Night Research Articles

Outcomes of Percutaneous Image-Guided and Laparoscopic Cholecystostomies in High-Risk Patients With Acute Calculus Cholecystitis: A Five-Year District General Hospital Experience.

Introduction Acute cholecystitis (AC), inflammation of the gall bladder, is one of the most common emergency surgical presentations. In the UK, approximately 15% of the population is estimated to have gallstones, and approximately 20% of them can develop AC. Laparoscopic cholecystectomy (LC) is considered the definitive management of AC. However, cholecystectomy carries a very high risk of morbidity and mortality in high-risk frail patients with multiple comorbidities who are deemed unfit for surgery. Percutaneous cholecystostomy (PC), both image-guided and laparoscopic, is generally acknowledged as an interim treatment measure before definitive management, which is the LC. Materials and methods This is a retrospective study from the Royal Albert Edward Infirmary, a district general hospital (DGH) based in Wigan, UK. The medical records of all the patients whowere admitted to the surgical department and underwent PC between January 2017 and December 2022 were analyzed. Patients with previous hepato-pancreato-biliary (HPB) malignancy, who underwent open cholecystostomy, or those withabdominal ascites were excluded from the study. Information was collected regarding the age, gender, American Society of Anaesthesiologists(ASA) grades, success rates of both procedures as temporary or definitive management, duration of hospital stay, 30-day and 1-year mortality after the procedure, timing of the procedure,and long-term complications after the procedure, particularly those related to cholecystostomy tube dislodgment or blockage. Results Twenty-seven patients who underwent PCwere divided into two groups: group A, consisting of 10 patients who underwent laparoscopic cholecystostomies, and group B, consisting of 17 patients who had ultrasound (US)-guided cholecystostomies.The mean age of the patients in group A was 66.7 as compared to 75.1 in group B.Most of the patients were in ASAgroups III (14) and IV (10). About 74% of patients had procedures done during the day and 26% had PC at night time. The mean hospital stay was 13.5 days. About 55% of patients had planned elective LC as a definitive management. Following the treatment, two patients died within 30 days, and eight patients passed away within a year. About 40% of the patients had complications related to the tube dislodgment and blockage. Conclusion This study concludesthat PC, using both laparoscopic and US-guided techniques, can serve as an interim as well as a definitive measure,particularly in patients who are at high risk for anesthesia and the procedure itself and have multiple comorbidities.

Interactions between poor sleep and negative social cognition pose risk for lower maternal sensitivity.

The extent to which mother and infant sleep predict maternal sensitivity as (a) main effects and (b) moderate the association between social cognition about infant crying (i.e., cry processing) and maternal sensitivity was examined in a sample of 299 mother-infant dyads (43% of mothers non-White; 50.5% of infants female). Infant- and mother-oriented cry processing were assessed prenatally using a video recall procedure and mothers self-reported demographics and characteristics reflecting emotional risk. When infants were 2 months old, mothers reported their depressive symptoms and mother and infant sleep. Maternal sensitivity and infant negative mood were observed during free play and the still face. There were no main effects of mother or infant sleep on maternal sensitivity over and above covariates. However, infant total sleep duration across night and day and mother sleep disturbance moderated the effect of mother-oriented cry processing on sensitivity. Specifically, mother-oriented cry processing was associated with lower maternal sensitivity only among mothers whose infants had lower sleep duration and who reported more sleep disturbances. Moderating effects were not apparent for infant night wakings or time awake or mothers' total sleep problems. Constrained opportunities for sleep or respite across the entire day and the totality of mothers' nighttime sleep disturbances, not just those specific to infants' night wakings, undermine maternal sensitivity by exacerbating mothers' preexisting tendency to have self-focused and negative reactions to infant distress. The efficacy of interventions designed to facilitate maternal sensitivity and infant adjustment may be enhanced by adding targeted foci on maternal and infant sleep. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Natural source electromagnetic survey for geothermal application in industrial area with strong electromagnetic noise

The magnetotelluric (MT) method is a widely used geophysical technique for deep structure exploration. However, rapid industrial development has resulted in significant anthropogenic interference for practical applications of this method in recent years. To carry out MT survey in regions with strong electromagnetic (EM) noise, we develop a strategy, in which part of MT sites are set for night time period and a newly proposed automatic clustering method based on MT signal patterns is applied to process measured data from Yingde area in Guangdong. The MT sites are employed in night time to avoid human activity and measure the quiet time MT signal to make sure that we can capture portion of MT signal. Based on cosine similarity, we can use clustering algorithms to separate the signals from the noise. The application of this strategy for geothermal exploration in Yingde area in Guangdong, indicates the validity of our proposed strategy for real geothermal detection.

