of a composite approach. PIM rate was particularly high for sleeping pills, anxiolytics, NSAIDs, even when analyses were limited to chronic use. Drugs with anticholinergic effect were also frequently prescribed. Based on our composite indicator, 27% of insured over 64 years old received at least one PIM in 2020, and 8% received more than one. Our analyses also reveal that for sleeping pills and anxiolytics, half of the volume (or prevalence?) occurs in the <65 population. We observed strong variations between physicians and a significant proportion of new users among patients with PIM. Our results show that PIMs prescribing is very frequent in Switzerland and is driven mostly by a few drug categories. There is important physician variation in PIM prescribing that warrants the development of intervention targeted at high PIM-prescribers.

Event-triggered model predictive tracking control of aero-engine with varying prediction horizon

Aero-engine is a complex thermal-mechanical system with strong nonlinearity, uncertainty, and time variation. Thus, it is crucial to design an effective controller for such a complex system to obtain the desired performances of the aero-engine. In recent years, model predictive control (MPC) has shown great potential in dealing with control problems with complex constraints of multi-variable systems, which has been applied to aero-engine control, achieving good results. Furthermore, the MPC strategy using an event-driven mechanism is good at balancing system resources and ensuring system control performances. In this paper, the problem of event-triggered MPC for aero-engine systems with bounded disturbances is studied. Firstly, an event-triggered strategy with a dynamic forced-trigger mechanism is proposed. Then, an MPC algorithm based on an event-triggered mechanism is designed. Finally, an application to the JT9D aero-engine model provided by T-MATS verifies the effectiveness of the designed algorithm. It is shown that the calculation load is significantly reduced, which proves the superiority of this method.

Deep Short‐Term Slow Slip and Tremor in the Manawatu Region, New Zealand

AbstractThe Manawatu region experiences deep tremor and long‐term slow slip events (SSEs); however, tremor is adjacent to, and not co‐located with, long‐term SSEs. Observations of episodic tremor and slip (ETS) elsewhere suggest it is possible smaller short‐term SSEs below the current detection threshold occur where tremor is observed. Therefore, we sought to determine if small SSEs occurred with Manawatu tremor. We decomposed GNSS data using times of tremor to assess average surface displacements and performed a static slip inversion to model the displacement during tremor. The slip inversion suggested small slow slip partially coincided with tremor and long‐term SSEs may influence these small SSEs by increasing slip rates. We suggest that the interface below deep long‐term SSEs may slip often, in small ETS‐like SSEs that are not individually detectable geodetically. The question remains as to the nature of the strong variability in SSE behavior with depth and duration in the southern Hikurangi margin.

VoroNoodles: Topological Interlocking with Helical Layered 2‐Honeycombs

An approach for modeling topologically interlocked building blocks that can be assembled in a water‐tight manner (space filling) to design a variety of spatial structures is introduced. This approach takes inspiration from recent methods utilizing Voronoi tessellation of spatial domains using symmetrically arranged Voronoi sites. Attention is focused on building blocks that result from helical stacking of planar 2‐honeycombs (i.e., tessellations of the plane with a single prototile) generated through a combination of wallpaper symmetries and Voronoi tessellation. This unique combination gives rise to structures that are both space‐filling (due to Voronoi tessellation) and interlocking (due to helical trajectories). Algorithms are developed to generate two different varieties of helical building blocks, namely, corrugated and smooth. These varieties result naturally from the method of discretization and shape generation and lead to distinct interlocking behavior. In order to study these varieties, finite‐element analyses (FEA) are conducted on different tiles parametrized by 1) the polygonal unit cell determined by the wallpaper symmetry and 2) the parameters of the helical line generating the Voronoi tessellation. Analyses reveal that the new design of the geometry of the building blocks enables strong variation of the engagement force between the blocks.

