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Background: Clinician managers can play a crucial role in healthcare organizations, including hospitals, by combining their clinical expertise with managerial responsibilities. They bring valuable insights and firsthand experience of patient care to managerial positions, contributing to improved patient outcomes and hospital performance. However, they face unique challenges that require careful attention and solutions. Aim: This review aims to critically discuss the role of clinicians as managers, the challenges that they face, and how they exercise their influence in hospital settings. Key findings: The role of clinicians as managers is critical for effective leadership and delivery of high-quality patient care. Described as a two-way window, clinician managers bridge the gap between medicine and management by combining clinical expertise with managerial skills in a hybrid leadership approach. Studies have shown a positive impact on hospital performance, including enhanced quality care, improved patient outcomes, and potentially better financial performance. In addition, they play a vital role in fostering interdisciplinary collaboration and boosting staff engagement. However, challenges such as identity conflicts, and limited formal training, are present, especially for first-time managers. Conclusion: Adapting to the dual role of clinician and manager demands a mindset shift and the development of new skills, necessitating strategic support. This includes leadership education, organizational support, mentoring, and collaborative models to empower clinician managers. Targeted training programs, formal mentoring, and peer support networks equip them with essential skills, while workload management, well-being initiatives, and a culture of balance foster success and growth.

Penile cancer, a rare but highly morbid disease, primarily manifests as squamous cell carcinoma (PSCC) originating from the squamous cells of the glandular and preputial skin. Late-stage diagnosis is common due to social stigma, psychological barriers, and nonspecific initial symptoms, resulting in poor overall survival rates, especially in metastatic cases. This case report illustrates a 38-year-old man with advanced metastatic PSCC, showcasing severe systemic manifestations and delayed presentation of the disease. Despite aggressive treatment options, the patient opted for palliative care, succumbing to the disease months after his diagnosis. Risk factors for PSCC include HPV infection, phimosis, chronic inflammation, and lifestyle factors, with higher prevalence in regions of low socioeconomic status. The psychological and sexual burden of penile cancer is significant, impacting patients’ well-being, mental health, and quality of life. In conclusion, efforts to reduce the stigma associated with penile cancer are crucial to prompt early diagnosis and treatment initiation. Encouraging seeking medical attention for symptoms can enhance the chances of recovery and minimize the need for invasive treatments. Addressing the psychosocial impact of the disease is imperative for holistic patient care.

Background: Apert syndrome is a type 1 acrocephalosyndactyly, a rare syndrome characterized by the presence of multiple craniosynostoses, dysmorphic facial manifestations, and syndactyly of hand and feet. It affects 1:100.00 of birth and is the second most common of syndromic craniosynostosis. Molecular genetic tests that identify the heterozygous pathogenic variant in FGFR2 genes - identical with Apert syndrome cost too high to be applicable in developing countries. Therefore, the diagnosis of Apert syndrome should be suspected from the clinical findings. Three cases from the Community of Indonesian Apert Warrior Group were collected. These series were based on medical and surgical records. We obtained the patient characteristics from the phenotypic manifestations only. Case report: We present a case of a newborn baby girl, with similar anatomical findings, such as skull shape abnormality, midface hypoplasia, intraoral disfigurement, and hands and feet deformities that resemble Apert Syndrome. Our series presents similar Apert syndrome characteristics, such as typical craniofacial dysmorphic with symmetrical syndactyly of both upper and lower extremities. These clinical findings are essential to establish an initial diagnosis of Apert Syndrome.

