Photographic Data Research Articles

Vertical distribution and acoustic characteristics of deep water micronektonic crustacean in the Bay of Biscay

Vertical distribution of meso- and bathypelagic crustacean are scarcely known. The logistics involved in their studies hinder an adequate assessment of their role in the deep ecosystems. As a result, the literature on zooplankton scattering models is mainly focused on epipelagic organisms, particularly krill species. This study analyses data of the plankton community classified by family from the surface down to 2000 m taken in the Bay of Biscay, but focusses on the meso- and bathypelagic zone. Photographic data was employed to obtain a micronektonic crustacean shape catalogue. The Distorted Wave Born Approximation (DWBA) model was employed to estimate target strength. Pasiphaeidae, Euphausiidae and Acanthephyridae were mainly distributed above 500 m depth, while Benthesicymidae, Sergestidae and Mysidae were concentrated in the lower mesopelagic to upper bathypelagic area. The most abundant species were Euphausiidae and Benthesicymidae with up to 30 and 40 individuals per cubic meter respectively. Standard length ranged from 8 to 85 mm and was significantly related with height but not with depth. The Pasiphaeidae family presented the largest individuals followed by Acanthephyridae and Sergestidae while Euphausiidae, Benthesicymidae, and Mysidae were shorter. An smooth fluid-like response was estimated for shorter organisms, while individuals of 60 mm or higher present TS oscillations from around 60 kHz. Pasiphaeidae present an almost 10 dB higher TS than Sergestidae, Acanthephyridae and Benthesicymidae while Mysidae followed by Euphausiidae produce the lower TS. Simple models of TS values at broadside versus the logarithm of standard length (SL) that can be employed as an approximation of their scattering are provided for four common frequencies (TS = 58.5*log10(SL)-188.7, TS = 57.03*log10(SL)-174.1, TS = 22.48*log10(SL)-157.14, TS = 17.55*log10(SL)-135 and TS = 10.53*log10(SL)-109 at 18, 38, 70, 120 and 200 kHz respectively). Changes in body density and sound speed contrast may increase by 10 or 2 dB the resulting TS respectively but are constant in phase, while orientation can decrease the TS by up to 20 dB at the higher frequencies and alter the spectra to an almost flat trend. This study provides further insight into the vertical distribution and physical characteristics of the micronektonic crustacean families inhabiting the Bay of Biscay down to 2000 m depth. It also estimates their echo from a real-shape catalogue that can be employed to infer knowledge from acoustic recordings, particularly of the lower mesopelagic and the bathypelagic zones.

An expert-based system to predict population survival rate from health data.

Timely detection and understanding of causes for population decline are essential for effective wildlife management and conservation. Assessing trends in population size has been the standard approach, but we propose that monitoring population health could prove more effective. We collated data from 7 bottlenose dolphin (Tursiops truncatus) populations in the southeastern United States to develop a method for estimating survival probability based on a suite of health measures identified by experts as indices for inflammatory, metabolic, pulmonary, and neuroendocrine systems. We used logistic regression to implement the veterinary expert system for outcome prediction (VESOP) within a Bayesian analysis framework. We fitted parameters with records from 5 of the sites that had a robust network of responders to marine mammal strandings and frequent photographic identification surveys that documented definitive survival outcomes. We also conducted capture-mark-recapture (CMR) analyses of photographic identification data to obtain separate estimates of population survival rates for comparison with VESOP survival estimates. The VESOP analyses showed that multiple measures of health, particularly markers of inflammation, were predictive of 1- and 2-year individual survival. The highest mortality risk 1year following health assessment related to low alkaline phosphatase (odds ratio [OR]=10.2 [95% CI: 3.41-26.8]), whereas 2-year mortality was most influenced by elevated globulin (OR=9.60 [95% CI: 3.88-22.4]); both are markers of inflammation. The VESOP model predicted population-level survival rates that correlated with estimated survival rates from CMR analyses for the same populations (1-year Pearson's r=0.99, p=1.52×10-5 ; 2-year r=0.94, p=0.001). Although our proposed approach will not detect acute mortality threats that are largely independent of animal health, such as harmful algal blooms, it can be used to detect chronic health conditions that increase mortality risk. Random sampling of the population is important and advancement in remote sampling methods could facilitate more random selection of subjects, obtainment of larger sample sizes, and extension of the approach to other wildlife species.