Night-time and strategies for regeneration in two medium-sized town centres

ABSTRACT This paper examines the regeneration proposals for two town centres in medium-sized towns in the north of England through the lens of urban design and nocturnal activities. Drawing from the field of night studies, it questions whether the hours of darkness have been included in the proposals and compares the extent to which findings and practical guidance from this emergent cross-disciplinary area of interest have been interpreted and incorporated. The paper argues that towns would benefit from addressing the specific characters and qualities of night time activities, including nightlife, in their policies and masterplans for revitalizing town centres.

Analysis of satellite-to-ground quantum key distribution with adaptive optics

Future quantum communication infrastructures will rely on both terrestrial and space-based links integrating high-performance optical systems engineered for this purpose. In space-based downlinks in particular, the loss budget and the variations in the signal propagation due to atmospheric turbulence effects impose a careful optimization of the coupling of light in single-mode fibers required for interfacing with the receiving stations and the ground networks. In this work, we perform a comprehensive study of the role of adaptive optics (AO) in this optimization, focusing on realistic baseline configurations of prepare-and-measure quantum key distribution, with both discrete and continuous-variable encoding, and including finite-size effects. Our analysis uses existing experimental turbulence datasets at both day and night time to model the coupled signal statistics following a wavefront distortion correction with AO, and allows us to estimate the secret key rate for a range of critical parameters, such as turbulence strength, satellite altitude and ground telescope diameter. The results we derive illustrate the interest of adopting advanced AO techniques in several practical configurations.

Checklist of hawkmoths (Lepidoptera: Bombycoidea: Sphingidae) in the Central Highlands of Vietnam

Study on hawkmoths (Sphingidae family) in the Central Highlands of Vietnam (Kon Tum, Gia Lai, Dak Lak, Dak Nong, and Lam Dong provinces) was carried out during the years 2016–2022. Light traps and butterfly nets were used to collect specimens of the Sphingidae family in the night and day times. An update checklist of Sphingidae was based on collected specimens in the studied area and combine the review data. Totally, 113 Sphingidae species from the Central Highlands of Vietnam are recorded. Among them, 78 species are recorded from collected specimens and 35 species without collected specimens are compiled from the literatures. Addition, 14 species are herein added to the known list, including one very rare species, Eurypteryx geoffreyi Cadiou & Kitching, 1990, and two endemic species, Griseosphinx marchandi Cadiou, 1996 and Callambulyx schintlmeisteri Brechlin, 1997.

Solar air dehumidification systems

The solar air dehumidification system permits dehydration of air inside buildings using thermal energy. With thermal energy storage it is possible to organize the continuous process of air dehumidification even in the night time. Recently we have developed low cost solar concentrators that can be used for air dehumidification. The concentrators of this type contain a large number of flat triangle mirrors. The support frame for these mirrors has a shape of a parabolic dish. The experiments with two prototypes of flat mirror solar concentrators show that a stagnation temperature of more than 300ºC can be obtained. This temperature is sufficient to regenerate almost all desiccants that are used for air dehumidification. We estimate the cost of flat mirror concentrators in mass production as 20-30 USD per square meter. This cost permits creation of dehumidification systems for residential and district applications.

Mini-EUSO on Board the International Space Station: Mission Status and Results

The telescope Mini-EUSO has been observing, since 2019, the Earth in the ultraviolet band (290–430 nm) through a nadir-facing UV-transparent window in the Russian Zvezda module of the International Space Station. The instrument has a square field of view of 44°, a spatial resolution on the Earth surface of 6.3 km and a temporal sampling rate of 2.5 microseconds. The optics is composed of two 25 cm diameter Fresnel lenses and a focal surface consisting of 36 multi-anode photomultiplier tubes, 64 pixels each, for a total of 2304 channels. In addition to the main camera, Mini-EUSO also contains two cameras in the near infrared and visible ranges, a series of silicon photomultiplier sensors and UV sensors to manage night-day transitions. Its triggering and on-board processing allow the telescope to detect UV emissions of cosmic, atmospheric and terrestrial origin on different time scales, from a few microseconds up to tens of milliseconds. This makes it possible to investigate a wide variety of events: the study of atmospheric phenomena (lightning, transient luminous events (TLEs) such as ELVES and sprites), meteors and meteoroids; the search for nuclearites and strange quark matter; and the observation of artificial satellites and space debris. Mini-EUSO is also potentially capable of observing extensive air showers generated by ultra-high-energy cosmic rays with an energy above 1021 eV and can detect artificial flashing events and showers generated with lasers from the ground. The instrument was integrated and qualified in 2019 in Rome, with additional tests in Moscow and final, pre-launch tests in Baikonur. Operations involve periodic installation in the Zvezda module of the station with observations during the crew night time, with periodic downlink of data samples, and the full dataset being sent to the ground via pouches containing the data disks. In this work, the mission status and the main scientific results obtained so far are presented, in light of future observations with similar instruments.