Nanoparticles of poly(3-hexylthiophene): Toward a solvent-independent performance of electrochromic films

Nanoparticles of poly(3-hexylthiophene), P3HT(NP), uniquely enable the preparation of stable dispersions in environmentally-friendly media and thus offer a sustainable liquid phase fabrication of electrochromic device structures. In this work, we assess the electrochromic performance of P3HT(NP) films spray-coated from either tetrahydrofuran (THF)-water or chloroform (CHCl3)-ethanol dispersions on ITO substrates. The nanoparticle films exhibit consistent and reproducible high optical contrast values of around 50 %, t90-switching speeds of about 0.45 s and a cycling stability of approximately 200 cycles for a 20 % performance retention, independent of the solvent being used. Conversely, non-nanostructured P3HT films spray-coated from THF or CHCl3 reveal a strong solvent dependent variability in their electrochromic behavior presenting low optical contrast, high switching speeds and fast degradation rates in the case of CHCl3. The solvent independent electrochromic characteristics of P3HT nanoparticle films is related to a consistent availability of accessible electroactive sites provided by a homogeneous porous P3HT network structure formed on the underlying substrate, as probed by SEM and profilometric studies. Our findings reveal that the use of nanoparticles of P3HT and its environmentally benign liquid phase processing, a concept which is extendable to other electrochromic polymers, opens a sustainable pathway toward the large-area fabrication of electrochromic device structures with favorable and consistent performance parameters.

Appearance of mollusk shells related to reflection by absorbing periodically stratified media.

The theory of the optical properties of an absorbing periodically stratified medium is applied to the spectral and angular dependence of the reflectivity of mollusk shells, which are almost-periodic structures of aragonite plates alternating with thinner organic layers. The reflectivity of s and p polarizations show strong variation as the angle of incidence passes through the stop bands of the corresponding ideal non-absorbing periodic structure. For both polarizations of incident light, and at most angles of incidence, the blue and green wavelengths are reflected more than the red-hence the blue-green appearance of mollusk shells.

Capturing the transition from diffuse to localised failure in constitutive modelling of partially saturated soils

Localised failures in the form of shear band induce localised deformation and saturation within partially saturated soils. Inelastic responses mainly take place inside the shear band, while the zone outside it usually undergoes unloading processes with much smaller changes in deformation and saturation, as observed in several triaxial tests. The interaction between responses inside and outside shear bands governs the macro behaviour under effects of the hydromechanical coupling. This mechanism, along with properties of shear band (inclination, thickness) and the specimen size, are usually missing in existing classical models based on homogenous assumption. They are incorporated into our approach to correctly capture the post-localisation behaviour of partially saturated soils. In our proposed approach, enrichment terms for kinematics are used in the thermodynamics-based formulation to account for strong variations of hydromechanical responses (stress-strain, suction-saturation) outside and inside the shear band. The proposed formulation results in a size-dependent constitutive structure capable of describing the transition of behaviour from homogeneous to localised stages. The promising features of the proposed formulation are illustrated using data from drained triaxial tests.

Evolution of discrete symmetries.

Symmetries are known to dictate important physical properties and can be used as a design principle in particular in wave physics, including wave structures and the resulting propagation dynamics. Local symmetries, in the sense of a symmetry that holds only in a finite domain of space, can be either the result of a self-organization process or a structural ingredient into a synthetically prepared physical system. Applying local symmetry operations to extend a given finite chain we show that the resulting one-dimensional lattice consists of a transient followed by a subsequent periodic behavior. Due to the fact that, by construction, the implanted local symmetries strongly overlap the resulting lattice possesses a dense skeleton of such symmetries. We proof this behavior on the basis of a class of local symmetry operations allowing us to conclude upon the "asymptotic" properties such as the final period, decomposition of the unit cell and the length and appearance of the transient. As an example case, we explore the corresponding tight-binding Hamiltonians. Their energy eigenvalue spectra and eigenstates are analyzed in some detail, showing in particular the strong variability of the localization properties of the eigenstates due to the presence of a plethora of local symmetries.