A Time Series Analysis of Buddhist Painting Using Digital Image Data

Damage to the painting cultural heritage is recognized through visual observation, photographic data, and conservation diagnosis records, and technology that accurately understands the degree of change over time can prevent damage and be effectively used for conservation treatment. In this study, a time series analysis was conducted to diagnose and compare the conservation status of the past and the present using the digital image of Hanging Painting of Bongjeongsa Temple, Andong (The Vulture Peak Assembly) with different filming times. Color information was analyzed using a digital image analysis program. The shape information and area of crease, exfoliation of painting layer, loss of background material and contamination were calculated using the Relief, Threshold Switching, Color Mapping in HSV space function. Based on the calculated data, the change pattern was confirmed by comparing the damage that occurred in the same area. Quantitative data such as the area of damage and the length of the object were used together to comprehensively compare and analyze the degree of improvement and change in damage that occurred throughout the work to evaluate the change over time.

From ground zero of the pandemic – nurses’ stories via Photovoice

Introduction and aim. With the ongoing COVID-19 pandemic, healthcare workers continue to work selflessly and intensively despite many occupational hazards. Although various studies have been carried out to evaluate the experiences of nurses who play an important role in the fight against the pandemic and the effects thereof, qualitative studies carried out using the photovoice technique are very limited. The aim of this study was to evaluate the experiences of nurses working during the COVID-19 pandemic and show the impact that COVID-19 has had on nurses’ work and daily life using creative photographic data. Material and methods. This qualitative study employed a participatory action research design, and photovoice technique was used. Research data were collected from nurses working in COVID-19 clinics of various hospitals between May and September 2021. Data analysis was performed via a phenomenological interpretation method. Results. Five themes emerged from the data: (1) burnout, (2) anxiety, (3) social isolation, (4) emphasis on professional value, and (5) the value of life. Each theme was presented with representative photographic and written narratives provided by the participants. Conclusion. The findings of this study suggest that nurses experience problems such as burnout, anxiety, and social isolation. All the participants associated these problems with the negative effects of the COVID-19 pandemic on work and daily life. On the other hand, the participants emphasized professional value and the value of life despite all the negativities and risks.

Site fidelity and population parameters of pantropical spotted dolphins in the Eastern Caribbean through photographic identification

The Agoa protected marine area, located in the French West Indies, eastern Caribbean, holds several cetacean species, of which the pantropical spotted dolphinStenella attenuatais the most commonly observed. This species is the focus of whale-watching activities off the leeward coasts of Guadeloupe and Martinique, which has allowed the development of a citizen science program to characterize individuals through the collection of photographic data. Here, we conducted a photo-identification study with a sample of 115,705 photos collected between 2014 and 2019, in which 290 marked individuals (179 in Guadeloupe and 111 in Martinique) were identified. Based on an Agglomerative Hierarchical Classification (AHC) analysis, dolphins from each island were separated into two residency clusters. The Catch–Mark–Release (CMR) POPAN statistical model for open populations estimated the pantropical spotted dolphin populations in Guadeloupe and Martinique at 657 (95% CI: 525–821) and 336 (95% CI: 253–446) individuals for frequent users, respectively, while occasional visitors were estimated at 3,063 (95% CI: 2,133–4,398) and 1,443 (95% CI: 1,024–2,033), respectively. The Martinique population tended to use a reduced coastal area and appeared to be smaller and stable, while the Guadeloupe population showed a slight decline in abundance throughout the study period. These results showed that the leeward coasts of Guadeloupe and Martinique are of particular importance for pantropical spotted dolphin populations, highlighting the need for continued monitoring through both scientific and citizen science programs to fill information gaps on this species in the eastern Caribbean.

