Stationary non equilibrium solutions to the Boltzmann equation, despite their relevance in applications, are much less studied than time dependent solutions, and no general existence theory is yet ...available, due to serious technical difficulties. Here we review some results on the construction of stationary non equilibrium solutions, in a general domain in contact with a slightly non-homogeneous thermal reservoir, both for finite and small Knudsen number. We will describe different approaches and different techniques developed. The main focus will be on stationary solutions close to hydrodynamics. In particular, we will give an answer to the longstanding open problem of the rigorous derivation of the steady incompressible Navier–Stokes–Fourier system from the Boltzmann theory, in the presence of a small external force and diffuse boundary condition with small boundary temperature variations.
Given an obstacle in
R
3
and a non-zero velocity with small amplitude at the infinity, we construct the unique steady Boltzmann solution flowing around such an obstacle with the prescribed velocity ...as
|
x
|
→
∞
, which approaches the corresponding Navier–Stokes steady flow, as the mean-free path goes to zero. Furthermore, we establish the error estimate between the Boltzmann solution and its Navier–Stokes approximation. Our method consists of new
L
6
and
L
3
estimates in the unbounded exterior domain, as well as an iterative scheme preserving the positivity of the distribution function.
In the study of the heat transfer in the Boltzmann theory, the basic problem is to construct solutions to the following steady problem:
v
·
∇
x
F
=
1
K
n
Q
(
F
,
F
)
,
(
x
,
v
)
∈
Ω
×
R
3
,
(
0.1
)
F
...(
x
,
v
)
|
n
(
x
)
·
v
<
0
=
μ
θ
∫
n
(
x
)
·
v
′
>
0
F
(
x
,
v
′
)
(
n
(
x
)
·
v
′
)
d
v
′
,
x
∈
∂
Ω
,
(
0.2
)
where
Ω
is a bounded domain in
R
d
,
1
≤
d
≤
3
, K
n
is the Knudsen number and
μ
θ
=
1
2
π
θ
2
(
x
)
exp
-
|
v
|
2
2
θ
(
x
)
is a Maxwellian with non-constant(non-isothermal) wall temperature
θ
(
x
). Based on new constructive coercivity estimates for both steady and dynamic cases, for
|
θ
-
θ
0
|
≤
δ
≪
1
and any fixed value of K
n
, we construct a unique non-negative solution
F
s
to (0.1) and (0.2), continuous away from the grazing set and exponentially asymptotically stable. This solution is a genuine non-equilibrium stationary solution differing from a local equilibrium Maxwellian. As an application of our results we establish the expansion
F
s
=
μ
θ
0
+
δ
F
1
+
O
(
δ
2
)
and we prove that, if the Fourier law holds, the temperature contribution associated to
F
1
must be linear, in the slab geometry.
•We performed a systematic review and meta-analysis of 33 observational studies.•All COVID-19 vaccine studies compared immunocompromised patients vs. control group.•Outcome suggests the effectiveness ...of COVID-19 mRNA vaccines.•Serological response was significantly high in the control group.
We aimed to assess the short-term effectiveness of COVID-19 vaccines among immunocompromised patients to prevent laboratory-confirmed symptomatic COVID-19 infection.
Systematic review and meta-analysis. We calculated the pooled diagnostic odds ratio DOR (95% CI) for COVID-19 infection between immunocompromised patients and healthy people or those with stable chronic medical conditions. VE was estimated as 100% x (1-DOR). We also investigated the rates of developing anti-SARS-CoV-2 spike protein IgG between the 2 groups.
Twenty studies evaluating COVID-19 vaccine response, and four studies evaluating VE were included in the meta-analysis. The pooled DOR for symptomatic COVID-19 infection in immunocompromised patients was 0.296 (95% CI: 0.108–0.811) with an estimated VE of 70.4% (95% CI: 18.9%- 89.2%). When stratified by diagnosis, IgG antibody levels were much higher in the control group compared to immunocompromised patients with solid organ transplant (pOR 232.3; 95% Cl: 66.98–806.03), malignant diseases (pOR 42.0, 95% Cl: 11.68–151.03), and inflammatory rheumatic diseases (pOR 19.06; 95% Cl: 5.00–72.62).
