Design and prototyping of a low-cost portable mechanical ventilator

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. [10]).This paper describes the design and prototyping of a low-cost portable mechanical ventilator for use in mass casualty cases and resource-poor environments. The ventilator delivers breaths by compressing a conventional bag-valve mask (BVM) with a pivoting cam arm, eliminating the need for a human operator for the BVM. An initial prototype was built out of acrylic, measuring 11.25 x 6.7 x 8 inches (285 x 170 x 200 mm) and weighing 9 lbs (4.1 kg). It is driven by a stepper motor powered by a 14.8 VDC battery and features an adjustable tidal volume of up to 900 mL, adjustable breaths per minute (bpm) of 5-30, and inhalation to exhalation time ratio (i:e ratio) options of 1:2, 1:3 and 1:4. Tidal volume, breaths per minute and i:e ratio are set via user-friendly knobs, and the settings are displayed on an LCD screen. The prototype also features an assist-control mode and an alarm to indicate over-pressurization of the system. Future iterations of the device will be fully calibrated to medical standards and include all desired ventilator features. Future iterations will be further optimised for low power-consumption and will be designed for manufacture and assembly. With a prototyping cost of only $420, the bulk-manufacturing price for the ventilator is estimated to be less than$100. Through this prototype, the strategy of cam-actuated BVM compression is proven to be a viable option to achieve low-cost, low-power portable ventilator technology that provides essential ventilator features at a fraction of the cost of existing technology. Keywords: Ventilator, Bag Valve Mask (BVM), Low-Cost, Low-Power, Portable and Automatic.by Stephen K. Powelson.S.B

Interface-driven ferromagnetism within the quantum wells of a rare earth titanate superlattice

Here we present polarized neutron reflectometry measurements exploring thin film heterostructures comprised of a strongly correlated Mott state, GdTiO$_3$, embedded with SrTiO$_3$ quantum wells. Our results reveal that the net ferromagnetism inherent to the Mott GdTiO$_3$ matrix propagates into the nominally nonmagnetic SrTiO$_3$ quantum wells and tracks the magnetic order parameter of the host Mott insulating matrix. Beyond a well thickness of 5 SrO layers, the magnetic moment within the wells is dramatically suppressed, suggesting that quenched well magnetism comprises the likely origin of quantum critical magnetotransport in this thin film architecture. Our data demonstrate that the interplay between proximate exchange fields and polarity induced carrier densities can stabilize extended magnetic states within SrTiO$_3$ quantum wells.Comment: 5 pages, 4 figure

Evaluation of the optical switching characteristics of erbium-doped fibres for the development of a fibre Bragg grating sensor interrogator

A polling topology that employs optical switching based on the properties of erbium-doped fibres (EDFs) is used to interrogate an array of FBGs. The properties of the EDF are investigated in its pumped and un-pumped states and the EDFs’ switching properties are evaluated by comparing them with a high performance electronically controlled MEM optical switch. Potential advantages of the proposed technique are discussed. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Evaluation of the Long-Lasting Insecticidal Net Interceptor LN: Laboratory and Experimental Hut Studies against Anopheline and Culicine Mosquitoes in Northeastern Tanzania

