Concave - concave

 2024-06-18 12:43:40

Beamof a ship

Similar to S. aureus Panton-Valentine leukocidin, S. pseudintermedius produces a bicomponent leukotoxin (Luk-I) that is leukotoxic to polymorphonuclear white blood cells [32,33]. α-hemolysin and β-hemolysin are produced by S. pseudintermedius and can cause hemolysis of rabbit erythrocytes and hot–cold hemolysis of sheep erythrocytes [27,34,35]. The exfoliative toxin, Staphylococcus intermedius exfoliative toxin (SIET), plays an important role in canine pyoderma and dogs injected with SIET developed erythema, exfoliation, and crusting, which are characteristics of canine pyoderma [36]. Additional exfoliative toxins include ExpA and ExpB [37,38]. SECCANINE an enterotoxin, with variable prevalence in the S. pseudintermedius population and distinct from other staphylococcal enterotoxins, has the ability to induce vomiting and T-cell proliferation [39,40] Finally, similar to S. aureus, S. pseudintermedius has an accessory gene regulator (agr) quorum-sensing system that regulates expression of virulence factors in a population density–based manner [41].

While of course you can go outside the calculated ratio, IMHO you should have a very good reason and specific justification for a deviation of more than 15% either way. Use the list at the beginning of this article to justify your change.

Length and beamfor boat

Historical observations led to the development of 2 important diagnostic assays: the classic tube coagulase test (in which fibrinogen is converted to fibrin by staphylocoagulase or von Willebrand binding protein, i.e., “free coagulase”) and the slide coagulase assay (whereby fibrinogen is bound by clumping factor, i.e., “bound coagulase”) [1,2]. These assays (or derivatives of) are used to differentiate staphylococcal isolates that elaborate coagulase: coagulase-positive Staphylococcus species (CoPS), and those that do not: coagulase-negative Staphylococcus species (CoNS). This is an important distinction because, in general, CoPS are considered to be more pathogenic than CoNS.

* More beam gives more transverse stability, permitting a powerful rig to drive a boat faster, but also, excessive beam tends to lower diagonal stability so increasing pitch-poling. More beam also tends to allow more fore & aft pitching.

A motor catamaran can have less beam, with a clean flow between the hulls now taking prominence over high beam for sailing stability, so L/B ratios of 2.5 to 3 are now more appropriate.

Affiliation Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York, United States of America

Idealbeamtolengthratio

To some degree, the same effect on diagonal stability (as for Cats) will occur with excessive beam, but with a trimaran, the two hulls in the water will be closer so it’s also important to allow for good flow between them. So as very large racing tris can have slimmer hulls due to great length and low weight, they can have proportionally lower B/L ratios than smaller boats that need proportionally fatter central hulls just to support the displacement they need. After all, we cannot just change things in proportion, because the weight of things (such as crew, structure etc) will not automatically get smaller for a smaller boat .. in fact it proportionally and typically, gets greater! So smaller multihulls can often be harder to design than larger ones, where you have more space and volume to work with. The above observations led me to plot data from good boats and create this simple little formula that fits their B/L curve pretty well.

* Less beam brings the hulls closer together, reducing beam strength requirements and weight, but potentially adding to resistance from hull-flow interaction.

Copyright: © 2021 Carroll et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Interestingly, of a variety of virulence factors assayed (e.g., β-hemolysin, clumping factor, coagulase, DNase, protein A, and lipase), only protein A production was significantly different between S. pseudintermedius isolates recovered from healthy and infected dogs and was expressed in more isolates recovered from infected animals (1.4% versus 14.2%) [30]. Therefore, host factors likely play an important role in disease and disease severity. Predisposing factors to SSTIs in dogs include hypersensitivities, ectoparasites, endocrinopathies, and cornification abnormalities [15]. Other factors that may contribute to the development of infection in colonized dogs include medical/surgical procedures or immunosuppressive disorders [7].

Staphylococcus aureus is the archetype CoPS and an important human pathogen [3]; however, several CoPS, most associated with animals, have been described [1,2] (Table 1). One CoPS of emerging clinical importance is Staphylococcus pseudintermedius, a member of the Staphylococcus intermedius group (SIG) (Table 1 and Fig 1). S. pseudintermedius is a significant pathogen in canines, an agent of infections in humans, and is the focus of this “Pearl”.