Background: Liver cancer is a global health concern, with overweight and obese individuals exhibiting an increased risk of its development. Understanding the interplay between obesity-related factors and liver cancer incidence is crucial for early prediction and intervention.Aim: The aim of this investigation was to construct and validate an extreme gradient boosting (XGBoost) based machine learning model for the purpose of establishing a one-year liver cancer risk prediction system specifically tailored to overweight and obese patients. In addition, this study sought to compare the predictive performance of the XGBoost model with those of a random forest model and a logistic regression model, while also identifying the most influential predictive features for liver cancer incidence.Methods: A comprehensive retrospective analysis was conducted on MIMIC III data comprising 2,354 patients. To predict the risk of liver cancer development, three machine learning models were developed: XGBoost, random forest, and logistic regression. Feature selection was executed using a stepwise regression procedure encompassing both forward selection and backward elimination.Results: The stepwise regression technique unveiled 14 predictive factors for liver cancer incidence. Among the patient cohort, 132 individuals developed liver cancer within a year of follow-up, while 2,222 did not. Notably, most liver cancer cases occurred in male patients (60%). Statistically significant differences were observed between patients with liver cancer and those without, in terms of age, gender, total bilirubin, platelet, albumin, chloride, potassium, sodium, prothrombin time (PT) and alanine aminotransferase (ALT). The XGBoost model exhibited an impressive area under the receiver operating characteristic curve (AUROC) of 99%, Random Forest (RF) of 99%, and Logistic Regression (LR) of 90%. In a multivariate analysis, total bilirubin, creatinine levels, age, gender, ALT, alkaline phosphate (ALP), PT, calcium, and chloride emerged as independent predictors for liver cancer incidence.Conclusion: The XGBoost model demonstrated superior predictive performance when compared to the RF and LR models. If corroborated through prospective studies, the XGBoost model may prove to be a valuable tool for the early prediction of liver cancer risk in overweight or obese individuals. Such predictive capabilities could, in turn, facilitate the implementation of timely preventive interventions against liver cancer.

The drug and biopharmaceutical enterprises play a pivotal part in transforming healthcare through the incident and delivery of creative cures and remedies. This item explores the key facets of these areas, stressing their impact on healthcare.Pharmaceuticals, outlined as wealthy secondhand in the diagnosis, situation, or stop of disease, aim to restore, correct, or refine everyday functions. On the other hand, biopharmaceuticals (or biologicals) circumscribe sugars, proteins, nucleic acids, living containers, or tissues and are curative devices that arise natural beginnings to a degree persons, animals, or microorganisms. In contrast to common pills combined with synthetic processes, biopharmaceuticals are primarily acquired through unaffected processes, containing extraction from living constructions or production utilizing alteration of genetic material Table 1.•    Some usual biopharmaceuticals, originally gleaned from animals or persons, are immediately created through biotechnological advancements.•    For instance, healing insulin, previously gleaned from porcine pancreatic islets, is immediately made utilizing alteration of genetic material in yeast (Saccharomyces cerevisiae) or E. coli.•    Biopharmaceuticals caused by alteration of genetic material usually fall into three classifications:•    Substances nearly equal to the body’s own key signaling proteins.•    Monoclonal antibodies look like those caused by apiece human immune plan against bacteria.•    Receptor builds (fusion proteins) established uniformly happening receptors connected to the immunoglobulin frame.Examples includeFrom living systems: Whole blood and ancestry parts, organs and fabric transplants, stem containers, antibodies for inactive immunization, polluted microbiota, human bosom milk, and human reproductive containers.Produced by recombinant DNA: Blood determinants, fabric plasminogen activators, hormones, hematopoietic growth determinants, interferon, interleukin-located produce, vaccines, monoclonal antibodies, tumor loss determinants, therapeutic enzymes.•    Key dispute Pharmaceutical manufacturing•    Biopharmaceuticals•    Healthcare strike•    Innovative medicines•    Therapeutic fragments•    Recombinant DNA technologies•    Personalized cure•    Gene medicines•    Regulatory processes.

Today’s need for renewable energy combined with modern societies' reliability on on-demand power leads us to find solutions that can store excess or produce directly to storage for later use. A MOlecular Solar Thermal (MOST) based on norbornadiene/quadricyclane(NBD/QC) does the latter with an isomeric photoswitching molecule pair. The theoretical studies of molecular solar thermals (MOST) provide a needed understanding of potential synthetic candidates. We have investigated an array of more complex solvation models for the norbornadiene/quadricycle (NBD/QC) photoswitch and the impacts of the models on the first absorption energy. Our results have been obtained with various density functional theoretical methods and basis sets.

Forеst dеgradation has bеcomе incrеasingly pronouncеd in rеcеnt timеs due to shifts in climatе pattеrns and prolongеd drought pеriods. This invеstigation aims to cultivatе high-quality vеgеtation and gain insights into thеir еcophysiological rеsponsеs undеr conditions of watеr strеss. Spеcifically, wе conductеd еxpеrimеnts on 6-month-old individuals from two dеciduous spеciеs (Quеrcus subеr and Cеratonia siliqua) and two conifеrs (Tеtraclinis articulata and Cеdrus at-lantica), subjеcting thеm to watеr strеss conditions. Wе mеasurеd and analyzеd both thе basic (Ψb) and minimum (Ψm) lеaf watеr potеntials, factoring in climatic variablеs for all four forеst spеciеs. Our findings rеvеal that Quеrcus subеr еxhibits morе nеgativе valuеs, with a basic lеaf watеr potеntial of -0. 42 MPa and a minimum lеaf watеr potеntial of -1. 43 MPa, comparеd to thе othеr studiеd forеst spеciеs. On thе contrary, Cеdrus atlantica displays lеss nеgativе valuеs for thе minimum lеaf watеr potеntial, rеcording -0. 89 MPa. Thеsе outcomеs еnablе us to idеntify thе spеciеs displaying grеatеr rеsiliеncе against watеr strеss and climatе fluctuations. Nеvеrthеlеss, they also prompt broadеr inquiriеs into thе undеrlying mеchanisms govеrning watеr utilization in forеst flora. 