Long lasting insecticidal nets (LN) are a primary method of malaria prevention. Before new types of LN are approved they need to meet quality and efficacy standards set by the WHO Pesticide Evaluation Scheme. The process of evaluation has three phases. In Phase I the candidate LN must meet threshold bioassay criteria after 20 standardized washes. In Phase II washed and unwashed LNs are evaluated in experimental huts against wild, free flying anopheline mosquitoes. In Phase III the LN are distributed to households in malaria endemic areas, sampled over three years of use and tested for continuing insecticidal efficacy. Interceptor® LN (BASF Corporation, Germany) is made of polyester netting coated with a wash resistant formulation of alpha-cypermethrin. Interceptor LN was subjected to bioassay evaluation and then to experimental hut trial against pyrethroid-susceptible Anopheles gambiae and An. funestus and resistant Culex quinquefasciatus. Mosquito mortality, blood feeding inhibition and personal protection were compared between untreated nets, conventional alpha-cypermethrin treated nets (CTN) washed 20 times and LNs washed 0, 20 and 30 times. In Phase I Interceptor LN demonstrated superior wash resistance and efficacy to the CTN. In the Phase II hut trial the LN killed 92% of female An. gambiae when unwashed and 76% when washed 20 times; the CTN washed 20 times killed 44%. The LN out-performed the CTN in personal protection and blood-feeding inhibition. The trend for An. funestus was similar to An. gambiae for all outcomes. Few pyrethroid-resistant Cx. quinquefasciatus were killed and yet the level of personal protection (75-90%) against Culex was similar to that of susceptible An. gambiae (76-80%) even after 20 washes. This protection is relevant because Cx. quinquefasciatus is a vector of lymphatic filariasis in East Africa. After 20 washes and 60 nights’ use the LN retained 27% of its initial insecticide dose. Interceptor LN meets the approval criteria set by WHO and is recommended for use in disease control against East African vectors of malaria and filariasis. Some constraints associated with the phase II evaluation criteria, in particular the washing procedure, are critically reviewed

Highly effective yet simple transmembrane anion transporters based upon ortho-phenylenediamine bis-ureas

Simple, highly fluorinated receptors are shown to function as highly effective transmembrane anion antiporters with the most active transporters rivalling the transport efficacy of natural anion transporter prodigiosin for bicarbonate

A cognitive approach to user perception of multimedia quality: An empirical investigation

Whilst multimedia technology has been one of the main contributing factors behind the Web's success, delivery of personalized multimedia content has been a desire seldom achieved in practice. Moreover, the perspective adopted is rarely viewed from a cognitive styles standpoint, notwithstanding the fact that they have significant effects on users’ preferences with respect to the presentation of multimedia content. Indeed, research has thus far neglected to examine the effect of cognitive styles on users’ subjective perceptions of multimedia quality. This paper aims to examine the relationships between users’ cognitive styles, the multimedia quality of service delivered by the underlying network, and users’ quality of perception (understood as both enjoyment and informational assimilation) associated with the viewed multimedia content. Results from the empirical study reported here show that all users, regardless of cognitive style, have higher levels of understanding of informational content in multimedia video clips (represented in our study by excerpts from television programmes) with weak dynamism, but that they enjoy moderately dynamic clips most. Additionally, multimedia content was found to significantly influence users’ levels of understanding and enjoyment. Surprisingly, our study highlighted the fact that Bimodal users prefer to draw on visual sources for informational purposes, and that the presence of text in multimedia clips has a detrimental effect on the knowledge acquisition of all three cognitive style groups

Association of Aerobic Fitness and Metabolic Syndrome in Male Firefighters

Metabolic syndrome has been shown in numerous studies to be related to a higher incidence of coronary artery disease. A study by Jurca and coworkers (Med. Sci. Sports Exerc 36(8):1301-1307, 2004) found a relationship between aerobic fitness and the prevalence of metabolic syndrome in a group of men enrolled in the Aerobics Center Longitudinal Study (ACLS). In addition, recent work in our lab (Int J Exerc Sci 2(1): S43, 2009) has supported these findings. However, research exploring this relationship is still lacking in male firefighters, whose leading cause of line-of-duty deaths is heart attacks. Purpose: To further evaluate the association of metabolic syndrome and aerobic fitness in male fire fighters. Methods: As part of an annual physical exam, 210 male fire fighters (average age = 36) underwent evaluation of risk factors associated with metabolic syndrome as defined by NCEP III. These include the presence of three or more of the following: Waist Circumference \u3e 40 , HDL Cholesterol \u3c 40 mg/dL, Triglycerides \u3e 150 mg/dL, Blood Glucose \u3e 110 mg/dL, and Resting Blood Pressure \u3e 130/85 mm Hg. Aerobic Fitness was determined by estimating VO2max from time on treadmill during a Bruce protocol. Results: The subjects were ranked and divided into quartiles based on VO2max. All data were analyzed using a Chi Square test (p \u3c 0.05). Prevalence of metabolic syndrome increased significantly across quartiles as aerobic fitness declined. Conclusion: These data suggest that as aerobic fitness improves, the likelihood of male firefighters having metabolic syndrome decreases