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A realistic, durable, and low-cost training model for percutaneous renal access using ballistic gelatin

Jonathan Mark Ewald, Loma Linda University School of Medicine, Loma Linda California, California, USA, Julie Won-ching Cheng, Shawn Michael Engelhart, Michael Chevalier Wilkinson, Mohammad Hajiha, Hillary Wagner, D. Duane Baldwin, Department of Urology, Loma Linda University, Loma Linda California, California, USA, Loma Linda University School of Medicine, Loma Linda California, California, USA, Loma Linda University School of Medicine, Loma Linda California, California, USA, Department of Urology, Loma Linda University, Loma Linda California, California, USA (+2 others)
2019 Turkish journal of urology  
The purpose of this study was to design and implement a realistic, durable, and low-cost training model for percutaneous renal access. Ballistic gelatin mixed with radiographic contrast was poured into surgical gloves to create a radio-dense renal collecting system. The collecting system model was then embedded in a pure ballistic gelatin block resting upon a clear acrylic glass base. Finally, the model was covered by a visually opaque polyurethane foam cover with chalk sticks positioned to
more » ... late ribs. Experienced attending urologists and interventional radiologists, urology residents, and medical students used the model to access the upper, middle, and lower renal calyces under fluoroscopic guidance. Outcomes included model durability, realism rated by participants on a visual analogue scale, and cost. The ballistic gelatin model was durable and anatomically realistic. Each model sustained over 200 needle punctures with no significant compromise in structural integrity or any contrast leakage. Attending and resident physicians considered it to provide an accurate simulation of renal access and medical students and residents considered the model to be a practical training modality (residents 8.4/10 vs. medical students 9.4/10). The total cost for one model was $60. The ballistic gelatin collecting system provided a realistic, durable, and low-cost renal access training model. This could allow trainees to develop skills without compromising patient safety.
doi:10.5152/tud.2018.43569 pmid:30668307 pmcid:PMC6342578 fatcat:eun4qomdl5gallhecpxz7qiaua

Observations of the 1989 Loma Prieta earthquake

Peter Marks
1990 Bulletin of the New Zealand Society for Earthquake Engineering  
This report has been modified from one presented to the Wellington City Council and sets out observations and conclusions gained from a visit to San Francisco and the area affected by the Loma Prieta Earthquake  ...  CONCLUSION The Loma Prieta earthquake was a large earthquake but not a big one.  ...  APPENDIX LOMA PRIETA EARTHQUAKE CONCLUSIONS AND RECOMMENDATIONS The biggest impact of the Loma Prieta earthquake (M=7.1) at 5:04 P.M. on October 17, 1989 on water and sewage lifelines was the loss  ... 
doi:10.5459/bnzsee.23.4.235-238 fatcat:oi3vltycgbatrklw3izqdghb2i

Encrypting network traffic [chapter]

Mark Lomas
1994 Lecture Notes in Computer Science  
Encryption may be used to maintain the secrecy of information, to help detect when messages have been tampered with, or to prove the identity of the originator of a message. Why, we might ask, are so many messages still sent unencrypted? There are several possible explanations. Many people are unaware of the potential benefits of encrypting messages before transmission. Alternatively they may not be aware how insecure their computers are; for example most of the computers in use within the
more » ... ter Laboratory here in Cambridge transmit user's passwords unen.crypted so that they may be read by anybody who cares to monitor network transmissions; this is typical of many if not most computer networks. Another possibility is that the cost of encrypting network traffic is considered too high for the potential benefits. If people are unaware of the benefits or do not realise that their machines are insecure then they should be educated so that they can make an objective decision as to whether or not they should encrypt their messages. In this paper I aim to address the idea that encrypfion may be too costly; I believe that many forms of transmission may be encrypted at a much lower cost than many people realise and that their decisions regarding the use of encryption may change if they are shown the true cost. Network Overheads Before we can evaluate the cost of encrypting network traffic we need some measure against which we can compare this cost. The network over which we will send this traffic imposes costs of its own. If the time taken to encrypt a message is much greater than the time taken to transmit it then encryption will cause a noticeable degradation in the performance of the network. If we find that the transmission is much more costly than the encryption then the encryption will cause very little degradation in performance. In such a case I would suggest that encryption is worthwhile. For my measure of network performance I chose to analyse the round-trip time for a series of transmissions. These measurements were performed between two VAXstation-2000 computers connected by an Ethernet local area network. Both machines were running the Ultrix operating system and they used the TCP/IP protocol to manage their transmissions. My experiments indicate that we cannot describe the performance of such a network configuration in terms of a single number. This was not particularly surprising since I had expected network performance to depend upon a variety of factors; these include the load upon the network and the load upon the machines themselves. Although the round-trip time did not vary greatly I achieved a much higher throughput when the packet size was large rather than small. For example, typically it would take 46 seconds to transmit and receive 10,000 packets of length 128 bytes (a total of 20,000 packets). When the packet size was increased to 1,024 bytes then the total time increased only slightly to 50.5 seconds. These represent a throughput of 56,000 and 406,000 bytes per second respectively; the larger packet size resulted in 7.3 times as much throughput.
doi:10.1007/3-540-58108-1_9 fatcat:4dn4jc2sobbtpi2kxi6zox4w54