Light is not only a primary energy source, but it is also one of the environmental factors that affect plant growth and development. Common bean (Phaseolus vulgaris L.) is commonly produced in association with maize as subordinate intercrops in the Sidama region. Under such a production system, the shade effect may limit the photosynthetic and nitrogen-fixing capacity of common beans. The objective of the current study was to assess how inoculation and shade affect the ability to fix nitrogen and yield components of common beans. Three common bean varieties (Hawassa dume, Nassir, and Ibbado), two shade levels (open and 25% shade) as well as two levels of inoculation (uninoculated and inoculated) were used for these purposes. The experiment was set up in factorial randomized complete block design (RCBD) in four replications. In this experiment, Rhizobium inoculation and shade significantly (p < 0.05) affected the number of pods plant-1 and the number of seeds pod-1. The inoculated treatment produced the maximum number of pods plant-1 (14.02) and the lowest number of pods plant-1 (10.95) was obtained from uninoculated treatments. The results also showed that the inoculated Hawassa dume variety from the open treatments derived the maximum percentage of N from N2 fixation, whereas the non-inoculated Ibbado variety from the 25% shade treatments derived the lowest percentage of N. Common bean grown on full light had significantly greater N content than shade.

The superposition of non-linear waves in space refers to the phenomenon where two or more waves overlap and combine to form a new wave pattern. Non-linear waves are characterized by their ability to interact with each other, leading to complex behaviors that are not observed in linear wave systems. Understanding the stability and behavior of the superposition of non-linear waves in space is crucial in various fields such as physics, engineering, and oceanography.When non-linear waves superpose, their interactions can lead to a range of behaviors, including wave breaking, formation of solitons (localized wave packets), and the generation of harmonics. The stability of the superposition is determined by the balance between the non-linear effects and dispersive effects, which can either stabilize or destabilize the wave pattern. In addition, the behavior of non-linear waves in space is influenced by external factors such as boundaries, dissipation, and external forcing.In this paper, we study the behavior and characteristics of waves when they interact with each other. Superposition refers to the phenomenon where multiple waves combine to form a resultant wave. In the case of linear waves, this superposition occurs according to the principles of linear superposition, which states that the displacement or amplitude at any point is the algebraic sum of the displacements or amplitudes of the individual waves.Understanding the superposition of linear waves in space has various applications in fields such as physics, engineering, acoustics, optics, and signal processing. By studying how waves interact and combine, researchers can gain insights into wave propagation, interference patterns, wave reflections, diffraction, and other phenomena that occur when waves meet.

The current study aimed to investigate the effect of using a pilates exercise program on improving body mass index and body composition of non-physically active working women. The participants of the study were (16) working women at the University of Basrah, Iraq. A pre-posttest was utilized to collect the data, (after a 12-week cycle of exercises) in Pilates groups, the results of the study showed that there were statistically significant differences at (α ≤ 0.05) in the women’s mean scores on body mass index and body composition. The study concluded that the pilates exercise program is effective in the improvement of body mass index and body composition of non-physically active working women.

Systemic lupus erythematosus (SLE) is a chronic inflammatory multisystem disorder that commonly affects females during their reproductive years. It is characterized by the presence of autoantibodies and immune complex deposition, the etiology is not known but the interaction of an environmental agent in a genetically susceptible individual is thought to be fundamental. SLE most frequently involves the skin, joints, lungs, heart, kidney, and neuropsychiatric manifestations that may occur during the course of the disease. Mood disorders among SLE patients, particularly depression, are common and important psychiatric manifestations of the disease, in addition to their high incidence and possible deleterious influence on disease progression, so early identification and treatment of depression may have a significant influence on the patient’s quality of life.