Ventricular septal defect complicating anterior acute myocardial infarction : A Case of transcatheter closure

IntroductionPost-infarction ventricular septal defect (PIVSD) is one of the most serious mechanical complications of acute myocardial infarction (AMI). Over the last decade, percutaneous closure is increasingly undertaken, with results similar to cardiac surgery. We present a case of ST-elevated anterior AMI, complicated by apical PIVSD successfully treated with transcatheter closure. Case ReportAn 83-year-old man was hospitalized for chest pain occurred 18 hours before, during the night time. He was an active smoker. Clinical examination revealed normal heart sounds and pulmonary bibasilar crackles. ST-segment elevation with deep T waves inversion in anterior leads were detected on the electrocardiogram. A mildly-reduced ejection fraction (40%) was found by transthoracic echocardiogram. The patient underwent emergency coronary angiography, which revealed a subocclusive stenosis of the mid left anterior descending artery with a TIMI 2 flow, treated by balloon angioplasty and drug-eluting stent. Four days after revascularization, the patient developed an acute deterioration with signs of decompensated heart failure and a new holosystolic murmur with large irradiation. Inotropic agents’ administration was required to maintain a precarious hemodynamic condition. A bedside Echo revealed an apical VSD, measuring 15 × 10 mm, with left-to-right shunting, and pulmonary hypertension. The patient was scheduled for transcatheter PIVSD closure. The procedure was performed under fluoroscopic guide. Two vascular access sites were placed, femoral arterial and right internal jugular vein. Through the right internal jugular vein, a 24-mm Amplatzer atrial septal occluder on a 9 French Amplatzer TREVISIO™ intravascular delivery system was advanced via right ventricle into the PIVSD. Contrast fluoroscopy was used to assess apposition and the degree of shunt reduction before release. Echocardiographic evaluation performed 48 hours later confirmed a correct apposition of the device with insignificant residual shunt. At 6 months follow-up, he was asymptomatic, with unchanged prosthetic findings. ConclusionPercutaneous closure has been emerged as a valid cost-effective alternative to surgery and should be advised. However, debate remains on the optimal preprocedural optimization, timing of repair and modality of treatment.

The influence of the hydrometeorological factors on the CO2 fluxes from the oligotrophic bog surface.

The influence of the hydrometeorological factors on the CO2 fluxes from the oligotrophic bog surface.

Bi-Temporal Analysis of Vegetation Index on Land Surface Temperature in Kottayam, Kerala

The impact of NDVI (Normalized Difference Vegetation Index) on the LST (Land Surface Temperature) as well as on the genesis of surface heat islands in urban areas during two different time periods was assessed in Kottayam district, Kerala, India. Landsat TM, Landsat OLI and TIRS imagery from the years 1988 and 2020 were employed to scrutinize the relationship between NDVI and LST. The area covered under different NDVI classes were quantified. The finding indicated that NDVI of the research region decreased from 0.77 in 1988 to 0.59 in 2020, resulting in an increase in LSTmax from 34.46 °C in 1988 to 40.63 °C in 2020. Decrease in NDVI resulted in an increase in the high UHI class from 20.83 km2 in 1988 to 660.59 km2 and from 7.26 km2 to 181.35km2 in the very high UHI class. An inverse relationship was observed between NDVI and LST, with Pearson coefficients of 0.5737 and 0.5199 for 1988 and 2020, respectively, which indicates that NDVI could serve as a crucial metric for evaluating LST and UHI effects. Future research will explore the effect of seasonal variability in LULCC on LST, day and night time UHI and their impacts on human health and energy consumption.