We found COVID-19 mRNA vaccines were effective against symptomatic COVID-19 among the immunocompromised patients but had lower VE compared to the controls. Further research is needed to understand the discordance between antibody production and protection against symptomatic COVID-19 infection.
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Clostridioides difficile infection is an increasing presence worldwide. Prevention is multipronged, reflecting a complex and evolving epidemiology. Multiple guidelines exist regarding the prevention ...of C. difficile infection in healthcare settings; however, existing guidelines do not address C. difficile in low- and middle-income countries (LMIC). Nevertheless, the prevalence of C. difficile in LMIC likely parallels, if not exceeds, that of high-income countries, and LMIC may experience additional challenges in C. difficile diagnosis and control. A panel of experts was convened by the International Society for Infectious Diseases (ISID) to review the current state of C. difficile infections globally and make evidence-based recommendations for infection prevention that are broadly applicable.
•Vietnam’s urban poor disproportionately live in smaller cities.•Small cities lag behind in access to basic services such as piped drinking water.•Inequality in the five largest cities is low; ...between 0.07 (DaNang) and 0.144 (HCM) measured with the Theil L indicator.•Except for Can Tho, between-district inequality is also low (less than 20%) in the five largest cities.•Households in larger cities have lower subjective welfare as measured by self-reported food sufficiency.
Vietnam’s urban population is growing rapidly: by 2020 45% of Vietnamese are forecasted to be residing in cities. Even though poverty today remains predominantly a rural phenomenon, there is a need to better understand the landscape of poverty in urban areas. Drawing on small-area estimation methods we estimate welfare outcomes at the level of individual towns and cities in Vietnam, including even the smallest towns. Such estimates could not be produced using national sample surveys alone. Results show an inverse relationship between poverty and city size in Vietnam, with the urban poor being disproportionately concentrated in small towns and cities. This relationship is robust to the location of the poverty line as well as to alternative city-size definitions. Interestingly, our evidence of a clear gradient between absolute poverty and city size is not replicated for subjective welfare, measured by self-reported food sufficiency. The absolute poverty-city size gradient does, however, accord with the observation of striking variation in service availability across cities of different size in Vietnam. Small town residents are typically confronted with far lower per-capita availability of basic services than are large city dwellers. The results suggest that policymakers concerned to tackle urban poverty in Vietnam should not neglect attending to smaller towns. Addressing inequalities in access to key basic services across the entire urban population may represent one means to this end.
•Increasingly, hospitals are discontinuing contact precautions for patients colonized and infected with methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci ...(VRE).•This systematic review and meta-analysis showed that discontinuing contact precautions for endemic MRSA and VRE was not associated with an increase in infection rates.•The utility of contact precautions for controlling MRSA and VRE is probably low.
Several single-center studies have suggested that eliminating contact precautions (CPs) for methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) control in nonoutbreak settings has no impact on infection rates. We performed a systematic literature review and meta-analysis on the impact of discontinuing contact precautions in the acute care setting.
We searched PubMed, CINAHL, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, and Embase through December 2016 for studies evaluating discontinuation of contact precautions for multidrug-resistant organisms. We used random-effect models to obtain pooled risk ratio estimates. Heterogeneity was evaluated with I2 estimation and the Cochran Q statistic. Pooled risk ratios for MRSA and VRE were assessed separately.
Fourteen studies met inclusion criteria and were included in the final review. Six studies discontinued CPs for both MRSA and VRE, 3 for MRSA only, 2 for VRE only, 2 for extended-spectrum β-lactamase–producing Escherichia coli, and 1 for Clostridium difficile infection. When study results were pooled, there was a trend toward reduction of MRSA infection after discontinuing CPs (pooled risk ratio, 0.84; 95% confidence interval, 0.70-1.02; P = .07) and a statistically significant reduction in VRE infection (pooled risk ratio, 0.82; 95% confidence interval, 0.72-0.94; P = .005).