Introduction: The functional anatomy of the myocardium allows envisioning that it initiates and ends at the origin of the great vessels. In our research, we have always considered that it should have a point of attachment to allow its helical rotation to fulfill the fundamental movements of shortening-torsion (systole) and lengthening-detorsion (suction), which once found, was called the cardiac fulcrum. Materials and methods: A total of 31 hearts, arising from the morgue and slaughterhouse were used: 17 corresponded to bovids and 14 were human. Anatomical and histological studies were performed. The heart was fixed in 10% buffered formalin. Hematoxylin-eosin, Masson’s trichrome staining technique, and 4-micron sections were used for the histological study, and 10 % formalin was used as a buffer. Results: The anatomical investigations have revealed that all the hearts (bovids and humans) have myocardial support whose histological structure in the analyzed specimens presents with an osseous or chondroid-tendinous character. In this structure, which we have called the cardiac fulcrum, are inserted the myocardial fibers at the origin and end of the band, which correspond to the continuous myocardium coiled as a helix.Conclusion: This description of the fulcrum would end the problem of lack of support of the myocardium to fulfill its function of suction/ejection.

Known since antiquity, migraine is a complex primary disorder, an episodic painful Autonomic Nervous System (ANS) storm, generally following the stress/post-stress phase. Despite exhaustive study of neuropeptides, neurochemicals, molecules, neurogenetics, neuroimaging along with animal and human experiments over the last 50 years, the scientific basis of migraine remains unknown. Straddling eight decades from Cortical Spreading Depression (CSD) to Calcitonin-Gene Related Peptide (CGRP) and its antagonists, exponentially increasing data have failed to create a gestalt synthesis. This article lays cohesive and robust fundamental principles for the comprehension and management of migraine. The continuum between migraine and non-congestive Primary Open-Angle Glaucoma (POAG), Normal Tension Glaucoma (NTG), or Low-Tension Glaucoma (LTG) is advancing. The case of sustained remission of migraine attacks (> 75%) over 3 years - 5 years with ocular hypotensive topical Bimatoprost Ophthalmic Solution (BOS) 0.3% in an N-of-1 trial in 3 patients with refractory migraine is presented. A cause-effect-adaptive process underlies the ANS-stress/post-stress-linked biology of migraine. Vasopressin-serotonin-norepinephrine ‘homeostatic-adaptive system’ Lowers Intraocular Pressure (IOP), while enhancing anti-stress, antinociception, vasomotor, and behaviour control functions, thereby selectively decreasing algogenic neural traffic in the ophthalmic division of trigeminal nerve (V1), and, raising the threshold to develop migraine. Striking migraine headache-aborting feature of vomiting is also likely linked to a several hundred-fold increase in arginine-vasopressin secretion. Eye-cover tests and self-ocular digital displacement are essential to studying the visual aura. Real-time physical displacement of Scintillating Scotoma (SS) and floating ‘stars’ is reported. The basis of spontaneous onset and offset, self-limited duration of migraine attacks, as well as female preponderance, and age/menopause decline in prevalence, are elucidated. Intraocular implants with long-term ocular hypotensive effects, including bimatoprost, are the future of migraine management. Controlled trials are required to establish the migraine-preventive effect of topical bimatoprost, a revolutionary advance in neuroscience.

Introduction: In our fast-paced world, children’s dietary habits and behaviour are increasingly concerning, with a tendency toward indulging in sweets and snacks. Insights are derived from observations of 20 children at a crèche facility.Temptation of sweets: Children’s inherent attraction to sweet and salty snacks challenges maintaining a healthy diet. Excessive consumption can lead to health issues, recognizing the pivotal role parents and caregivers play in guiding children toward healthier choices.Significance of a balanced diet: A well-rounded and nutritious diet is crucial for a child’s physical and mental development. Providing fruits, vegetables, whole grains, and lean proteins is essential.Role of activities: Diversifying a child’s routine with engaging activities is a powerful strategy to redirect their focus from unhealthy snacks. Sports, arts, outdoor play, and educational games promote physical fitness, creativity, and cognitive development, contributing to a well-balanced lifestyle.Strategies for encouraging healthy choices:•    Lead by example: Modelling healthy habits inspires children to adopt similar behaviour.•    Educate about nutrition: Imparting knowledge about the nutritional value of foods equips children to make informed choices.•    Make healthy options accessible: Stocking the kitchen with nutritious snacks makes it convenient for children to opt for healthier alternatives.•    Limit unhealthy choices: Setting clear limits on sugary snacks helps children develop moderation and self-control.•    Create a fun and active environment: Fostering an enjoyable environment involves family outings, games, and making exercise a natural part of daily life.Results: Encouraging results were observed among the 20 children. Two children, aged around 12, demonstrated awareness of healthy habits. Excluding these two, others showed positive changes in behaviour towards sweets and snacks through activities and counselling.Conclusion: Maintaining a balance between a child’s consumption of sweets and snacks and engaging in diverse activities is crucial for overall development. A combination of nutritious choices and engaging activities guides children toward a path of health and happiness