First account of apparent alloparental care of a long-finned pilot whale calf (Globicephala melas) by a female killer whale (Orcinus orca)

Interactions between killer whales ( Orcinus orca (Linnaeus, 1758)) and long-finned pilot whales ( Globicephala melas (Traill, 1809)) have been documented on numerous occasions, usually involving predation events and pursuits. Here, the first documented account of a long-finned pilot whale calf seen in echelon position with one killer whale in a group of three killer whales is described, along with one further interaction of the same killer whale group with other long-finned pilot whales. Behavioral, locational, and photographic data were recorded and analyzed for killer whales between 2011 and 2022 and for long-finned pilot whales between 2019 and 2022 off West Iceland. The data were used to obtain background information on the killer whale group involved in the apparent alloparental behavior. The described event also presents the first documented account of epimeletic behavior of a killer whale toward a non-conspecific. The movements of the same killer whale group in conjunction with other killer whales during a subsequent interaction with a group of long-finned pilot whales do not fit any previously observed behavioral patterns described for interactions between these species and may represent an active effort to obtain another long-finned pilot whale calf. Long-finned pilot whale and killer whale interactions might be more complex than previously thought and influenced by multiple drivers.

Abundance of Bering-Chukchi-Beaufort bowhead whales (Balaena mysticetus) in 2004 estimated from photo-identification data

Ice-based surveys near Point Barrow, Alaska, have been used to obtain most estimates of abundance for the Bering-Chukchi-Beaufort (B-C-B) stock of bowhead whales, but global warming has raised concerns that ice-based surveys may not be practical in the future. Aerial photographic surveys provide an alternative method for obtaining abundance estimates and may replace ice-based surveys. Aerial photographic surveys were conducted near Point Barrow during the spring migrations of bowhead whales in 2003 and 2004 and, in 2005, in the northern Bering Sea in spring and near Barrow in fall. The 2003 survey was the most complete photographic survey of the population conducted to date. These surveys provided photo-identification data for use in capture-recapture analyses. A screening procedure was used to define which whales captured in 2003, 2004 and/or 2005 were marked and could be reidentified if photographed on another occasion. An estimate of the number of marked whales was obtained using a closed population model for capture-recapture data. Several models were investigated, including models that accounted for heterogeneity in capture probabilities, but a simple model with no covariates produced the most precise estimate. To account for unmarked whales, the estimate of marked whales was divided by an estimate of the proportion of the bowhead population that was marked based on the 1989–2004 spring photographic surveys near Point Barrow. Abundance of the B-C-B bowhead population in 2004 (excluding calves) was estimated to be 12,631 with CV 0.2442, 95% bootstrap percentile confidence interval (7,900; 19,700) and 5% lower limit 8,400. These results were compared with results that used approximate variance expressions for the estimates of the number of marked whales, the proportion of the population that was marked and population abundance instead of using the bootstrap. The estimates of abundance in 2004 computed for comparison included one based on a modified Petersen estimate of the number of marked whales that omitted the 2005 data as well as the estimate of 12,631 described above. The comparison estimates also included estimates of abundance in 1985 computed from 1984–87 photographic survey data using the same methods. All the abundance estimates computed from photographic data were consistent with expectations based on independent abundance and trend estimates from the ice-based surveys conducted from 1978 to 2001.

Two New species of Impatiens (Balsaminaceae) from Myanmar

Impatiens yinyinkyii M.M.Latt, B.B.Park & Nob.Tanaka and I. horizontalis M.M.Latt, B.B.Park & Nob.Tanaka (Balsaminaceae) are described and illustrated. Those new species were discovered in Htamanthi Wildlife Sanctuary, northwestern Myanmar. Description, photographic data as well as the comparative characters with their similar species are provided. Impatiens yinyinkyii is similar to I. masonii Hook.f., but differs in having three dark purple blotches in center of flower, specifically at base of dorsal and upper petals of united petals. Impatiens horizontalis resembles I. stenantha Hook.f., I. prostrata Hook. f., I. repens Moon, I. procumbens Franch and I. reptans Hook. f. in having larger, glabrous and elliptic to lanceolate leaves, serrate margin with antrorse bristles, deeply bucciniform lower sepal, twisted spur with abruptly capitate tip, linear ovary, spheroid seed and finally uncommon conspicuous stout stem which is horizontally creeping.

