Mach-Zehnder-based measurement of light emitting diodes temporal coherence

Objectives: The main objective of this work is to validate a Mach-Zehnder based interferometric method to measure the temporal coherence length of broadband finite size light sources such as Light Emitting Diodes (LEDs), and give a qualitative value of the temporal coherence length of white LEDs, for which nor their spectral width neither their emission peak wavelength are clearly defined. Motivation: Low-coherence light sources such as LEDs have opened many possibilities in applications in which using lasers introduces coherent noise (speckle) that hinders the performance of interferometric measurement techniques. The coherence length is an important characteristic of light sources for scientific applications related to diffraction, holography, tomography, or interferometry. The spatial coherence of a source depends on the distance from the source to the observation plane and its size, while the temporal coherence is related to the emission spectral width and the emission peak wavelength. Therefore, the temporal coherence is a characteristic of each source. Methodology and results: In this work, we use a Mach-Zehnder interferometer for the first time to measure the coherence degree and the temporal coherence length of quasi-monochromatic LEDs. We validate the technique by comparing the results to those obtained directly from the spectrum. Then, we use the tested interferometric method to measure the temporal coherence length of a white LED, for which neither the width of the spectrum nor the emission peak wavelength, are clearly defined. In this case, the Wiener-Khinchin theorem is used to validate the interferometric technique. A very interesting property of the method is that the temporal coherence length is obtained from a single measurement, without needing to perform a scanning. This method can be used also for other non-coherent sources such as halogen lamps, pulsed lasers, and so on. The obtained results will improve the characterization of light sources and the applications dealing with physical optics and electromagnetic interference. © 2022 The Author

Fluid therapy in neurotrauma: basic and clinical concepts

The patient with head trauma is a challenge for the emergency physician and for the neurosurgeon. Currently traumatic brain injury constitutes a public health problem. Knowledge of the various therapeutic strategies to provide support in the prehospital and perioperative are essential for optimal care. Rapid infusion of large volumes of crystalloids to restore blood volume and blood pressure quickly is now the standard treatment for patients with combined TBI and HS The fluid in patients with brain and especially in the carrier of brain injury is a critical topic; we present a review of the literature about the history, physiology of current fluid preparations, and a discussion regard the use of fluid therapy in traumatic brain injury and decompressive craniectomy

Effect of cervical collars on intracranial pressure in patients with head neurotrauma

Trauma patients are at high risk of cervical and associated injuries. The standard protocol includes immobilization of the cervical spine in a polytrauma as it will help to prevent spinal injuries in the prehospital settings. Hard cervical collar (or alternatives) is routinely used until the cervical spine clearance is obtained . In patients with traumatic brain injury avoiding any kind of maneuver may lead to increased intracranial pressure

Post-traumatic cerebellar infarction due to vertebral artery foramina fracture: Case report

Posttraumatic cerebral infarction is an uncommon cause of morbidity and mortality and many studies have highlighted that trauma needs to considered as causative factor for cerebellar infarction. We present a case of cerebellar infarction in a 35 year old young patient secondary to vertebral fracture involving the vertebral foramen and vertebral artery injury. CT scan cervical spine showed C2-3 fracture on left side with fracture extending into the left vertebral foramen. A CT scan angiogram could not be performed because of poor neurological status. Possibly the infarction was due to left vertebral artery injury. Without surgical intervention prognosis of these patients remain poor. Prognosis of patients with traumatic cerebellar infarction depends on the neurological status of the patient, intrinsic parenchymal damage and more importantly extrinsic compression of the brainstem by the edematous cerebellar hemispheres

Unilateral traumatic hemorrhage of the basal ganglion and bihemisferic cerebral infarction

Among the various injuries caused by the cerebral tramatic lesion are trau- matic brain contusions. Hemorrhagic contusions of the basal ganglia are unusual. Different injuries such as cranial fractures, epidural hemorrhage, subdural hematoma, subarachnoid hemorrhage among others may be associated with brain contusions. In some cases traumatic brain injury arises. We present a case of a patient with unilateral cerebral contusion associated with bihemispheric cerebral infarction