Length and beamin meters

Beam also has a huge effect on stability. But the designer Jan Gougeon (then of West Systems) was an inventive guy, so he approached this design in a non-conventional way. To achieve his first criteria .. “a fast non demountable weekend catamaran”, he needed to address the obvious lack of stability in other ways. A low rig could work with low weight, that would then allow very slim, fast hulls. Then he added water ballast to help keep the windward side down …. and finally, a masthead float to prevent the boat from turning turtle, where she would stay like virtually all other multihulls do IF that happens. In this case, it was rather often as unfortunately, most sailors were not ready to adapt to this new way of sailing and with capsizes happening too quickly for most, only a dozen or so were sold. But I did get to try the boat and felt the concept did work in the sense that the boat IS fast and also comfortable & dry, as with such long, narrow hulls, there is very little disturbance of the surface water so spray is minimal and even if the hulls are pretty close, they are too slim to create any significant cross-hull wake- interference.

SBF, the most common form of canine pyoderma and predominantly a result of S. pseudintermedius infection, is the primary reason for antimicrobial use in small animal practice [42–44]. Guidelines for managing canine SBF have been developed [45]. Conversely, no guidelines exist for managing human S. pseudintermedius infections. However, given its ability to elaborate toxins and virulence factors orthologous to those produced by S. aureus, human infections are often managed based upon culture-directed therapy.

Length and beamchart

A significant challenge to treating S. pseudintermedius is the emergence of methicillin (β-lactam) resistance, which results from acquisition of penicillin-binding protein 2a (PBP2a; encoded by mecA) [46]. Recent (within 1 month) administration of β-lactams or fluoroquinolones is associated with development of MRSP infection in canines [47]. Since the initial phenotypic description of MRSP in the 1980s [48], the frequency of MRSP has increased at an alarming rate. In one academic veterinary medical center in the United States (US), MRSP rates increased from <5% in 2001 to approximately 30% in 2008 [49] and, anecdotally, is reported to have reached 40% in some regions of the US [50]. MRSP prevalence in the human population remains largely unknown possibly because of potential misidentification as S. aureus, and breakpoints for detecting mecA-mediated resistance in S. aureus are inaccurate for S. pseudintermedius and can result in false susceptibility [10,11,49,51].

The lesson here is: If you choose to go outside the norm, fully understand the implications and work around them. You cannot ignore them and still expect success. If the designer failed at all with this radical G32 design, it was in not sufficiently educating new owners of the different sailing nuances needed to keep the boat on its feet.

Host associations based upon data presented in [5,6,67,70]. The animal sources of the type strains (Staphylococcus cornubiensis NW1T, Staphylococcus delphini DSM 20771T, Staphylococcus intermedius DSM 20373T, Staphylococcus pseudintermedius DSM 21284T, and Staphylococcus ursi MI 10-1553T) are indicated, and host associations of the different species are listed underneath. The human isolates likely reflect transmission from animal sources. In the case of S. cornubiensis, the type strain was recovered from a human [67]; however, a related isolate (2008-01-1056-2) was recovered from a dog [71], suggestive of an animal link. All members, with the notable exception of S. ursi, are coagulase positive.

MRSP dissemination is primarily driven by organisms belonging to ST68 and ST71 [50,52,53], and is concerning as these organisms are often MDR and typically only susceptible to agents restricted or rarely considered for use in veterinary medicine (e.g., daptomycin, linezolid, and vancomycin) [50,54,55]. Humphries and colleagues determined the antimicrobial susceptibility of 115 SIG isolates recovered from animals (56 canine isolates) and humans (n = 45) to 15 antimicrobials [55]. A total of 37 isolates harbored mecA and compared to mecA-negative isolates had decreased susceptibility to ciprofloxacin, clindamycin, doxycycline, erythromycin, and trimethoprim-sulfamethoxazole. Strikingly, human methicillin–resistant S. aureus isolates are often susceptible to doxycycline and trimethoprim-sulfamethoxazole [56,57]. This difference may facilitate identification in diagnostic laboratories where accurate identification methods are not available.

S. pseudintermedius colonizes and infects animals and is a zoonotic pathogen. Infections in canines are primarily SSTIs, and, in many cases, dogs have predisposing factors leading to infection. Human infections are also predominantly SSTIs and often, but not always, with documented canine involvement. The invasive potential of S. pseudintermedius and its complement of virulence factors—many of which mirror those associated with S. aureus—demonstrate this organism has the potential to cause serious disease. β-lactam resistance has emerged as a serious problem for canine health and is typically associated with MDR. Therefore, given the close relationship between canines and humans, S. pseudintermedius is an important candidate for One Health initiatives.