Glacier retreat analysis in the context of climate change impact over the Satopanth (SPG) and Bhagirathi-Kharak (BKG) glaciers in the Mana basin of the Central Himalaya, India: A geospatial approach

• Glacier retreat footprints over the Mana Basin. • Spatio-temporal changes in the snout/glacier over the period of 50 years. • Estimation of ice velocity using the SAR technique. • Negative trend in snow cover area and increase of temperature. This study explores the dynamics of the Satopanth (SPG) and Bhagirathi-Kharak (BKG) glaciers of the Mana basin in the Central Himalayan region of India under the scenario of climate change. The spatio-temporal changes in the glacier area, volume, and shift in snout positions during the period from 1968 to 2017 were assessed based on the CORONA photograph and satellite data . The study also intended to identify the common drifts in glacier areas for observing temporal and seasonal (during the winter-spring-summer transition) changes in the glacial landscapes and ably evaluate glacier velocity and ice-marginal lake stage. The ice velocity was found to vary from 0.117 md −1 to 0.165 md −1 for January to October months. It was found to have increased during the winter-spring-summer transition periods used to estimate the ice flow intensity and its phase information regular basis. Besides this, the linear trends of the MOD11A2 land surface temperature product were obtained and temperature variability has been analyzed from 2001 to 2020. The results show significant warming over the basin along with a significant negative trend in snow cover area during different seasons. The derived information is quite useful in analyzing the climate change footprints such as snowline movement, snow volume changes, and glacier mass balance-related studies.

Extralesional cryotherapy combined with intralesional triamcinolone injections after keloid excision

Background Keloid treatment is challenging because of the high likelihood of recurrence and a lack of definitive treatment combinations. The treatment of bulky and recurrent keloids is particularly difficult. We investigated the administration of extralesional cryotherapy (EL) in conjunction with intralesional (IL) triamcinolone (TA) injections as adjuvant therapy after surgical excision for the management of keloids.Methods Among all patients who visited our scar laser center between January 2016 and August 2017, 54 patients who underwent IL keloid excision with EL cryotherapy and IL TA injection as adjuvant therapy were included in this retrospective study. We examined sex, site, the number of cryotherapy sessions and TA injections, symptoms after surgery, and recurrence. The Vancouver Scar Scale (VSS) was used as to quantify treatment outcomes.Results Among 54 cases of IL keloid excision, after an average of 6.26 cryotherapy sessions and IL TA injections as combined adjuvant treatment, the lesion was controlled without recurrence in 49 cases. Relapse occurred in five patients, requiring additional treatment and reoperation. For 49 patients with photographic data, the average VSS score before and after treatment improved from 10.1 to 5.0. In 17 patients in whom symptoms recurred after surgery, all symptoms were controlled and maintained with adjuvant therapy.Conclusions Initial direct surgical excision, followed by a combination of EL cryotherapy and IL TA injections, was shown to be effective in challenging cases of large and recurring keloids.

Youth participation in traditional cultural practices in contemporary Tumu: An exposé on the Ceremonial Costume Art of Fuowie Nasolo, a youth cultural iconic figure in Tumu

Youth participation in traditional cultural practices in contemporary Africa (Ghana) has been on the decline due to the alarming rate at which African youth assimilate foreign cultures. Many African (Ghanaian) youth nowadays mock African (Ghanaian) ethnic cultures in favour of Western cultures. However, previous research suggests youth cultural activism in Tumu, Ghana. This positive development has the tendency to preserve and promote the cultural identity of Tumu. This study, therefore, sought to establish the motivation behind youth participation in traditional cultural practices in contemporary Tumu with a specific focus on the costume art of Fuowie Nasolo, a youth cultural iconic figure in Tumu. Qualitative descriptive analysis of interview transcripts and photographic data gathered from twenty-five (25) heterogenous-purposively sampled informants reveal that youth cultural activism in contemporary Tumu is engendered by the sustained cultural tutelage provided by the elders of Tumu. Additionally, it was emphasised that youth cultural participation in contemporary Tumu is extrinsically motivated by the admirable cultural activism of Fuowie, the unifying leader of Tumu youth cultural group. A cursory study of the cultural manifestations of Fuowie’s ceremonial costume art, reveals the royal, heroic, and wardress culture of the indigenes of Tumu. Since Fuowie’s cultural activism significantly complements the effort of Tumu elders in promoting youth cultural participation, the study calls for sustained collaboration between Fuowie and the elders of Tumu to massively promote youth participation in traditional cultural activities for cultural preservation, cultural restoration, and the construction of authentic cultural identity of the people of Tumu for posterity.

