Combative Behavior Research Articles

Behavior modeling method and its application in combat simulation

Behavior Modeling and Simulation is an important method to analyze macro-and micro-behaviors of groups and individuals. It can predict and analyze the law of crowd activity under a certain density and provide important support for the study of social and economic activities and war and military activities. It has been widely used in emergency response, combat simulation and many other fields. This paper reviews behavioral modeling and simulation, mainly from the current situation of behavioral simulation applications, the main methods of behavioral modeling and the needs of future development direction. Firstly, the application status of behavior simulation is analyzed from both military and social aspects. In the aspect of social behavior simulation, it mainly analyses several aspects, such as safe evacuation, automatic driving, road traffic planning, intelligent robots and so on. In the aspect of military behavior simulation, it mainly analyses individual combat behavior simulation, battlefield element model construction, combat action combination model, multi-agent coupling simulation and so on. Secondly, the method of behavior modeling is deeply analyzed, and the main models of behavior modeling are summarized, including social force model, cellular automata model, agent model, etc. At the same time, the behavior model of individual’s multiple forces in a certain environment and the emergence effect model of group are deeply analyzed. Finally, based on the above two aspects of research and analysis results, this paper aims at the simulation of multi-person cooperative attack and defense, which is a military behavior simulation problem. From the four aspects of dynamic environmental factors, operational rules constraints, enemy threat factors and multi-agent cooperative control, this paper puts forward several problems that need to be further improved in cooperative attack and defense.

Heroin Adulterated with the Novel Synthetic Cannabinoid, 5F-MDMB-PINACA: A Case Series.

IntroductionHeroin can be adulterated with various substances that may or may not have pharmacological effects. Here we report a case series of 8 patients who presented to the emergency department after overdose with intravenous heroin preparation adulterated with the synthetic cannabinoid methyl 2-(1-(5-fluoropentyl)-1H-indazole-3-carboxamido)-3,3-dimethylbutanoate (5F-MDMB-PINACA).Case SeriesExcept for one patient, all of them presented with a typical initial opioid toxidrome consisting of central nervous system and respiratory depression along with pinpoint pupils. Naloxone was given to them, triggering severe agitation and combative behavior along with overlapping features of anticholinergic and sympathomimetic toxidrome. All patients required multiple doses of benzodiazepines. Three were successfully treated with physostigmine.Discussion5F-MDMB-PINACA is a synthetic cannabinoid that was added to heroin in samples obtained from patients reported in this case series. Patients demonstrated significant agitation after receiving naloxone for opioid toxidrome, presumably because of the removal of the depressant effect of opioids, which unmasked the excitatory effects of the synthetic cannabinoids. Three patients required physostigmine along with the benzodiazepines for control of their agitation, urine retention and abnormal vitals, suggesting the possibility of an anticholinergic toxidrome to have developed in these patients.ConclusionHeroin contaminated with 5F-MDMB-PINACA exhibits variable severities of anticholinergic effects, some on presentation and others only after opiate antagonism.

The contribution of the Irish soldier to the British Army during the Peninsula campaign 1808 – 1814

The majority of the historiography concerning the Irish contribution to the British army during their campaign on the Iberian Peninsula (1808 -1814) has focused on the Irish regiments and their service with Wellington in Portugal, Spain and France. While the significance of research into these regiments is undeniable it has unintentionally resulted in an under appreciation of the true extent of the Irish soldier’s contribution. The purpose of this paper is to add to the existing historiography by examining the wider Irish contribution in order to arrive at an empirical based assessment as to the criticality of the Irish soldier to Wellington’s victory during the Peninsula war. The majority of Irish soldiers who served in the Peninsula did so in English and Scottish infantry regiments. Their abilities and crucially their integration into the British army were key success factors for Wellington during the Peninsula campaign. An examination of how this was achieved forms a key part of this paper which finds that the capabilities of the Irish soldier and the British army organisational structure and system mutually supported each other. Furthermore, the Irish officer’s contribution has only been assessed based on individual accounts and narratives in the absence of any in-depth evaluation of their actual numbers. With over 30 per cent of Wellington’s officers being Irish an analysis of their levels of command was undertaken to demonstrate their significance to the overall conduct and operation of the Peninsula army. To fully understand the Irish soldier’s contribution an assessment of their combat effectiveness building on the preceding quantitative findings and utilising modern concepts of combat motivation and behaviours was undertaken. The findings indicate that while the Irish soldier’s contribution was much wider and central to victory in 1814 than is generally appreciated or understood, the British army of the period recognised its importance and, despite popular misperceptions, did not at an institutional level seek to discriminate against the Irish soldier. The paper concludes that Irish soldiers were of critical importance to British victory not only in terms of their numbers but also due to their successful integration into the wider British army outside of Irish regiments, their presence in large numbers at all levels of command and their overall combat effectiveness. Without this contribution it can be argued that British victory would not have been achieved in the Peninsula.