Cardiovascular disease (CVD), including coronary artery disease and stroke, is the leading cause of death worldwide. Advances in primary and secondary prevention of CVD have improved patient prognoses and outcomes, however, it is imperative that the clinician and patient engage in early risk factor screening and preventive management of modifiable risk factors for CVD. In addition to blood lipid and blood pressure lowering medications, aspirin has been a long-standing therapy targeted to the prevention of CVD based on its antiplatelet and anti-inflammatory activity. However, recent articles and reports on updates to clinical guidelines for the primary prevention of CVD have resulted in confusion about aspirin recommendations. This review aims to assess the latest guidance on aspirin in CVD prevention and how to identify appropriately at-risk patients who may benefit from low-dose aspirin therapy as part of their CVD preventive healthcare choices. Additionally, this review will provide practical application guidance about clinician-patient conversations to clearly explain the benefits and risks of aspirin use and ensure a patient-centric decision to initiate aspirin therapy.

Accumulated condylomas are exophytic tumors with a warty and hyperkeratosic surface due to the Human papillomavirus (HPV). Its prevalence in children is difficult to estimate due to limitations in epidemiological data. Its recurrent character is found in 30% of patients. Its management is very complex in children because of skin fragility. Circumcision is an operation consisting of the removal of part of the foreskin. This practice is done either with a simple knife or a pair of non-aseptic scissors which can be a source of contamination including HPV (Condyloma). Traditional circumcision does not seem to be reported in the literature as a mode of contamination. We report a case of genital condyloma in a child 2 years after circumcision. This is a 2-year-old male with no medical history but with a surgical history of circumcision that was brought by his parents in dermatological consultation for papular lesions accumulated on the penis. At the interrogation, we found the notion of recent circumcision performed by a tradithérapeute. The physical examination finds a good general condition. Dermatological examination reveals on the glans of multiple papules, exophitic, with warty and hyperkeratotic surface, of normal skin color. Furthermore, the physical examination of both parents was normal. The diagnosis of accumulated condyloma secondary to probable circumcision was retained before the clinical appearance of the lesions. Two electrocoagulation sessions spaced one month apart under local anesthesia were the treatment with a favorable evolution.

Antibiotic resistance is a growing global crisis, straining healthcare systems and leaving us with limited options to combat drug-resistant bacteria. This retrospective, cross-sectional study examines the prevalence of antibiotic resistance patterns among urinary tract infections (UTIs) in Al-Shifa Hospital’s medical departments in comparison with non-medical departments using data from microbiology laboratory archives over a one-year period. From the examined urine cultures about 25% were obtained from internal medicine departments and double the number was obtained from non-medical departments. The positive rate was around 35% and about two-thirds of the samples were collected from female patients. Among all departments, Enterobacteriaceae spp. were found to be the most frequently isolated uropathogens, accounting for 80% of cases. However, resistance rates varied depending on the specific organism and antibiotic used. For instance, E. coli showed a resistance rate of only 5% against meropenem, while amoxicillin-clavulanic acid exhibited a resistance rate exceeding 95%.Importantly, the study revealed a significant disparity in resistance rates between medical and non-medical departments, specifically concerning third-generation cephalosporins. In internal medicine departments, resistance rates were alarmingly high, with cefotaxime, ceftriaxone, and ceftazidime showing resistance rates of 75%, 75% and 66.5% respectively. In contrast, non-medical departments displayed lower resistance rates, approximately 60%, 60% and 40%, respectively.In summary, this research sheds light on the escalating problem of antibiotic resistance in UTIs and emphasizes the discrepancy in resistance rates between medical and non-medical departments. Urgent efforts are required to address this issue and find effective solutions to prevent the rise of untreatable bacterial infections.

