Research has shown that lowering brain temperature may have good results in heart attack patients. Lowering brain temperature may be a promising treatment for stroke patients. The Excel Cryo Cooling device drops brain temperature by cooling the blood in arteries in the neck. The device is a neck collar with a cooling pack which when shaken can reach low temperature within seconds. The collar is placed around the patient's neck and the cooling pack is applied to the front of the neck and held in place. This device provides stable cooling irrespective of participant size or weight. The objective of this study is to test the value of using Excel Cryo Cooling device in dropping brain temperature in 3 different groups of adult participants:

i. Healthy adult volunteers, ii. Adult participants with normal body temperature in intensive care unit iii. Adult participants with fever in intensive care unit

To investigate effectiveness, safety and ease of application of Cryo Collar to rapidly reduce core brain temperature, the study will recruit 8 healthy volunteers, 10 adult normothermic participants and 10 adult sick febrile participants from Neurocritical Care ICU in The Ohio State University Wexner Medical Center. Before placing the collar around participant's neck, the investigators will record the participant's ear temperature and heart rate as a baseline. An Excel Cryo Collar will be placed around the participant's neck. After activating the cooling element, the investigators will place it within the neck collar.

The participant's ear temperature will be recorded every 5 minutes. The investigators will replace the cooling element every 20 minutes and continue to record the participant's ear temperature every 5 minutes. A total of 6 cooling elements will be used over 2 hours. The heart rate and blood pressure of the participant will be checked and recorded every 20 minutes when cooling element is replaced. The participant's bedside shivering assessment scale (BSAS) will also be recorded during the study.

Five adult sick febrile participants will receive 2 rounds of cooling procedure each 2 hours long.

The investigators will analyze data gathered from the study in 2 different ways:

First, the investigators will run descriptive statistics in three groups of participant to find out the following variable: Average temperature drop, average time to mild therapeutic hypothermia and change in temperature at the end of study.

Second, the investigators will compare the difference in achieving temperature drop among three groups by comparing mean values of temperature drop in three groups.

Inclusion Criteria:

• Male or female 18-60 years of age
• Computed Tomography Angiography (CTA) image results show no narrow in carotid artery (not applied to healthy volunteers)
• Be able to accept cooling procedure at least 2 hours
• Provide informed consent.

Exclusion Criteria:

• Patients with increased intracerebral pressure (ICP), intracerebral hemorrhage (ICH) and carotid artery stenosis
• Receiving external ventricular drainage
• Taking anti-febrile medications within 4 hours
• Females who are pregnant or breastfeeding
• Subjects who have arrhythmia, other serious cardiac disease, or low blood pressure
• Subject has a higher body mass index (BMI>35)
• Receiving jugular IV catheter
• Skin wound around the neck