Anaesthesia in a Child with Autistic Spectrum Disorder and Obesity: A Case Report


 
 
 
 Autism is a neurodevelopmental disorder that manifests in the first three years of life. Children may attend hospital for diagnostic and therapeutic procedures at different points of their lives. Due to increased anxiety of patient and family members, uncooperative or combative behaviour, these patients are considered to be difficult cases for anaesthesia. Overweight and obesity in children has become endemic and perioperative complications are more frequent in these patients. A versatile approach should be adopted for management of these patients.
 
 
 

Intraspecific male combat behaviour predicts morphology of cervical vertebrae in ruminant mammals.

Cranial weapons of all shapes and sizes are common throughout the animal kingdom and are frequently accompanied by the evolution of additional traits that enhance the use of those weapons. Bovids (cattle, sheep, goats, antelope) and cervids (deer) within the mammal clade Ruminantia are particularly well known for their distinct and varied cranial appendages in the form of horns and antlers, which are used as weapons in intraspecific combat between males for access to mates. Combat in these species takes many forms, including head-on collisions (ramming); stabbing an opponent's head or body with horn tips (stabbing); rearing and clashing downwards with horns (fencing); or interlocking antlers or horns while vigorously pushing and twisting (wrestling). Some aspects of weapon and skull morphology have been linked to combat behaviours in bovid and cervid species, but the contribution of postcranial structures that support these weapons, such as the neck, has not been explored. To investigate the role of the neck in intraspecific combat, we quantified biomechanically relevant linear variables of the cervical vertebrae (C1-C7) from males and females of 55 ruminant species. We then used phylogenetic generalized least-squares regression to assess differences among species that display primarily ramming, stabbing, fencing and wrestling combat styles. In males, we found that wrestlers have longer vertebral centra and longer neural spines than rammers, stabbers or fencers, while rammers have shorter and wider centra and taller neural spine lever arms. These results suggest a supportive role for the cervical vertebrae in resisting forces generated by male-male combat in ruminant mammals and indicate that evolutionary forces influencing cranial weapons also play a role in shaping the supporting anatomical structures.

