Complex systems are always correlated but rarely information processing

`Complex systems are information processors' is a statement that is frequently made. Here we argue for the distinction between information processing -- in the sense of encoding and transmitting a symbolic representation -- and the formation of correlations (pattern formation / self-organisation). The study of both uses tools from information theory, but the purpose is very different in each case: explaining the mechanisms and understanding the purpose or function in the first case, versus data analysis and correlation extraction in the latter. We give examples of both and discuss some open questions. The distinction helps focus research efforts on the relevant questions in each case.

Intravenous Immunoglobulin (IVIG) in Treating Non-ventilated COVID-19 Patients with Moderate to Severe Hypoxia is Pharmacoeconomically Favorable When Appropriately Targeted

Background: Prior studies have shown that intravenous immunoglobulin (IVIG) can improve outcomes in patients with COVID-19, but the high costs of IVIG leave questions as to its pharmacoeconomic value. Methods: The hospital costs of 2 IVIG vs. non-IVIG COVID-19 patient groups were compared. The first cohort was a case-control analysis of 10 non-ventilated moderately to severely hypoxic COVID-19 patients who received IVIG (Privigen) matched 1:2 with 20 control patients of similar age, body mass index (BMI), degree of hypoxemia, and co-morbidities. The second cohort consisted of patients enrolled in a previously published randomized open-label prospective study of 14 COVID-19 patients receiving standard of care (SOC) versus 13 patients who received SOC plus IVIG (Octagam 10%). Results: Among the first case control population, mean total direct costs including IVIG for the treatment group was $21,982 per IVIG-treated case versus $42,431 per case for matched non-IVIG receiving controls, representing a net cost reduction of $20,449 (48%) per case. For the second (randomized) group, mean total direct costs including IVIG for the treatment group was $28,268 per case versus $62,707 per case for untreated controls, representing a net cost reduction of $34,439 (55%) per case. 24% of the non-IVIG patients had hospital costs exceeded $80,000, as compared to none of the IVIG patient host (p=0.016, Fisher exact test). Conclusion: When allocated to the appropriate patient type (moderate to severe illness without end-organ comorbidities and age <70 years), IVIG can significantly reduce hospital costs in COVID-19 care. More importantly, it may reduce the demand on scare critical care resources during the COVID-19 pandemic.

Refining the Rib-sparing Approach in Microsurgical Breast Reconstruction: Keys to Success

Background Free tissue transfer using microsurgical techniques is a popular option for breast reconstruction, and the internal mammary vessels remain the most popular recipient vessels for the anastomosis. Traditionally, ribs were resected for better access to these vessels in the intercostal space. However, rib resection has the potential for complications and adds a surgical step. Here, the authors evaluate and compare both techniques in a retrospective study as well as offer technical pearls. Methods The 400 most recent consecutive patients who underwent microsurgical breast reconstruction by a single surgeon were retrospectively reviewed. 54 patients underwent the traditional rib-resecting approach. 346 patients underwent the rib-sparing approach, which was the preferred approach of the senior author, when possible. Patients requiring the rib-resecting approach were distributed evenly throughout the series. Primary outcomes were any immediate post-operative complications. Results Between the two clinical groups, there was no difference between demographic or clinical details, the flap type, history of previous radiation, or timing of reconstruction. Complications of any kind as well as the subset of complications were significantly more frequent in the rib resection than in the rib-sparing group. Specifically, the rate of reanastomosis was higher in the rib resection group [10.6 vs 2.7%, p < 0.001] as was the frequency of return to the OR in the immediate post-operative setting [3.0 vs 0.3%, p < 0.001]. There is a 4.50 odds ratio of having a complication in a rib resection case versus rib sparing [CI: 1.97–10.30, p < 0.001]. All cases were initiated with the intent to perform a rib-sparing approach if possible, and they were converted to a rib-resection approach as needed. Conclusion In the largest reported series to date, the rib-sparing approach is demonstrated to be both safe and efficacious in microsurgical breast reconstruction.

Mobile outreach testing for COVID-19 in twenty homeless shelters in Toronto, Canada

BackgroundIt is unclear what the best strategy is for detecting COVID-19 among homeless shelter residents and what individual factors are associated with positivity.MethodsWe conducted a retrospective chart audit obtaining repeated cross-sectional data from outreach testing done at homeless shelters between April 1st and July 31st, 2020 in Toronto, Canada. We compared the positivity rate for shelters tested because of an outbreak (at least one known case) versus surveillance (no known cases). A patient-level analysis examined differences in demographic, health, and behavioural characteristics of residents who did and did not test positive for COVID-19.FindingsOne thousand nasopharyngeal swabs were done on 872 unique residents at 20 shelter locations. Among the 504 tests done in outbreak settings, 69 (14%) were positive and 1 (0.2%) was indeterminate. Among the 496 tests done for surveillance, 11 (2%) were positive and none were indeterminate. Shelter residents who tested positive were significantly less likely to have a health insurance card (54% vs 72%, p=0.03) or have visited another shelter in the last 14 days (0% vs 18%, p<0.01) compared to those who tested negative; There was no association between COVID-19 positivity and medical history (p=0.40) or symptoms (p=0.43).InterpretationOur findings support testing of asymptomatic shelter residents for COVID-19 when a positive case is identified at the same shelter but suggest limited utility of testing all shelter residents in the absence of a known case. Visiting another shelter in the last 14 days is associated with a decreased risk of COVID-19 positivity.

Deadly injuries through recoilless anti-tank weapons while military shooting practice—two case studies from Germany and Switzerland

In this casuistry, two accidents from Germany and Switzerland are presented that happened during the shot of recoilless anti-tank weapons. In both cases, the injuries led to the death of two soldiers: A 22-year-old soldier in Germany was struck by the counter mass of a so-called Davis gun which had been fired by a comrade during a firing exercise; he died from his severe injuries, especially in the abdominal part of the body. As a peculiarity of the wound morphology, it was found to be a thick-layered, metallic, gray material in the wound cavity, which corresponded to the material of the counter mass that was ejected opposite to the shooting direction. The other case took place in Switzerland, where a 24-year-old soldier was seriously injured during an exercise with portable anti-tank rockets. At the time the shot was fired, he stood behind the launcher and was hit by the propulsion jet of the rocket motor. He died as well from his severe injuries, which were located at the chest done by the gas jet and by the very high pressure. In both cases, two different causes of death were present: massive blunt violence in the first case versus a jet of hot gases of very high speed and temperature in the second case.