Hybrid MGWO- CSO optimized high gain Relift Luo converter for PV based grid tied PMBLDC drive system

Permanent Magnet Brushless Direct Current (PMBLDC) motor has become one of the most important motors in high performance drive systems, for industrial uses especially for electric vehicle (EV) applications to minimize their torque and current ripples. This work proposes a PV based high gain DC-DC converter for uninterruptible constant power supply to the PMBLDC drive application. PMBLDC drive with Hall Effect sensorsis used to make the variable speed operation due to its controllability. In this work, a Relift Luo converter is utilized because of its negligible ripple in output DC voltage, high voltage gain and reduced switching losses. To regulate this converter, PI controller is implemented and to tune the parameters of the controller, Hybrid Crow Search -Modified Grey Wolf Optimization (MGWO-CSO) techniqueis implemented. The surplus energy from PV is transferred to grid through Single phase Voltage Source Inverter (1 φVSI) after generatingadequate power to PMBLDC motor. When there is no power in Photovoltaic (PV)cell during night time, stored energy in grid gives supply to the PMBLDC motor. The motor is effectively controlled by the PI controller along with the hysteresis controller. Furthermore, the developed work is executed in MATLAB/Simulink to foreshow its effectiveness. As a consequence, the proposed work accomplished low THD value of 1.34, high efficiency of 98.2% with reduced switching lossescompared to the conventional techniques.

Geospatial and socioeconomic prediction of value-driven clean cooking uptake

Understanding the community-specific values and needs of consumers is essential for effective targeting and planning of energy services such as clean cooking. Many clean cooking programmes do not however consider these values and needs in targeting, as they can be difficult and time-consuming to ascertain. This work therefore explores whether community needs and values related to cooking can be predicted, using a novel approach that understands the relationship between socioeconomic, demographic, and geospatial data. Specifically, this study investigates (i) which values are most closely linked to cookstoves in rural Uganda; and (ii) whether it is possible to predict cookstove prioritisation and related values using openly-available data. Using machine-learning approaches, user-perceived value data from 199 rural low-income households in Uganda are mapped against socioeconomic, demographic, and geospatial data to identify correlations and intersections. The values most closely related to cookstoves were found to be food security, time benefit, accessibility to services, fixed costs, and being healthy. The most important parameters in predicting who would hold these values were found to be: the number of people living in a house; age; quintile 2 of the wealth index; annual accumulated precipitation; forest density; night time luminance; and distance to water source, nearest forest within ten kilometers, and nearest road. This study takes a first step towards enabling energy service providers to target areas with a greater likelihood of uptake based on open-source datasets. While cooking in Uganda is analysed herein, the proposed method can be applied for different geographies and energy services.

Effect of Smartphone Usage during Night Time on Sleep Patterns of Young Adults: A Cross-sectional Observational Study

Introduction: Excessive smartphone usage among adolescents and young adults has been consistently linked to poor sleep. Moreover, smartphone overuse has been associated with daytime tiredness, longer sleeps latency, and reduced sleep duration. The significance of addressing poor sleep among adolescents and young adults is underscored by recent research linking it to adverse physical and psychological health outcomes, such as mood disturbances, impaired cognitive function, and increased risk incidence of hypertension and diabetes. Aim: To evaluate the effects of smartphone usage on sleep quality among individuals using Pittsburgh Sleep Quality Index (PSQI) and hypnogram data. Materials and Methods: In this cross-sectional observational study, sleep patterns were assessed using the PSQI questionnaire and Prime Nap sleep tracker app (version 1.1.4). The study was conducted by Deccan College of Medical Sciences, Hyderabad, Telangana, India. The data was collected in the form of a hypnogram and the study was conducted in the participants’ homes (under domicile conditions) in the city of Hyderabad, Telangana, India from March 2020 to April 2020. A total of 60 participants (both male and female) in the age group of 15-25 years were recruited and divided into two groups: one comprising 30 individuals with regular prolonged exposure to smartphone screens at night, and the other consisting of 30 individuals who experienced minimal or no smartphone exposure once they prepared to sleep. Descriptive statistics were applied to the collected data using Microsoft Excel and IBM Statistical Package for Social Sciences (SPSS) for Windows version 25.0. Results: Adding up the average scores of the seven factors gives a global PSQI score from 0 to 21, with 0-4 indicating good sleep and 5-21 indicating poor sleep. Among those who used smartphones regularly at night time, 20 participants (66.67%) had PSQI score >5 and poor sleep quality, 24 participants (80%) had prolonged sleep latency, 18 participants (60%) had poor sleep duration, 27 participants (90%) had sleep disturbances, and 22 participants (73.33%) had increased daytime dysfunction. Hypnogram abnormalities were seen in >15 participants (50%) of subjects. Conclusion: The prevalence of smartphone addiction is widely acknowledged in the medical literature, highlighting the need for its assessment, especially among adolescents and young adults. The study reveals that poor sleeping habits among participants were attributable either to a lack of awareness or neglect. By recognising the importance of adequate sleep, improvement in the quality of daily activities can be made by reducing daily screen time, consequently alleviating both physical and mental stress. Furthermore, the findings have implications for individuals whose work involves prolonged exposure to computer screens, especially during night time.