Non traumatic fractures of the lumbar spine and seizures: Case report

Injury-induced seizures may appear clinically asymptomatic and can be easily monitored by the absence of trauma and post-ictal impairment of consciousness. Patients with epilepsy have a higher risk of compression fractures, leading to serious musculoskeletal injuries, this type of non-traumatic compression fractures of the spine secondary to seizures are rare lesions, and is produced by the severe contraction of the paraspinal muscles that can achieve the thoracic spine fracture. Seizures induced lesions may appear clinically asymptomatic and can be easily monitored by the absence of trauma and post-ictal impairment of consciousness. We present a case report

The five preferences for post-traumatic SAH

Acute traumatic brain injury is a worldwide public health crisis. Post-traumatic subarachnoid hemorrhage (SAH) is a finding that is present at a frequency of 40% according to data from American TCDB (1,2). Among the mechanisms that have been implicated as causes of post-traumatic SAH is the cortical bleeding through the subarachnoid space. It is estimated that the incidence of post-traumatic SAH is 11% to 60% in patients with traumatic brain injury. The brain CT is considered a technique with good sensitivity, economical and available in many hospitals worldwide. We have reviewed the literature and found some imaging characteristics of post-traumatic subarachnoid hemorrhage. We have called “the five preferences for post-traumatic SAH”

Toll like receptor-3 ligand poly-ICLC promotes the efficacy of peripheral vaccinations with tumor antigen-derived peptide epitopes in murine CNS tumor models

BACKGROUND: Toll-like receptor (TLR)3 ligands serve as natural inducers of pro-inflammatory cytokines capable of promoting Type-1 adaptive immunity, and TLR3 is abundantly expressed by cells within the central nervous system (CNS). To improve the efficacy of vaccine strategies directed against CNS tumors, we evaluated whether administration of a TLR3 ligand, polyinosinic-polycytidylic (poly-IC) stabilized with poly-lysine and carboxymethylcellulose (poly-ICLC) would enhance the anti-CNS tumor effectiveness of tumor peptide-based vaccinations. METHODS: C57BL/6 mice bearing syngeneic CNS GL261 glioma or M05 melanoma received subcutaneous (s.c.) vaccinations with synthetic peptides encoding CTL epitopes- mEphA2 (671–679), hgp100 (25–33) and mTRP-2 (180–188) for GL261, or ovalbumin (OVA: 257–264) for M05. The mice also received intramuscular (i.m.) injections with poly-ICLC. RESULTS: The combination of subcutaneous (s.c.) peptide-based vaccination and i.m. poly-ICLC administration promoted systemic induction of antigen (Ag)-specific Type-1 CTLs expressing very late activation antigen (VLA)-4, which confers efficient CNS-tumor homing of vaccine-induced CTLs based on experiments with monoclonal antibody (mAb)-mediated blockade of VLA-4. In addition, the combination treatment allowed expression of IFN-γ by CNS tumor-infiltrating CTLs, and improved the survival of tumor bearing mice in the absence of detectable autoimmunity. CONCLUSION: These data suggest that poly-ICLC, which has been previously evaluated in clinical trials, can be effectively combined with tumor Ag-specific vaccine strategies, thereby providing a greater index of therapeutic efficacy

Therapeutic hypothermia in brain trauma injury: controversies

Traumatic brain injury (TBI) is a common cause of death and disability in developed countries. It is a major cause of mortality in young patients worldwide. Intracranial hypertension is the cause of death in more than 80% of patients with TBI. When secondary lesions occur, start a number of mechanisms that increase the metabolic injury to brain tissue. Induction of hypothermia has been shown to alter the natural course of the disease process. The biological foundations suggest that hypothermia may have a potential benefit, although some publications have shown no improvement, it is clear that in a group of mostly young patients, early hypothermia may be beneficial. We present a practical review of the literature on this subject

Spontaneous chronic subdural hematoma in a young male patient: Case report

The chronic subdural hematoma is a common pathology in elderly patients. There is usually a history of head trauma. The diagnosis of chronic subdural hematomas in young patients is very rare and few cases have been reported in the literature. The authors present a case of a patient of 16 years old who presented headache of two months of evolution, which was conducted by tomography diagnosis of chronic subdural hematoma. The patient had no history of mild trauma. Surgical management was performed, showing a satisfactory evolution