Humans are not the natural host but can be transiently colonized with S. pseudintermedius, including methicillin-resistant S. pseudintermedius (MRSP); however, the prevalence of human colonization is unknown as this organism can be misidentified as S. aureus [10,11]. In one study, enriched with individuals involved in the veterinary profession (42.5% of study participants), the prevalence (nasal colonization) of S. pseudintermedius in humans living in a household with a dog or cat was 4.1% (by contrast, the prevalence of S. aureus in humans was 27.7%), with lack of handwashing after handling household pets significantly associated with colonization [8]. In a subsequent study, 3.9% of small animal dermatologists surveyed were found to be colonized in the nares with MRSP [12]. Finally, Guardabassi and colleagues demonstrated that owners of dogs with pyoderma were more likely to be culture positive for S. pseudintermedius compared to persons without daily contact with dogs, but colonization was not documented at the time of a second sampling 2 months later, suggesting that long-term colonization is uncommon in humans (although dogs were treated with antimicrobials after the first sampling, and most no longer had purulent lesions at the second sampling) [13].

Infections predominantly involve the skin and skin structures (SST) of canines. SST infections (SSTIs) range from superficial bacterial folliculitis (SBF), characterized by multifocal areas of alopecia, follicular papules or pustules, serous crusts on the trunk and axillary areas, and epidermal collarettes to deeper infections such as furunculosis and cellulitis [7,14,15]. S. pseudintermedius is also a cause of otitis and urinary tract infections in dogs [16,17]. In a large case series from Italy [16], S. pseudintermedius constituted 76% of all Staphylococcus species recovered from dog and cat cultures, and 31.6% of those were MRSP. The most common presentations for MRSP isolates were otitis (36.8%), pyoderma (21%), cutaneous fistulae (15.8%), conjunctivitis (10.5%), postsurgical infections (10.5%), and prostatitis (5.3%). Almost all of the infections were seen in dogs, and the MRSP isolates belonged to several clones, most notably sequence type (ST) 71, with variable multidrug resistance (MDR) determinants.

Length and beamcalculator

To keep the rig low (mast is shorter than the boat), she uses 2 foresails that can be furled up fast. Those that still own one have learned to understand them and can enjoy their merits … but this is not a boat with reserve stability for sudden gusts, so you need to sail this boat more like a race dinghy and also reduce sail early. This further means that sailing at night when you cannot see squall warnings in the sky is best avoided unless the stars are truly out for you.

As noted, the above ratios refer to Sailing Craft. Without the heeling force of a sail, pure motor-tris and cats are not bound by the same needs.

Human respiratory infections (sinusitis, otitis, and pneumonia) are well described in the literature [11,19–22]. Kuan and colleagues described symptoms and findings in 4 patients with serious rhinosinusitis, and they reviewed the literature on this entity [21]. Symptoms of chronic rhinosinusitis occurred in all patients. A total of 3 of 4 patients had immunocompromising conditions. Sinus cultures revealed mixed pathogens, and prolonged antimicrobial therapy and surgical debridement were required for treatment. In a series of 33 patients with chronic rhinosinusitis, there was no difference in immunocompromising factors between patients with cultures positive with S. pseudintermedius and those that had other organisms [22], although dog ownership was more common in the S. pseudintermedius group. In addition, 27% of the isolates were MRSP and the authors emphasized the importance of identifying the etiology of rhinosinusitis and determining antimicrobial susceptibility to guide therapy even in immunocompetent patients.