Delirium in the PICU

Introduction: Delirium is a well-documented problem in the adult population however, its importance in the paediatric population has evolved recently with the development and validation of reliable paediatric delirium (PD) assessment tools. Definition: The key feature of delirium is an alteration in both cognition and arousal. The American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5)1, defines delirium as a noticeable change in the patient's neurocognitive baseline with an acute disturbance in attention, awareness, and cognition, and is thought to be a direct result of another medical condition rather than due to an established/evolving neurocognitive disorder. Epidemiology: The overall prevalence of delirium in PICU ranges from 4% to 29%, with a recent multi-institutional PD study assessing 994 children for delirium in 25 different PICUs reporting a prevalence of 25%.2 Higher rates have been reported in children < 5 years of age.3 A PD prevalence of 49% was found in a paediatric cardiac ICU population. A prevalence rate of 27% was described in a postoperative paediatric population (delirium incidence of 65% within 5 days after surgery).3 Pathophysiology: Many hypotheses have been proposed. The neuroinflammatory hypothesis suggests that systemic inflammation leads to endothelial activation, enhanced cytokine activity, and infiltration of leukocytes and cytokines into the central nervous system (CNS), producing local ischemia and neuronal apoptosis. The neurotransmitter hypothesis suggests that dysregulation of neurotransmitters like acetylcholine, dopamine, and gamma aminobutyric acid leads to the development of delirium. The oxidative stress hypothesis suggests that hypoxia coupled with increased cerebral metabolism, leads to the production of reactive oxygen species that cause global CNS dysfunction.3 Risk factors: Risk factors are divided into predisposing and precipitating factors many of which are modifiable (Table 1).3 Presentation: PD presents in three major subtypes. Hyperactive delirium is characterized by agitation, restlessness, hypervigilance, and combative behaviour, hypoactive delirium is characterized by lethargy, inattention, and decreased responsiveness and mixed type delirium which exhibits aspects of both hyperactive and hypoactive delirium.1 Hypoactive and mixed type delirium are common presentations in children followed by hyperactive variety. Hypoactive delirium can be easily missed without appropriate screening and diagnostic tools for assessment.3 PD screening tools: Various screening tools have been developed to detect PD with their advantages and limitations (Table 2). Treatment: Management of delirium involves a multidisciplinary stepwise approach (Figure 1)3 including the management of the underlying medical illness, minimizing iatrogenic triggers, and optimizing the PICU environment. Pharmacotherapies are indicated if delirium persists and a child's agitated behaviour is distressful or interferes with medical care. Haloperidol, risperidone, and quetiapine have been used safely in children.5 Outcome and prevention: PD is associated with increased length of mechanical ventilation, increased hospital stay, higher resource utilization, increased healthcare costs, and increased mortality. PD is a hospital acquired complication which can be prevented by using analgosedation approach with the goal to optimize pain and minimize sedation, minimizing iatrogenic factors, early mobilization, and involvement of family members in daily care.3 Conclusion: PD is an important underrecognized issue in the PICU which needs to be prevented, detected early using screening tools, and managed using a multidisciplinary team approach.

Fear in Hebrew

This article examines Hebrew translations of World War II–era psychology handbooks as means of transmission for scientific knowledge and as a mechanism for the cross-cultural spread of behavioral modernity. While drawing a broad, vivid picture of transnational military mobilities postwar, the article centers on the story of one such handbook: John Dollard’s Fear in Battle, a 1943 self-help guide on combat behavior. Produced in the context of efforts to manage the morale of American troops, Fear in Battle then traveled overseas along with volunteers, mercenaries, and special advisors from the former Allied powers, and played a role in decolonization and nation-building in the Middle East. The article reconstructs each phase of the text’s geopolitical and institutional itinerary: the experimental work on aversive conditioning that led to its writing and the larger neobehaviorist agenda it formed a part of; its function within the United States Army and subsequent transit to Palestine; and its translation into two new versions that circulated among Jewish militia members during the 1948 Palestine War. Analyzing in detail changes in language, style and format, the article thus aims to unpack the process by which behavioral science had been vernacularized and its mode of explanation went global.

Spider mite mothers adjust reproduction and sons' alternative reproductive tactics to immigrating alien conspecifics.

Maternal effects on environmentally induced alternative reproductive tactics (ARTs) are poorly understood but likely to be selected for if mothers can reliably predict offspring environments. We assessed maternal effects in two populations (Y and G) of herbivorous arrhenotokous spider mites Tetranychus urticae, where males conditionally express fighting and sneaking tactics in male–male combat and pre-copulatory guarding behaviour. We hypothesized that resident mothers should adjust their reproduction and sons’ ARTs to immigrating alien conspecifics in dependence of alien conspecifics posing a fitness threat or advantage. To induce maternal effects, females were exposed to own or alien socio-environments and mated to own or alien males. Across maternal and sons' reproductive traits, the maternal socio-environment induced stronger effects than the maternal mate, and G-mothers responded more strongly to Y-influence than vice versa. G-socio-environments and Y-mates enhanced maternal egg production in both populations. Maternal exposure to G-socio-environments demoted, yet maternal Y-mates promoted, guarding occurrence and timing by sons. Sneakers guarded earlier than fighters in Y-environments, whereas the opposite happened in G-environments. The endosymbiont Cardinium, present in G, did not exert any classical effect but may have played a role via the shared plant. Our study highlights interpopulation variation in immediate and anticipatory maternal responses to immigrants.