Monitoring of Noise Pollution Level during Working and Non-Working Day at Transport Stations, Udaipur, India

Noise is a serious pollutant. In the present study, Railway Station and Bus Stop are selected in Udaipur city of India. The selected site offers a wide difference in human activities. In the framework of the baseline noise assessment, screening of all the selected sites was through an appropriate sound meter application. The data were collected on one working and one non-working day. The assessment of a single day was divided into five phases, for half an hour. It was seen that the level of noise was higher at the Bus station than that of Railroad station. The value of disturbance index was likewise noticed higher at the Bus station than Railroad station. At the Bus station frequency of noise was recorded high at early afternoon as well as additionally at the night time and is least at morning. While at the Railroad Station, level of noise was most extreme at morning and is least during night. Hence the current study shows how transport station causes the clamor contamination. In the current analysis, noise levels at all sites sampled at various times of the day were typically found to be in a wide range, with bus station showing more noise pollution than railway station and that is also in the noon and night time and is least at morning time. This happens as a result of a number of factors, including congested and overcrowded roads, poorly managed traffic, and road development operations

Ishrana radnika koji rade u noćnoj smeni - razlog ili izgovor za nepravilnu ishranu

The availability of artificial light and light-emitting devices has changed human life in relation to time, enabling 24-hour health care, trade, and production, as well as the expansion of social life around the clock. In Europe, about 21% of the labor force consists of shift workers. 10% of the employed population work evening shifts or the night shift, and 7% of employees in Europe regularly work the night shift. According to the Bureau of Labor Statistics, more than 15 million Americans work the night shift. Shift work, especially night-time work, seriously affects dietary habits. It is known that night-time work produces a conflict between the socially determined rhythm of eating and the circadian biological rhythms related to the feeling of hunger, satiety, as well as the metabolism itself. Night meals cause disorders of intestinal motility, affect digestion, absorption, but also the utilization of nutrients and possible medical therapy (if the individual has one). From the point of view of chronobiology, humans belong to diurnal species, which to a certain extent explains why night shift workers have a decreased appetite at night, when the human body is programmed for rest and fasting, as well as for endogenous mobilization of glucose. From the psychosocial aspect, shift workers usually experience a discrepancy between their daily routines (including the meal schedule) and those they have with family and friends, which further leads to even more severe disorders of dietary habits. However, it is difficult to give dietary recommendations regarding nutrition. Firstly, there are no clear views on whether night shift workers should eat during the night hours or not. Secondly, even if night eating is encouraged, definitive evidence is lacking on which types of food should be consumed and which should be avoided. Thirdly, the most nutritious foods may not be available at that time of night. Finally, eating at night certainly has an impact on the metabolism. With all the above in mind, we have tried to provide some useful guidelines regarding these issues.

Design of HVAC System using the Phenomena of Diurnal Temperature fluctuation

The total energy usage of the domestic sector accounts for 35.3% of total global energy consumption of this percentage, 50% is used for room and domestic HVAC systems. We worked for designing a standard module to achieve the maximum temperature difference. In this paper Diurnal Temperature Variation phenomena has been studied. The standard Simulation of the HVAC system using Diurnal Temperature Variation has been performed. The current work is a scale down model of Ground Source Heat Pump which is totally renewable in nature. This scale down model works on Diurnal temperature variation. Diurnal temperature fluctuation is the temperature difference obtained during the daytime and night time with higher and lower soil temperature. Same phenomenon is used to obtain a cooling effect and heating effect as we go deeper inside the Earth. The current work is complete replica of Ground source heat pump where the application of this phenomenon is used. Air as a flowing media is used for heat transfer between soil. The air is meant to be flown through the capillary tubes and at certain depth we get a cooling or heating effect according to atmospheric conditions. Along with that we do have to care about the human leisure requirements, for the very purpose we are also passing some amount of fresh air along with reusing the cool air inside the room by flowing it through the walls of room to provide insulation against the infiltrating heat and other elements that add temperature inside the room. It has been identified the 10.40% reduction in atmospheric air and hence it can be concluded that the geothermal HVAC system can be a sustainable and energy efficient alternative to traditional HVAC system. Also identified that the geothermal HVAC systems offer a promising solution for reducing greenhouse gas emissions and increasing energy efficiency in the building sector.