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S. pseudintermedius virulence factors include cytotoxins, exfoliative toxins, superantigens, and cell wall–associated (CWA) proteins and are important in initiating and spreading infections such as SSTIs and evading the immune system, and many are orthologous to those elaborated by S. aureus [7,14,25,26]. Additionally, S. pseudintermedius has the ability to form biofilms [27]. Enzymes that play an important role include proteases and thermonucleases, and the promotion of plasma coagulation (i.e., coagulase activity) by von Willebrand binding protein is a key pathogenic trait [2,7,14,26]. In silico analysis of the S. pseudintermedius ED99 genome led to the prediction of 18 putative CWA proteins termed “Staphylococcus pseudintermedius surface proteins” (Sps) [25]. These proteins endow S. pseudintermedius with adherence properties and 2, SpsD and SpsL, facilitate adherence to proteins of the host extracellular matrix: fibronectin, fibrinogen, and cytokeratin 10 [28]. In a study that examined bone and joint infection pathophysiological mechanisms among non-S. aureus species, only S. pseudintermedius was able to adhere to human fibronectin in a bacterial adhesion assay, and adhesion rates were similar to those observed for S. aureus [29]. Protein A, a CWA surface protein, is a major S. aureus virulence factor that facilitates immune evasion by binding immunoglobulins, inhibiting opsonization and phagocytosis, and acts as a superantigen [26]. SpsP and SpsQ are S. pseudintermedius protein A orthologues and presumably serve an important role in pathogenesis given isolates recovered from infected dogs synthesize protein A more frequently compared to those recovered from healthy dogs [28,30,31].

For both Tris and Cats, there may be other factors that will change your design, but this gives a good starting and target point that’s based on both practical and justified design needs.

Affiliation Department of Pathology and Immunology, Washington University in St. Louis School of Medicine, St. Louis, Missouri, United States of America

* As smaller boats need proportionally more displacement due to crew and structural weight, they cannot have a very high L/b ratio as they then have insufficient displacement.

Hulls may need to be asymmetrical with a straighter side on the inside to avoid unfavorable hull wave interaction between them.

The most common manifestations of infections in humans are SSTIs including dog bite wounds [10,11,18,19]. Somayaji and colleagues described one of the largest series of human S. pseudintermedius infections among 24 patients (27 isolates) [19]. SSTIs that occurred in 18 patients and 2 invasive infections, including a bloodstream infection and a prosthetic joint infection, were described. After chart review, 4 patients were determined to be colonized and not infected. Diabetes, peripheral vascular disease, and cardiovascular disease were the most significant comorbidities among this cohort, and 95.4% of patients had contact with dogs. Most of the infections were polymicrobial (91.7%), and the infections were primarily mild to moderate in severity, allowing the patients to be managed in the outpatient setting. A total of 3 patients were infected with MRSP isolates, and all were MDR. These MDR isolates belonged to MRSP lineages ST71 and ST181. Serious wound infections in patients, including diabetic patients, caused by the specific S. pseudintermedius epidemic clone ST71-J-t02-II-III, were described by Starlander and colleagues [18]. Interestingly, the authors suggested indirect or direct patient-to-patient acquisition of the epidemic clone between patients was very likely. No animal source could be identified. Yarbrough and colleagues also documented several instances where S. pseudintermedius was recovered from human clinical specimens without documented animal exposure, although it is unclear if this reflects human-to-human transmission or an incomplete medical history [11].

For several years, a local skier/sailor owned a Stiletto 27 cat with a beam of 14ft, giving an L/B of 1.93, or close to the theoretical sweet spot.. Coming from a Hobie-cat background, he’d often fly a hull as the boat was quite light at 1100 lbs with cigar berths in each hull and an open tramp between. But after a strong gale rolled in and wrecked it on shore, he saw a new Gougeon 32 announced and without much thought, bought one. The central cuddy looked cosy and the slim 32ft hulls sounded fast. But this boat was designed to be trailerable without dismantling, so she only has the beam of a Hobie cat …. 8’ 4” … so her L/B ratio is an outlandish 3.84 !! .. nearly half the beam of what ‘the sweet spot’ would indicate. Well, by day 3, its new owner had already capsized it and without much knowledge of how to right it, suffered a chilly 4 hour ordeal. (He found out the hard way that ‘tacking with water-ballast on one side’ is full of perils and is really not for lake sailing as you cannot switch the water in time).

* More beam requires stronger connecting beams (called akas on trimarans), aggravated by the two hulls potentially being now be in different waves

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Length and beamformula

The taxonomy and host associations of SIG members have been redefined by molecular typing methods (Fig 1). In 2 seminal studies, all isolates recovered from dogs, cats, and humans were identified as S. pseudintermedius, and thus S. pseudintermedius (not S. intermedius) was revealed as the common agent of canine pyoderma [4–6]. It is a component of the normal skin microbiota of dogs, and one review cites, based upon the literature, canine carriage rates per body site of: nose, arithmetic mean 31% (range, 16% to 64%); mouth, arithmetic mean 57% (range, 42% to 74%); perineum–rectum, arithmetic mean 52% (range, 28% to 72%); and groin, arithmetic mean 23% (range, 16% to 38%) [7]. Carriage rates in noncanine species, such as cats and horses, appear to be much lower than in dogs, with only 6.8% of cats colonized compared to 46.2% of dogs [8,9].