You Can't Take It with You [chapter]

Mark Lomas
2002 Lecture Notes in Computer Science  
doi:10.1007/3-540-45807-7_25 fatcat:nevixoxfnfc6dbgjjt4wbxjzs4

Pico Without Public Keys [chapter]

Frank Stajano, Bruce Christianson, Mark Lomas, Graeme Jenkinson, Jeunese Payne, Max Spencer, Quentin Stafford-Fraser
2015 Lecture Notes in Computer Science  
Pico is a user authentication system that does not require remembering secrets. It is based on a personal handheld token that holds the user's credentials and that is unlocked by a "personal aura" generated by digital accessories worn by the owner. The token, acting as prover, engages in a public-key-based authentication protocol with the verifier. What would happen to Pico if success of the mythical quantum computer meant secure public key primitives were no longer available, or if for other
more » ... asons such as energy consumption we preferred not to deploy them? More generally, what would happen under those circumstances to user authentication on the web, which relies heavily on public key cryptography through HTTPS/TLS? Although the symmetric-key-vs-public-key debate dates back to the 1990s, we note that the problematic aspects of public key deployment that were identified back then are still ubiquitous today. In particular, although public key cryptography is widely deployed on the web, revocation still doesn't work. We discuss ways of providing desirable properties of public-key-based user authentication systems using symmetric-key primitives and tamperevident tokens. In particular, we present a protocol through which a compromise of the user credentials file at one website does not require users to change their credentials at that website or any other. We also note that the current prototype of Pico, when working in compatibility mode through the Pico Lens (i.e. with websites that are unaware of the Pico protocols), doesn't actually use public key cryptography, other than that implicit in TLS. With minor tweaks we adopt this as the native mode for Pico, dropping public key cryptography and achieving much greater deployability without any noteworthy loss in security.
doi:10.1007/978-3-319-26096-9_21 fatcat:ewasulxynbfgdp7nccaolli5fe

Probing serpin reactive-loop conformations by proteolytic cleavage

Wun-Shaing W. CHANG, Mark R. WARDELL, David A. LOMAS, Robin W. CARRELL
1996 Biochemical Journal  
The plasticity of the reactive loop was illustrated by proteolytically modified structures in which cleavage of the scissile reactive bond, denoted as P1-P1h [13] , resulted in a marked and irreversible  ...  The findings were more marked for the heterologous binary complex with increased accessibility of the P7-P6 bond (52 %), no significant difference at P8-P7 (27 %) and the remaining 21 % showing no cleavage  ... 
doi:10.1042/bj3140647 pmid:8670081 pmcid:PMC1217096 fatcat:weyiiwmorrbujjq2og375uzury

Remote booting in a hostile world: to whom am I speaking? [Computer security

Mark Lomas, Bruce Christianson
1995 Computer  
Acknowledgment Part of this work was carried out while Mark Lomas was a visiting research fellow at the University of Hertfordshire.  ...  Mark Lomas is a research fellow at the University of Cambridge Computer Laboratory. His research interests include  ... 
doi:10.1109/2.362630 fatcat:cmudr2qlufbx7j7lhhxprre35e

Fire at high latitudes: Data-model comparisons and their consequences

Euripides Kantzas, Mark Lomas, Shaun Quegan
2013 Global Biogeochemical Cycles  
hydraulic properties of organic soil and incorporates boreal PFTs, and its soil temperature profiles and permafrost extent perform well when compared to observations . [12] The SDGVM [Woodward and Lomas  ...  Marked differences are found between the properties of fires observed by satellites and their representations in three state-of-the-art land surface models, two of which are embedded in Intergovernmental  ... 
doi:10.1002/gbc.20059 fatcat:p2qcvvho6ff7pphmnwxkstjony

Immunohistochemical localization of inflammatory cells and cell cycle proteins in the gills of Loma salmonae infected rainbow trout (Oncorhynchus mykiss)