Monitoring of protected fungi species by methods of modern information technologies

Monitoring of protected fungi species by methods of modern information technologies

Alcohol Use During the COVID-19 Pandemic: A Visual Self-Narrative Longitudinal Study About Various Drinking Habits During COVID-19

During the COVID-19 pandemic, people faced life-threatening uncertainties with sociopsychological implications, and increased alcohol usage has been found to be a maladaptive form of coping induced by pandemic-related stress and isolation. Despite this, alcohol has also been found to increase people’s willingness to socialize and reduce stress. We employ visual self-narrative to investigate a research gap into the usage of alcohol, thereby examining the varying roles alcohol has played in people’s lives. Photographs offer deeper understanding through a collection of perishable data into social phenomena, and allow inquiry into sensitive topics with vulnerable populations. Our study, which found alcohol can play a helpful role in coping, further suggests photographic data should be considered in public health research.

New and confirmed species of operculate cup fungi (Ascomycota, Pezizomycotina) in Tunisia

Three taxa of macromycetes, Otidea alutacea, Otidea bufonia and Phylloscypha phyllogena, were first recorded in Tunisia. Occurrences of Humaria hemisphaerica and Peziza vesiculosa were confirmed from the northwestern part of Tunisia more than 100 years after their first records in the northeast and the southwestern parts of the country, respectively. The species reported belong to three families of the Pezizales order (Otideaceae, Pezizaceae and Pyronemataceae). Short descriptions of their distinctive macroscopic and microscopic features, ecology and geographical distribution in Tunisia are given. The locality, the data of collection and field photographs for each species are also presented.

Analysis of Inheritance patterns, gender dimorphism and their correlation in lip and palm prints - A cross-sectional study.

Forensic sciences deal with key areas to be included in judicial makeup that has been approved by both the court and the scientific community, which distinguishes truth from counterfeit. Lip and palmprints are one of a kind and do not change during the lifetime of a person unless any pathologies. To evaluate the heritability, and gender dimorphism of lip and palm prints among parents and their offspring. A total of 280 participants were included in the study. Lip and palm prints were collected from participants using a digital camera. The photographic data obtained is subjected to Adobe Photoshop and analysed for inheritance. Gender dimorphism is evaluated by the predominant lip pattern and palm ridge count in four designated areas. A positive resemblance of 28.4% was found between parents and offspring in lips, and for the right palm, it was 60.2% and 55.12% for the left palm (principal lines) which are statistically insignificant. In all six quadrants, the most predominant lip pattern found in males is type 5, and in females, type 11. The mean palm ridge density was significantly higher among females than males in all designated areas. The digital method of analysing lip and palm print images with Adobe Photoshop 7 software is a convenient method that allows for better visualisation and easier lip and palm print recording and identification. Considerable inheritance patterns and gender dimorphism were observed that aid in personal identification.

A narrative review on the use of camera traps and machine learning in wildlife research

Camera trapping has become an important tool in wildlife research in the past few decades. However, one of its main limiting factors is the processing of data, which is labour-intensive and time-consuming. Consequently, to aid this process, the use of machine learning has increased. A summary is provided on the use of both camera traps and machine learning and the main challenges that come with it by performing a general literature review. Remote cameras can be used in a variety of field applications, including investigating species distribution, disease transmission and vaccination, population estimation, nest predation, animal activity patterns, wildlife crossings, and diet analysis. Camera trapping has many benefits, including being less invasive, allowing for consistent monitoring and simultaneous observation (especially of secretive or aggressive animals even in dangerous or remote areas), providing photo/video evidence, reducing observer bias, and being cost effective. The main issues are that they are subject to their environment, dependent on human placements, can disrupt animal behaviour, need maintenance and repair, have limitations on photographic data, and are sensitive to theft and vandalism. When it comes to machine learning, the main aim is to identify species in camera (trap) images, although emerging technologies can provide individual recognition as well. The downsides in- clude the large amount of annotated data, computer power, and programming and machine learning expertise needed. Nonetheless, camera trapping and machine learning can greatly assist ecologists and conservationists in wildlife research, even more so as technology further develops.