Biochemical systems are analytically investigated after encoding the properties of the dynamics, which rule the time evolution of the transition properties, using some Markov models, such as the Hierarchical Markov-State Models. The present paper is aimed at analytically writing the (finite) Markov chain originating from the considered Markov models. Within this framework, the interaction with the environment is considered, and the ergodicity of the systems obtained from numerical simulation is controlled and compared with the qualities of the Markov chain. The (von Neumann) conditions to be imposed on the Bloch equations for the biomaterial structures to be described analytically in a consistent way are governed. The formalisms of the ’heat bath’ and that of the control of the numerical errors ensure the good measure-theoretical framework and the ergodicity of the finite chain, respectively.The finite Markov chains are investigated and the analytical expressions are presented, after which the Hierarchical Markov-State-Model provides the time evolution of the transition probabilities in biochemical systems.The notion of heat bath is used to describe the interactions of the biomaterial with the environment and thus to control the uses of the projection operators in the Markovian processes where the appropriate measure is defined; the stochastic equations allow one to obtain the wanted measure from the probability spaces.The cases in which a violation of the Markov property of the process occurs, i.e. in open systems, or dissipative processes are also considered. Furthermore, in complex molecules in biological systems, these features are investigated to be possibly even more dramatic. As far as molecular processes are concerned, this occurrence is associated with the appearance of chaotic effects with certain characteristics of potential surfaces: rather than the technique of isocommittors, the method of projectors in measure spaces is used for the Nakajima-Zwanzig paradigm for the density operator; this latter method complementary compares the time-convolution-less technique.The finite Markov chains are finally proven to be ergodic after the control of the numerical errors which provide the Sinai-Markov partitions to be applied for the analysis of the measure space of the Markov chain, that is, one endowed with a Hilbert measure. The von Neumann conditions are therefore newly demonstrated to be apt to be applied to the Bloch equations for biomaterial structures after the use of the notion of heat bath, from which the measure space arises.The qualities of the Hierarchical Markov-Sate Models which bring the analytical expression of the time evolution of probabilities of biomaterials are therefore newly analytically studied.

Background: Dysgerminomas, account for only 1% - 2% of all malignant ovarian neoplasms.Objective: This case report aims to present a rare occurrence of dysgerminoma in a pediatric patient, highlighting the clinical characteristics, diagnosis, and management.Case presentation: We present a case of dysgerminoma in a 12-year-old girl who presented with a three-week history of pelvic pain and progressive abdominal swelling. Physical examination revealed a distended abdomen with evident suprapubic fullness, and a palpable abdominopelvic mass measuring approximately 20 weeks in size. Imaging studies confirmed the presence of a solid heterogeneous mass originating from the pelvis. The patient underwent a right salpingo-oophorectomy without complications. Histological examination coupled with an immunohistochemical study confirmed the diagnosis of dysgerminoma. The patient had an uneventful postoperative course and was discharged without adjuvant treatment. Regular follow-up visits, physical examinations, ultrasound scans, and lactate dehydrogenase assays were initiated for monitoring. Conclusion: Prompt recognition and appropriate surgical intervention, followed by regular monitoring, are crucial for optimal outcomes in pediatric dysgerminoma cases.

To reach such a consistent theory which contains the quantum field theory of particle physics and Einstein’s theory of gravitation as limiting cases, one may proceed in the following way: Standard quantum field theory just ignores the effects of gravity. This is justified in many cases due to the weakness of gravitational interactions at the presently accessible scales. In a first step beyond this approximation, one may consider an external gravitational field that is not influenced by the quantum fields. Here one may think of sources of gravitational fields that are not influenced by the quantum fields under consideration, as high-energy experiments in the gravitational field of the earth or quantum fields in the gravitational field of dark matter and dark energy. This approach amounts to the treatment of quantum field theory on curved spacetimes. The problem of quantization in curved spacetimes is now clearly visible. In Minkowski spacetime, there is a large group of symmetries that enforces a particular choice of vacuum by demanding the vacuum to be invariant. Such a criterion is absent for a general spacetime (M,g). We therefore do not know which state to choose as the vacuum. One might hope that the different prescriptions might be unitarily equivalent such that it doesn’t matter which state one takes to define the theory. Sadly this is not the case: The Stone-Von Neumann theorem is no longer valid for systems with an infinite amount of degrees of freedom. This means that unitarily inequivalent representations of the canonical commutation relations will arise, and it is not clear which equivalence concept representation is the physical one. In the second section of this chapter, we review the notions of Cauchy surfaces and global hyperbolicity.