Mark D. Powell, M. Naveed Yousaf, Karina Juhl Rasmussen, Berndt Köllner, Jun Zou, Chris Secombes, David J. Speare
2014 Fish and Shellfish Immunology  
University of Nordland where the immunohistochemistry work was undertaken and to Joanne Daley for laboratory assistance at the Atlantic Veterinary College, University of Prince Edward Island where the Loma  ...  The marked increase in numbers of CD8 positive cells in the hyperplastic lesions indicated the involvement of cytotoxic T cells in the immunoreaction to Loma salmonae in trout.  ...  In conclusion, within Loma salmonae induced hyperplastic lesions in rainbow trout gills, there appears to be marked expression of PCNA and, albeit to a lesser extent, some caspase 3 activity [26] .  ... 
doi:10.1016/j.fsi.2014.06.004 pmid:24979224 fatcat:2ukg2j2jjzduvjnindya73digm

The statistical mechanics of community assembly and species distribution [article]

Colleen K. Kellya, Stephen J. Blundell, Michael G. Bowler, Gordon A. Fox, Paul H. Harvey, Mark R. Lomas, F. Ian Woodward
2010 arXiv   pre-print
Theoretically, communities at or near their equilibrium species number resist entry of new species. Such 'biotic resistance' recently has been questioned because of successful entry of alien species into diverse natural communities. Data on 10,409 naturalizations of 5350 plant species over 16 sites dispersed globally show exponential distributions for both species over sites and sites over number of species shared. These exponentials signal a statistical mechanics of species distribution,
more » ... ng two conditions. First, species and sites are equivalent, either identical ('neutral'), or so complex that the chance a species is in the right place at the right time is vanishingly small ('idiosyncratic'); the range of species and sites in our data disallows a neutral explanation. Secondly, the total number of naturalisations is fixed in any era by a 'regulator'. Previous correlation of species naturalization rates with net primary productivity over time suggests that regulator is related to productivity. We conclude that biotic resistance is a moving ceiling, with resistance controlled by productivity. The general observation that the majority of species occur naturally at only a few sites but only a few at many now has a quantitative [exponential] character, offering the study of species' distributions a previously unavailable rigor.
arXiv:1004.2271v1 fatcat:2myy2zy5sjgidngb25dzy4ks4i

Fungal Mineral Weathering Mechanisms Revealed Through Direct Molecular Visualization [article]

Arunima Bhattacharjee, Odeta Qafoku, Jocelyn A Richardson, Lindsey N Anderson, Kaitlyn Schwarz, Lisa M Bramer, Gerard X Lomas, Daniel J Orton, Zihua Zhu, Mark H Engelhard, Mark E Bowden, William C Nelson (+4 others)
2021 bioRxiv   pre-print
Soil fungi facilitate the translocation of inorganic nutrients from soil minerals to other microorganisms and plants. This ability is particularly advantageous in impoverished soils, because fungal mycelial networks can bridge otherwise spatially disconnected and inaccessible nutrient hotspots. However, the molecular mechanisms underlying fungal mineral weathering and transport through soil remains poorly understood. Here, we addressed this knowledge gap by directly visualizing nutrient
more » ... ion and transport through fungal hyphae in a mineral doped soil micromodel using a multimodal imaging approach. We observed that Fusarium sp. DS 682, a representative of common saprotrophic soil fungi, exhibited a mechanosensory response (thigmotropism) around obstacles and through pore spaces (~12 μm) in the presence of minerals. The fungus incorporated and translocated potassium (K) from K-rich mineral interfaces, as evidenced by visualization of mineral derived nutrient transport and unique K chemical moieties following fungal induced mineral weathering. Specific membrane transport proteins were expressed in the presence of minerals, including those involved in oxidative phosphorylation pathways and transmembrane transport of small molecular weight organic acids. This study establishes the significance of fungal biology and nutrient translocation mechanisms in maintaining fungal growth under water and nutrient limitations in a soil-like microenvironment.
doi:10.1101/2021.10.01.462718 fatcat:2h2lgspwfbfsld6zihxpt57tj4

Intracellular tortuosity underlies slow cAMP diffusion in adult ventricular myocytes