KETAMINE IN THE ICU: TREATMENT OF POLYPHARMACY WITHDRAWAL SYNDROME

SESSION TITLE: Wednesday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM INTRODUCTION: We present a case of severe polypharmacy withdrawal syndrome that was successfully treated with intravenous ketamine. CASE PRESENTATION: A 39-year-old male presented with aspiration pneumonia and hypoxic respiratory failure requiring mechanical ventilation for adult respiratory distress syndrome. He had a history of polysubstance abuse, bipolar disorder and severe anxiety, requiring psychiatric medications. High doses of propofol, midazolam, fentanyl, and dexmedetomidine were needed to control severe agitation while on the ventilator. There was substantial improvement in gas exchange and chest imaging to the extent that extubation was attempted following a successful spontaneous breathing trial. Soon after, the patient developed severe agitation with combative behavior and tachypnea that persisted despite sedative agents. The patient was reintubation followed by repeated attempts to adjust midazolam, propofol, fentanyl, and dexmedetomidine to levels that would control his agitation. A second extubation attempt was unsuccessful, and he required reintubation due to severe agitation, combative behavior as well as inability to control secretions. Intravenous ketamine was started - initial bolus 1 mg/kg followed by rapid titration to 2 mg/kg/hour to achieve coma. Fentanyl, propofol, midazolam, and dexmedetomidine were reduced and eventually discontinued completely. Ketamine was reduced until the patient was alert, calm, and cooperative followed by successful extubation. Ketamine was then tapered off, and the patient was transferred to the medical floors. DISCUSSION: We report the empiric use of ketamine to control severe agitation that was associated with successful extubation. Likely a history of polypharmacy recreational drug use combined with the need for very high dose of sedatives and opiates required for safe ventilatory support resulted in a severe withdrawal syndrome. Thus ketamine was chosen as a single agent to control delirium and combative behavior while discontinuing sedatives. Ketamine, an NMDA (N-Methyl-D-Aspartate) receptor antagonist in the central nervous system and spinal cord, is used as a sedative with dissociative and analgesic properties. This drug has several advantages: quick onset of action in thirty seconds of intravenous administration, short half-life, preservation of respiratory drive, and sympathomimetic effect that reduces risk of hypotension that is common with sedative agents. There are several reports its use in severe alcohol syndrome. Our case illustrates the potential benefit of ketamine to control polypharmacy withdrawal syndrome. CONCLUSIONS: This case shows that ketamine may have utility for control of severe agitation that is associated with withdrawal from high doses of sedatives and opiates required for the critically ill patient on mechanical ventilatory support with history of psychiatric illness and polysubstance drug use. Reference #1: Benken, S. T., & Goncharenko, A. (2016). The Future of Intensive Care Unit Sedation: A Report of Continuous Infusion Ketamine as an Alternative Sedative Agent. Journal of Pharmacy Practice, 30(5), 576-581. Reference #2: Malnoske, M. L, & Quill C (2017). Ketamine to facilitate weaning from mechanical ventilation: A case report. Journal of Anesthesia and Critical Care Case Reports, 3 (1), 11-13. Reference #3: Shah P, McDowell M, Ebisu R, Hanif T, Toerne T. Adjunctive Use of Ketamine for Benzodiazepine-Resistant Severe Alcohol Withdrawal: a Retrospective Evaluation. Journal of Medical Toxicology. 2018 Sep 1;14(3):229-36. DISCLOSURES: No relevant relationships by MORDECHAI GRABIE, source=Web Response No relevant relationships by Becky Lou, source=Web Response No relevant relationships by Paul Mayo, source=Web Response