Seston biomass in plankton assemblages in the Southwestern Atlantic Ocean: spatial, vertical, and temporal variations.

Bioseston is a heterogeneous assemblage of bacterioplankton, phytoplankton, zooplankton, and planktonic debris. A detailed knowledge of biosestons is essential for understanding the dynamics of trophic flows in marine ecosystems. The distributional features of seston biomass in plankton (micro- and mesoplankton) in the Southwest Atlantic Ocean (Rio de Janeiro State, Brazil) were analyzed using stratified samples gathered to a depth of 2,400 m during night time. The horizontal pattern of biomass distribution was analyzed vis-a-vis station depth during both wet and dry periods, with higher values recorded in the continental shelf than in the slope, confirming the terrestrial contribution of nutrient sources to the marine environment. This horizontal variation reinforces the occurrence of seasonal vortices in Cabo Frio and Cabo de São Tomé on the central coast of Brazil. Environmental variables reflect the hydrological signatures of the water masses along the Brazilian coast. The largest seston biomass was related to high temperatures, salinities, and low inorganic nutrient concentrations in tropical and South Atlantic central waters. The observed distribution patterns suggest that seston biomass in plankton in the region may be structured based on partitioned horizontal and vertical habitats and food resources.

Traditional Siddha Approach in Treating Frozen Shoulder (Kumbavatham) by Use of Varmam and Thokkanam Therapy- a Case Study

Adhesive Capsulitis or Frozen shoulder also termed as Kumbavatham in Siddha system of medicine, causes swelling and stiffness in particular shoulder capsule restricting its mobility and ROM. The pain intensity is seen to increase in night times with gradual onset of shoulder stiffness and restriction in movement of the shoulder. Conservatively, it can be treated by analgesics, oral steroids, and intra-articular corticosteroid injections. Sometimes, the symptoms persists despite taking conservative measures, initiating patients to opt for alternative therapies for reducing pain and provide flexibility to the joint. A 34-year male from Bangalore presented with severe pain and restricted movements like abduction, adduction, external rotation and flexion of right shoulder both in active and passive movements for last 6 months. The patient was in distressed condition and even small daily tasks were difficult for him. MRI report confirmed of adhesive capsulitis (kumbavatham), one of the vatha diseases mentioned in Siddha system of medicine. A one-month Siddha vaidyam theraupatic approach incorporating Varmam therapy and thokkanam was administered to him. After 25 days, vast improvement in swelling and stiffness with all movements free in Right shoulder with no pain on moving the right arm. The holistic approach of Siddha medicine has provided the reduction in pain measured on VAS and improved restricted movements which was measured using goniometer and SPADI index. The Siddha system of Medicine is a simple and traditional approach for the treatment of such painful conditions. Conservative management of Adhesive capsulitis through Siddha practices provided significant relief by reducing pain and providing better flexibility in shoulder joints without aid of any analgesics. The paper also gives the details of the method employed and lifestyle modification techniques used to treat the individual.

Navigational Competency is Mediated by Foraging Experience and Light Conditions in the Nocturnal Bull Ant Myrmecia midas

The nocturnal bull ants of the genus Myrmecia, Myrmecia midas travel in both bright and dim settings on the ground and also vertically up on trees navigating towards targets. It is known that foragers retain multiple panoramic memories of terrestrial landmarks as well as celestial cues along their foraging route. It is likely that they can compare these stored views with their current visual input to return to their nest. Here we examined whether nocturnal M. midas foragers’ navigational efficiency and success at view-based navigation suffer at low light levels (night time) compared with daylight levels of brightness. When exposed to panoramic cues in dim conditions, which had dimmer light levels than their peak foraging period, they were less well oriented and less likely to find the nest, with the catchment area smaller at night than during the day. At different displacement distances from the nest, initial navigational behaviours differed. Foragers displayed more scanning near the starting point at shorter distances, while with increasing distance they switched more to loops of systematic searching or heading off in some direction without scans. In the dim conditions, landmark guidance became less effective, perhaps explaining why foragers limit their navigational activities mostly to the twilight hours, when light levels are still adequate, and mostly forage in a tree through the night.