Mark Richards, Oliver Lomas, Kees Jalink, Kerrie L. Ford, Richard D. Vaughan-Jones, Konstantinos Lefkimmiatis, Pawel Swietach
2016 Cardiovascular Research  
Aims 3 ′ ,5 ′ -Cyclic adenosine monophosphate (cAMP) signals in the heart are often confined to concentration microdomains shaped by cAMP diffusion and enzymatic degradation. While the importance of phosphodiesterases (degradative enzymes) in sculpting cAMP microdomains is well established in cardiomyocytes, less is known about cAMP diffusivity (D cAMP ) and factors affecting it. Many earlier studies have reported fast diffusivity, which argues against sharply defined microdomains. Methods and
more » ... esults [cAMP] dynamics in the cytoplasm of adult rat ventricular myocytes were imaged using a fourth generation genetically encoded FRET-based sensor. The [cAMP]-response to the addition and removal of isoproterenol (b-adrenoceptor agonist) quantified the rates of cAMP synthesis and degradation. To obtain a read out of D cAMP , a stable [cAMP] gradient was generated using a microfluidic device which delivered agonist to one half of the myocyte only. After accounting for phosphodiesterase activity, D cAMP was calculated to be 32 mm 2 /s; an order of magnitude lower than in water. Diffusivity was independent of the amount of cAMP produced. Saturating cAMP-binding sites with the analogue 6-Bnz-cAMP did not accelerate D cAMP , arguing against a role of buffering in restricting cAMP mobility. cAMP diffused at a comparable rate to chemically unrelated but similar sized molecules, arguing for a common physical cause of restricted diffusivity. Lower mitochondrial density and order in neonatal cardiac myocytes allowed for faster diffusion, demonstrating the importance of mitochondria as physical barriers to cAMP mobility. Conclusion In adult cardiac myocytes, tortuosity due to physical barriers, notably mitochondria, restricts cAMP diffusion to levels that are more compatible with microdomain signalling. ---
doi:10.1093/cvr/cvw080 pmid:27089919 pmcid:PMC4872880 fatcat:nu3tze4sbzczna7lpc6msc2ozy

Catalytic hydroacetylenation of carbodiimides with homoleptic alkaline earth hexamethyldisilazides

Merle Arrowsmith, Mark R. Crimmin, Michael S. Hill, Sarah L. Lomas, Myra Sae Heng, Peter B. Hitchcock, Gabriele Kociok-Köhn
2014 Dalton Transactions  
While the bimetallic assembly of 3 is unprecedented for an amidinate-based system, the Ba-N (6) In all cases a marked product inhibition effect was observed, as well as an increase in reactivity  ... 
doi:10.1039/c3dt53542h pmid:24434957 fatcat:gfzktt2qp5ddtgdsriijoxksii

2-IMMERSE

Ian Kegel, James Walker, Mark Lomas, Jack Jansen, John Wyver
2017 Adjunct Publication of the 2017 ACM International Conference on Interactive Experiences for TV and Online Video - TVX '17 Adjunct  
This demonstration will showcase a new approach to the production and delivery of multi-screen entertainment enabled by an innovative, standards-based platform developed by the EU-funded project 2-IMMERSE. Objectbased production enables engaging and interactive experiences which make optimal use of the devices available, while maintaining the look and feel of a single application. The 'Theatre at Home' prototype offers an enhanced social experience for users watching a live or 'as live'
more » ... t of a theatre performance, allowing them to discuss it with others who are watching at the same time, either in a different room or in a different home.
doi:10.1145/3084289.3089909 dblp:conf/tvx/KegelWLJW17 fatcat:hvrdqh33xvdnte7akzbuji3raa

The statistical mechanics of community assembly and species distribution

Colleen K. Kelly, Stephen J. Blundell, Michael G. Bowler, Gordon A. Fox, Paul H. Harvey, Mark R. Lomas, F. Ian Woodward
2011 New Phytologist  
Theoretically, communities at or near their equilibrium species number resist entry of new species. Such 'biotic resistance' recently has been questioned because of successful entry of alien species into diverse natural communities. • Data on 10 409 naturalizations of 5350 plant species over 16 sites dispersed globally show exponential distributions both for species over sites and for sites over number of species shared. These exponentials signal a statistical mechanics of species distribution,
more » ... assuming two conditions. First, species and sites are equivalent, either identical ('neutral') or so complex that the chance a species is in the right place at the right time is vanishingly small ('idiosyncratic'); the range of species and sites in our data disallows a neutral explanation. Secondly, the total number of naturalizations is fixed in any era by a 'regulator'. • Previous correlation of species naturalization rates with net primary productivity over time suggests that the regulator is related to productivity. • We conclude that biotic resistance is a moving ceiling, with resistance controlled by productivity. The general observation that the majority of species occur naturally at only a few sites, and only a few species occur at many sites, now has a quantitative (exponential) character, offering the study of species' distributions a previously unavailable rigor.
doi:10.1111/j.1469-8137.2011.03721.x pmid:21534968 fatcat:fojnewszuzdfvhi2x55kzfbrle
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