Suburban Blues: Urbanicity, healthcare service mix and spatial patterns of admissions for depression

Abstract Objectives Medical practice variation is a key target for policy makers aiming to improve the efficiency of healthcare delivery. Studies point to strong regional variation in healthcare utilization in Austria which seems to be a by-product of institutional rules and healthcare service mix rather than variance in epidemiology. Methods We use a set of routine healthcare data on hospital admissions for depressive episodes (ICD-10 F320-F329) of adult Austrian patients from 2009 to 2014 on the municipality level to explore spatial patterns of supply-induced demand by nearby hospitals (“Roemer's law”) in hospital admission rates. The dataset covers 99,844 hospital episodes of 69,555 patients in 2,114 municipalities. We estimate a random effects spatial autoregressive model to regress log hospital admission rates on hospital supply and urbanicity as proxies for the municipalities’ healthcare service mix alongside a set of relevant socio-economic/-demographic characteristics. Preliminary results Hospital admission rates per 1,000 inhabitants in the population for depressive episodes vary strongly between municipalities (min=0, max=37.7, mean=1.9, SD = 1.8). We find higher admission rates in the population of suburban municipalities (0.10, 95%-CI: 0.58 - 0.13) and municipalities with hospitals (0.07, 95%-CI: 0.01 - 0.1), regardless of hospital type and size. The spatial structure suggests positive spill-over effects on the hospital admission rates between neighbouring municipalities. Conclusions Our results suggest that high admission rates are a seemingly suburban phenomenon and that healthcare service mix is a driving factor for admission rates. Though it is not clear whether the regional variation in medical practice reflects under- or oversupply of hospital care, promoting timely access to primary care and early-stage treatments may reduce the burden of avoidable hospitalizations for patients and public budgets, and close a gap of unmet need for care of vulnerable populations. Key messages • Hospital admission rates for depression of adults per 1,000 inhabitants in the population for depressive episodes vary strongly between municipalities. • Hospital supply and urbanicity are major driving factors of the spatial patterns in regional varation of hospital admissions.

A Gridded Inventory of Annual 2012-2018 U.S. Anthropogenic Methane Emissions.

Nationally reported greenhouse gas inventories are a core component of the Paris Agreement's transparency framework. Comparisons with emission estimates derived from atmospheric observations help identify improvements to reduce uncertainties and increase the confidence in reported values. To facilitate comparisons over the contiguous United States, we present a 0.1° × 0.1° gridded inventory of annual 2012-2018 anthropogenic methane emissions, allocated to 26 individual source categories, with scale-dependent error estimates. Our inventory is consistent with the U.S. Environmental Protection Agency (EPA) Inventory of U.S. Greenhouse Gas Emissions and Sinks (GHGI), submitted to the United Nations in 2020. Total emissions and patterns (spatial/temporal) reflect the activity and emission factor data underlying the GHGI, including many updates relative to a previous gridded version of the GHGI that has been extensively compared with observations. These underlying data are not generally available in global gridded inventories, and comparison to EDGAR version 6 shows large spatial differences, particularly for the oil and gas sectors. We also find strong regional variability across all sources in annual 2012-2018 spatial trends, highlighting the importance of understanding regional- and facility-level activities. Our inventory represents the first time series of gridded GHGI methane emissions and enables robust comparisons of emissions and their trends with atmospheric observations.

Sleep in a 1-year diary from the mid-18th century.

A 1-year systematic diary was kept by an anonymous diarist in Hamburg in the year 1755-1756. Sleep, activities, food intake, urine volume, and meteorological data were documented daily. The systematic recording of sleep and naps, with an accuracy of a quarter of an hour allowed analysis of the placement, duration, and consistency of sleep. The mean (range) night sleep duration was 6 (3-9) h. The distribution of sleep interruptions showed two peaks, short (≤30 min) and long (≥45 min) interruptions. The latter indicted nights with segmented sleep. Time in bed was subject to strong seasonal variations. Bedtime and rise time were earlier in summer than in winter and sleep latency was shorter in summer than in winter. However, sleep duration displayed a large spread in all seasons and did not differ substantially between summer and winter. Seasonal variations of sleep timing were related to the varying daylight hours during the year. Finally, the results of this individual case may prompt a more detailed investigation of the variability of sleep behaviour in the pre-industrial period.