Discontinuation of CPs for MRSA and VRE has not been associated with increased infection rates.
Of the 2,668 patients admitted with coronavirus disease 2019 (COVID-19), 4% underwent prolonged isolation for >20 days. Reasons for extended isolation were inconsistent with Centers for Disease ...Control and Prevention (CDC) guidelines in 25% of these patients and were questionable in 54% due to an ongoing critically ill condition at day 20 without CDC-defined immunocompromised status.
There is ample literature available on the association between both time to antibiotics and appropriateness of antibiotics and clinical outcomes from sepsis. In fact, the current state of debate ...surrounds the balance to be struck between prompt empirical therapy and care in the choice of appropriate antibiotics (both in terms of the susceptibility of infecting organism and minimizing resistance arising from use of broad-spectrum agents). The objective of this study is to determine sepsis bundle compliance and the appropriateness of antimicrobial therapy in patients with severe sepsis and septic shock and its impact on outcomes.
This study was conducted in the ICU of a tertiary care, private hospital in São Paulo, Brazil. A retrospective cohort study was conducted from July 2005 to December 2012 in patients with severe sepsis and septic shock.
A total of 1,279 patients were identified with severe sepsis and septic shock, of which 358 (32.1%) had bloodstream infection (BSI). The inpatient mortality rate was 29%. In evaluation of the sepsis bundle, over time there was a progressive increase in serum arterial lactate collection, obtaining blood cultures prior to antibiotic administration, administration of broad-spectrum antibiotics within 1 hour, and administration of appropriate antimicrobials, with statistically significant differences in the later years of the study. We also observed a significant decrease in mortality. In patients with bloodstream infection, after adjustment for other covariates the administration of appropriate antimicrobial therapy was associated with a decrease in mortality in patients with severe sepsis and septic shock (p = 0.023).
The administration of appropriate antimicrobial therapy was independently associated with a decline in mortality in patients with severe sepsis and septic shock due to bloodstream infection. As protocol adherence increased over time, the crude mortality rate decreased, which reinforces the need to implement institutional guidelines and monitor appropriate antimicrobial therapy compliance.
Stenotrophomonas maltophilia is a bacteria whose role in patients with cystic fibrosis bronchiectasis has been previously studied; little is known about its role in non-CF bronchiectasis.
Investigate ...the risk factors for S. Maltophilia acquisition and its clinical impact on bronchiectasis patients.
A retrospective observational cohort study enrolling patients attending the Bronchiectasis Clinic at the Royal Infirmary of Edinburgh, Scotland, UK.
167 bronchiectasis patients undergoing intravenous antibiotic therapy were selected and divided according to single or chronic S. Maltophilia isolation in sputum. The risk factors and prognostic impact was studied.
Single isolation was independently associated with lower baseline % predicted FEV1 (OR 0.98; 95%CI 0.970-1,044; p = 0.025) and with less radiological involvement (OR 0.379; 95%CI 0.175-0.819; p = 0.01). Chronic isolation was associated with the number of intravenous antibiotic courses in the year before and after the first isolation (OR 1.2; 95%CI 1.053-1.398; p = 0.007) and with the absence of P. Aeruginosa colonisation (OR 0.207; 95%CI 0.056-0.764; p = 0.02). In the chronic isolation group, there were more exacerbations and more need of intravenous antibiotics in the year after the first isolation.
Poor lung function is the main independent risk factor for single isolation of S. maltophilia. For chronic colonisation, the main independent risk factor is the number of intravenous antibiotic courses and the absence of P. aeruginosa chronic colonisation. Only when chronically present, S. maltophilia had a clinical impact with more exacerbations.
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