Citation: Carroll KC, Burnham C-AD, Westblade LF (2021) From canines to humans: Clinical importance of Staphylococcus pseudintermedius. PLoS Pathog 17(12): e1009961. https://doi.org/10.1371/journal.ppat.1009961

For a powered trimaran, overall beam should also be reduced or the motion will become uncomfortable. (With a sailing tri, the boat is heeled with one ama out, but with a motor tri, all three hulls are immersed so wave action on the boat would be too severe if the boat is too wide). Amas (pontoons) now need to be narrow but deep, as a slow gentle roll of slightly greater amplitude, is more comfortable than a short quick one. These amas (now only 40-50% of the main hull length), seem best with their center about 60-70% aft of the main hull length and need to be of fine section and relatively deep with the connecting bridge arched high above any waves, so that neither ama or aka-bridge will slam when re-entering a wave. L/b ratios of all 3 hulls can be at their most efficient, namely 13-16 at the waterline. The amas are now more like permanent training wheels and with a much longer central hull and no heeling force from sails, diagonal stability is no longer something to consider. Overall beam will depend on maintaining a clean flow between the main hull and the shorter slim amas, that need to extend well down into the water, so that motion is acceptable in waves. Typical overall B/L ratios might now be down around 0.4, becoming even less as boat design gets bigger, provided the center of gravity is kept low.

Of course, this is a simplification of things as top weight, windage, wing clearance, center of gravity, sail plan, etc etc .. all have their effects, though individually less than the important L/B ratio.

Given the dwindling armamentarium for treating MRSP, alternative treatment modalities that can be used safely in the canine population without compromising the efficacy of agents reserved for human infections are desperately needed. As infections predominantly involve the SST, potential therapies include honey-based gels [58] and bacteriophages [59,60]. Additional areas of investigation involve repurposing antimicrobials (e.g., fosmidomycin) [61], and appropriation of nonantimicrobial agents has also garnered interest. For example, carprofen, a nonsteroidal anti-inflammatory drug, appears to restore doxycycline susceptibility in MRSP isolates carrying tetK, while chemotherapeutic agents commonly used in veterinary oncology (e.g., bleomycin) can inhibit S. pseudintermedius growth [62,63]. Finally, candidate components for a vaccine have been proposed and include S. pseudintermedius toxins and virulence factors: Luk-I, protein A, and SpEX [64–66].

If the beam is decreased, stability drops quickly and one may start to also add wave interference between the hulls unless the boat is very light with slim hulls.

If you enter say L = 17 , it will give you a B/L ratio of 0.816, closely matching a W17, while for an L of 100ft, it will give you a B/L of only 0.562, closely matching a big ocean racing tri like Sodeb’O.

If the beam is excessively increased, pitching and reduced diagonal stability (see dwg) start to become an issue and when such boats are lengthened to make their L/B slightly above 2, they generally become faster and have less negative issues ... but over about 2.3, their relatively lower transverse stability then starts to kick back.

The invasive potential of S. pseudintermedius in humans has been demonstrated in several case reports/series of bacteremia, endocarditis, and device-associated infections [19,23,24]. In a striking case report, Darlow and colleagues presented a case of invasive spinal infection in a patient with hardware who had chronic open skin lesions that served as the portal of entry for the organism associated with the patient’s dog. Ensuing bacteremia likely infected the spinal fixation devices in place from a prior surgery [24].

Shipbeam anddraft

While this may initially look complex to calculate for some, it’s very easy with the right help. Download the Mobi Calculator on your phone or tablet. You can then add the expression xn to your basic calculator by first hitting the 3 dots [ ... ] that brings you to the Scientific Options, and then clicking on [ xn ] that will add this feature to your basic calculator. You can now enter the formula exactly as written, typing 1.48 ÷ ( your L value, and then xn and finally 0.21 and the closing bracket ) and then ‘ = ‘.

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But it IS an example of thinking WAY outside the box .. even if the result is not for everyone. So ‘sweetspot L/B ratios’ do not necessarily mean they give the only solution .. just that you, as a designer, also need to work differently around the rest of the design to solve the issues you might create if you are well outside the norm.