Examining Language Accessibility in the Linguistic Landscape of Tanzania: The Case of Labels on Pre-packaged Foods and Beverages

This study examined the language accessibility on labels of commercially produced pre-packaged foods and beverages in Tanzania, targeting local consumers, and its implication on information access. Being guided by Backhaus (2005) and Spolsky (2004) Sociolinguistic Framework, the study extends the scenery of research in the field of linguistic landscape (LL) that places the presumed reader(s) as key actors in analysing LL. The study analysed 129 photographic data (semiotic resources) from labels of pre-packaged foods and beverages collected randomly from six shopping locations in Dar es Salaam. It also interviewed 25 respondents. Findings revealed that two main languages, English and Kiswahili were observed on the studied pre-packaged food and beverage labels. However, it is English and not Kiswahili (the official and national language) which is mostly represented on labels of commercially produced pre-packaged foods and beverages in Tanzania. The majority of local consumers who are not proficient in the most preferred language on labels were reported to have difficulties in reading and understanding the information written on labels a situation that hinders their access to the information contained on labels.

The Building Stock in the City of Dubai: A Survey Methodology

In 2003, new building regulations were introduced in the city of Dubai. In 2012, the municipality requested a survey of every building that existed prior to that year. This paper documents the method used for this significant undertaking, not performed by any other large city. The survey was conducted using a combination of Global Positioning System (GPS)-enabled photography and field visits. Multiple images were taken of every street, resembling progressive film imagery, with every building recorded multiple times in the image sequence. The location-tagged images were superimposed on a city map and compared to historical satellite maps of the city from Google Earth history timelines. Whenever the photographic data was not enough to adequately classify a building, field visits were conducted. That was necessary for around 10% of the city structures. The fieldwork was conducted by two teams, each comprising two engineers, and took four weeks to complete. The results showed that, in 2003, there were around 37,000 buildings in the city. Of those, almost 89%, were low-rise (1–2 floors) and largely single-unit residential houses. Nearly all buildings were found to be built after the mid-1980s, and in very good structural condition. The system described in this paper may be applied to any other large-scale city building survey.

What’s Black and White and Pink All Over? Lesser Flamingo Nocturnal Behaviour Captured by Remote Cameras

The study of animal behaviour is important for the development of husbandry and management practices for zoo-housed species. Yet, data are typically only collected during daylight hours, aligning with human work schedules rather than animal activity patterns. To remedy this, 24 h data collection is needed. This study investigated the behaviour of a captive flock of lesser flamingos to understand temporal changes in their time-activity patterns. Two remote camera traps were placed around the birds’ outdoor enclosure and one within the indoor house. Counts of birds visible within specific enclosure zones were recorded from photographic data. Behaviour was defined as active or inactive, and modified Spread of Participation Index (SPI) was used to calculate enclosure zone occupancy. Results indicated that lesser flamingos are active overnight, and to a similar amount as in the daytime. Proportions of birds observed as active were significantly higher at later times of the day (i.e., dusk) when compared to the number of active birds in the morning. Enclosure usage was diverse and indoor and outdoor zones could be used by different numbers of birds at different times of the day. Variation in enclosure usage may indicate the changing needs of the flamingos when housed indoors overnight and when they have night-time access to an outdoor enclosure. This research has identified the need for further research into the nocturnal behaviour and space use of lesser flamingos and suggests the need for 24 h research in captive birds, and other zoo-held species, especially when species are locked indoors or face behavioural restriction overnight due to biosecurity measures surrounding zoonoses outbreaks, e.g., Avian Influenza.

Season, age, sex, and location impact the density of tooth rake mark and dorsal fin notch ofIndo‐Pacifichumpback dolphins (Sousa chinensis) in the northern South China Sea

AbstractTooth rake marks are usually used as an indicator of received aggression in odontocetes whose social interactions are difficult to observe directly. Photographic data from five locations of the northern South China Sea were used to analyze seasonal, demographic, and geographic effects on the density of tooth rake marks and dorsal fin notches in Indo‐Pacific humpback dolphins (Sousa chinensis, IPHDs). The analysis revealed that fresh tooth rake marks were most frequent during the dry season. Males exhibited significantly higher rake mark density than females and rake density declined significantly with age. The density of notches was also significantly higher for males than for females, and lower for young dolphins than for mid‐aged and adult ones. Geographically, tooth rake mark and notch density were the highest in Sanniang Bay and Southwestern Hainan. These results provide indirect evidence of variation in social interactions across seasons, across the lifespan of an individual, between sexes, and among different locations. This variation may result from changes in biological parameters, differences in social lives, and habitat characteristics. A model to determine the sex of dolphins was tested, and after further validation, such sex assignment could contribute to understanding IPHDs' social structure.