PROLONGED LYSERGIC ACID DIETHYLMIDE INDUCED SEROTONIN SYNDROME

SESSION TITLE: Wednesday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM INTRODUCTION: Serotonin syndrome (SS) is a life threatening condition which may often be difficult to diagnose. The increasing incidence of SS is attributable to the wide use of selective serotonin reuptake inhibitors, opioids, and recreational drugs like Lysergic Acid Diethlymide (LSD) which act primarily through 5-HT2 serotonin receptors1. Severe cases often require aggressive intervention in the Intensive Care Unit (ICU) to manage hyperthermia, ventilation, seizures, delirium, rhabdomyolysis, and autonomic instability; however, frequently used analgesics in the ICU such as Fentanyl also contribute to increasing serotonergic levels, thereby, prolonging SS2. CASE PRESENTATION: A 28 year old male visiting from Europe with an unknown medical history was brought in to the hospital after sudden onset of diaphoresis, agitation, and confusion at a restaurant. He presented in status epilepticus with combative behavior leading to intubation, sedation, and paralysis. Seizure control required multiple agents. Initial objective data revealed no electrolyte or metabolic abnormalities, and negative toxicology. Imaging of the brain and infectious workup was unremarkable. Within hours, the patient became hyperthermic and hypertensive; pertinent exam findings included clonus and hyperreflexia. Based on these findings, SS versus sympathomimetic toxicity were the highest on our differential diagnosis. Treatment with cyproheptadine was initiated. The hospital course was prolonged and complicated by aspiration pneumonia, multiple deep vein thrombosis, and prolonged delirium. Higher amounts of Fentanyl and Propofol were required to maintain adequate sedation. The patient remained hypertensive, febrile, with signs of hyperreflexia, and clonus for seven days. Fentanyl was discontinued due to potential serotonergic additive effects. Rapid clinical signs of improvement were observed. It was ultimately discovered that the patient was using lysergic acid diethylamide (LSD). DISCUSSION: LSD is a widely used hallucinogen and a recognized cause of SS³. In the ICU, patients can be exposed to multiple serotonergic agents including opiates and antiemetics, thus, it is imperative clinicians are aware of which agents precipitate and prolong the course of SS. Moreover, each individual’s risk for developing and recovering from SS is dependent on several factors including age, liver, renal function, and genetic polymorphisms in the cytochrome P450 pathway. A thorough review of medications in the ICU may prevent further complications and result in a faster and favorable prognosis. CONCLUSIONS: Our case demonstrates a unique presentation of SS with a favorable outcome due to early suspicion of the diagnosis, recognition of serotonergic agents, and aggressive intervention. Reference #1: Wacker, D. (2017). Crystal Structure of an LSD-Bound Human Serotonin Receptor. Cell, 168(3), pp.377-389.e12. Reference #2: Greenier, E. (2014). Serotonin syndrome: fentanyl and selective serotonin reuptake inhibitor interactions. American Association of Nurse Anesthetists, 82(5), pp.340-5. Reference #3: Halberstadt, A. (2017). Hallucinogenic Drugs: A New Study Answers Old Questions about LSD. Current Biology, 27(4), pp.R156-R158. DISCLOSURES: No relevant relationships by Sujith Puskoor, source=Web Response No relevant relationships by Rebecca Saunders, source=Web Response No relevant relationships by Anita Singh, source=Web Response

Effect of variation in objective resource value on extreme male combat in a quasi-gregarious species, Anastatus disparis

BackgroundAggressive behaviour is widely observed in animal kingdom, which compete for resources such as territory, food and mates. Resource value is the most important non-strategic factor influencing fighting behaviour, and may vary among contests and contestants. Usually, contestants adjust their fighting behaviour when the resource value changes, and as potentially damaging and energetically costly, individuals of most species usually avoid conflict escalation. However, in a quasi-gregarious egg parasitoid, Anastatus disparis (Hymenoptera: Eupelmidae), mates are valuable resources and females mate only once; thus, males engage in frequently extreme combat behaviour to acquire mating opportunities, even in the absence of females. In this study, we attempted to test whether males of this species have the ability to adjust their fighting behaviour in response to changes in the objective value of female.ResultsOur results suggested that objective resource value in A. disparis is likely to be influenced by female mating status rather than by fecundity. Consistent with a number of empirical studies, A. disparis males adjusted their fighting behaviour according to the value of the contested resources: males significantly increased their fighting intensity to acquire mating opportunities with virgin females but decreased their fighting intensity for mated females. We also found that rather than chemical cues, visual cues and physical sexual contact appear to play a role in determining males’ ability to detect variation in female mating status.ConclusionsOur study suggested that although in this species, males have evolved extreme fighting behaviour and females are valuable resources, males do not always escalate fighting behaviour in competition for mating with a female. Valuable resources and variation in resource value were detected and estimated by A. disparis males, which then adjusted their fighting behaviour accordingly and to some extent avoided incoming fighting costs.

Adaptive learning and evolution framework of intelligent combat behavior modeling based on EXIT framework reasoning

The intelligent combat behavior modelling has always been a hot topic in the field of artificial intelligence and military. Aiming at the requirement of development of intelligent equipment in complex battlefield, this paper proposes an adaptive learning and evolution framework of intelligent combat behavior modeling based on EXIT framework reasoning, and provides theoretical, technical and methodological support for more efficient implementation of the evaluation and application verification of intelligent action plan.

Evaluation of MAV/UAV Collaborative Combat Capability Based on Network Structure

The collaborative combat of manned/unmanned aerial vehicles (MAVs/UAVs) is a popular topic in combat application research. It maximizes the autonomous combat capability of UAVs and the control capability of MAVs. Furthermore, it improves the comprehensive combat effectiveness. The quantitative description of intercommunication in different aircrafts along with the evaluation of the collaborative combat capability is an emphasis in military research. This paper analyzes the collaborative combat process. Node and edge models are established in the MAV/UAV collaborative network. The intercommunication and combat behaviors among combat entities are analyzed. Based on the information entropy, the effect of capability uncertainties on the collaborative combat is described quantitatively. An evaluation method of the MAV/UAV collaborative combat capability is proposed. Finally, an example is given to demonstrate the proposed model and evaluation method that prove its feasibility and effectiveness.

Examining the Every Student Succeeds Act's Impact on African American Students’ Mental Health Access

African American students from underserved communities throughout the United States are exposed to a variety of traumas, including community and intrafamilial violence. Far too often, members of the school-based staff misinterpret combative student behaviors, which are viewed as acts of defiance. However, the factors that contribute to academic and/or emotional problems are not properly contextualized. Ensuring that students have access to comprehensive mental health services is critical. Historically, school districts have depended heavily on federal resources to address the mental health needs of students from minority and low socioeconomic backgrounds. For this reason, examining the Every Student Succeeds Act's (ESSA's) new block grant program, the Student Support and Academic Enrichment Grant, is important. Under ESSA, several programs were consolidated or eliminated. The grant funds the Safe Schools/Healthy Students initiative, which focuses on mental health, among other issues. This article examines how a shift in federal policy could affect mental health access among African American students from underserved backgrounds.“We must, by including special school aid funds as part of our education program, improve the quality of teaching, training, and counseling in our hardest hit areas.”— Lyndon B. Johnson, January 8, 1964

Letter from the Editors

Letter from the Editors

Knowing Your Rights is Something, But Not Enough: Exploring Collective Advocacy and Rights to Treatment and Services for People Living with HIV in Tanzania

Citizen and collective advocacy is often regarded as a critical way to hold governments to account for the services they are expected to deliver and combat the marginalisation of certain groups. This article presents a qualitative analysis of the application of a “rightsbased” and advocacy approach as a means for People Living with HIV (PLWHIV) to claim their legislative rights to basic services such as education, and combat behaviour that is stigmatising. Data was obtained from a project in Northern Tanzania that works with more than 40 self-help groups to empower them to claim their rights as stipulated in the 2008 HIV/AIDS Act. The findings suggest that knowing one’s rights does seem to enable groups to start asking questions about their entitlements to services. However, it is not enough for one to simply know their rights when their actions and responses are fundamentally limited by lack of resource and power, vague legislative commitments and weak local institutional capacity to respond. These findings have implications for the many social policy initiatives, which seek to use citizen or group-based advocacy to address discrimination or poor public service delivery.

Male-male lethal combat in the quasi-gregarious parasitoid Anastatus disparis (Hymenoptera: Eupelmidae)

Most animals employ aggressive behaviours to acquire resources such as food, territory and mates. Although mating is important for males, which typically exhibit competitive behaviours to gain mating opportunities, they generally tend to avoid conflict escalation; while extreme combat also occurs in some species and results in death. In this study, male-male lethal combat behaviour in Anastatus disparis was examined (Hymenoptera: Eupelmidae) by investigating the characteristics of fighting and the factors that influence fighting intensity in this species. Male fight intensity in A. disparis increased with both competitor density and female presence, while it was not influenced by the relatedness among male competitors. By comparing the frequency of received attacks between injured and non-injured males, we found that the former were more vulnerable to attack. In contrast to death due to lethal attack, death that occurs as a result of A. disparis combat may be the cumulative effect of injuries sustained over repeated competitive encounters. Combined with the biological characters of A. disparis, we discuss potential factors contributing to the evolution of fatal conflict in this species.

Armed group institutions and combatant socialization

Ex-combatants who fought with the Salvadoran Army during El Salvador’s 1980–92 civil war often recall being ‘captured’, rather than recruited, suffering beatings and humiliation in the course of training, and fighting without a sense of purpose or direction. Those who served with rebel forces, by contrast, recall fatigue and frustration with new routines, but seldom hazing or abuse; most also recalled deep, ongoing instruction about the purpose and goals of the war. This comparison highlights the broad variation in armed groups’ formal institutions for socialization, a topic that political scientists have only recently begun to examine in depth. The Salvadoran case also emphasizes some shortcomings of the existing literature, which may elide the differing effects of different formal institutions, treat individual institutions as operating independently on combatant behavior, and/or fail to map complex causal processes intervening between institutions and behavior. This article takes as its starting point the observation that many armed group institutions – including recruitment, military training, political training, and disciplinary regimes – are components of the process known more generally as ‘combatant socialization’. Examining specific institutional processes associated with combatant socialization allows for the generation of more refined and specific theories of combatant socialization as both a causal variable and an outcome. At the same time, treating armed group institutions as related elements of a broader process, rather than as fully separate institutions, may also advance understandings of the effects of these institutions. I demonstrate that the implementation and content of formal institutions for socialization varied significantly both across and within groups in El Salvador; building on this analysis, I lay out several potential directions for comparative research.

Synchrotron scanning reveals the palaeoneurology of the head-butting Moschops capensis (Therapsida, Dinocephalia).

Dinocephalian therapsids are renowned for their massive, pachyostotic and ornamented skulls adapted for head-to-head fighting during intraspecific combat. Synchrotron scanning of the tapinocephalid Moschops capensis reveals, for the first time, numerous anatomical adaptations of the central nervous system related to this combative behaviour. Many neural structures (such as the brain, inner ear and ophthalmic branch of the trigeminal nerve) were completely enclosed and protected by bones, which is unusual for non-mammaliaform therapsids. The nearly complete ossification of the braincase enables precise determination of the brain cavity volume and encephalization quotient, which appears greater than expected for such a large and early herbivore. The practice of head butting is often associated with complex social behaviours and gregariousness in extant species, which are known to influence brain size evolution. Additionally, the plane of the lateral (horizontal) semicircular canal of the bony labyrinth is oriented nearly vertically if the skull is held horizontally, which suggests that the natural position of the head was inclined about 60–65°to the horizontal. This is consistent with the fighting position inferred from osteology, as well as ground-level browsing. Finally, the unusually large parietal tube may have been filled with thick conjunctive tissue to protect the delicate pineal eye from injury sustained during head butting.

Reproductive Biology of the Brazilian Lancehead, Bothrops moojeni (Serpentes, Viperidae), from the State of São Paulo, Southeastern Brazil

Bothrops moojeni inhabits riparian forests and adjacent open, wet areas in the Brazilian Cerrado. We address several aspects of the reproductive biology of a population from southeastern Brazil, including sexual maturation and dimorphism, male and female reproductive cycles, and sperm storage. We also provide the first record of male-male combat behavior in the wild. We sampled specimens held in the scientific collection of the Butantan Institute, Sao Paulo, Brazil. After macroscopic analyses and dissections, we collected the testes of males and the posterior uterus of females showing uterine muscular twisting for microscopic analyses. Males < 54.5 cm and females < 58.0 cm were sexually immature. Mature females are larger than males, although male-male combat is reported for this species. Male-male fighting and copulation occur during late summer in the wild. Histological analysis of the testes confirmed that sperm production occurs simultaneously with those reproductive events. Females showed an extended period of vitellogenesis, from February to November (late summer to spring). We observed stored sperm in the female reproductive tract during autumn. Because mating is not synchronous with ovulation, sperm storage is an obligatory component of the reproductive cycle of B. moojeni. Ovulation begins in August (winter) but most females with the presence of embryos in the oviducts occurred from January to March (summer). Parturition in captivity occurred in February, confirming that births are concentrated in the summer. Given that the Cerrado is highly fragmented in southeastern Brazil, studies on the reproductive biology of additional B. moojeni populations might provide useful information regarding intraspecific variation in reproduction in pit vipers.