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"Jacobson, Peter"
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Disentangling the effects of a century of eutrophication and climate warming on freshwater lake fish assemblages
by
Hansen, Gretchen J. A.
,
Cross, Timothy K.
,
Jacobson, Peter C.
in
Abundance
,
Animals
,
Aquatic ecosystems
2017
Eutrophication and climate warming are profoundly affecting fish in many freshwater lakes. Understanding the specific effects of these stressors is critical for development of effective adaptation and remediation strategies for conserving fish populations in a changing environment. Ecological niche models that incorporated the individual effects of nutrient concentration and climate were developed for 25 species of fish sampled in standard gillnet surveys from 1,577 Minnesota lakes. Lake phosphorus concentrations and climates were hindcasted to a pre-disturbance period of 1896-1925 using existing land use models and historical temperature data. Then historical fish assemblages were reconstructed using the ecological niche models. Substantial changes were noted when reconstructed fish assemblages were compared to those from the contemporary period (1981-2010). Disentangling the sometimes opposing, sometimes compounding, effects of eutrophication and climate warming was critical for understanding changes in fish assemblages. Reconstructed abundances of eutrophication-tolerant, warmwater taxa increased in prairie lakes that experienced significant eutrophication and climate warming. Eutrophication-intolerant, warmwater taxa abundance increased in forest lakes where primarily climate warming was the stressor. Coolwater fish declined in abundance in both ecoregions. Large changes in modeled abundance occurred when the effects of both climate and eutrophication operated in the same direction for some species. Conversely, the effects of climate warming and eutrophication operated in opposing directions for other species and dampened net changes in abundance. Quantifying the specific effects of climate and eutrophication will allow water resource managers to better understand how lakes have changed and provide expectations for sustainable fish assemblages in the future.
Journal Article
Life Expectancy after Bariatric Surgery in the Swedish Obese Subjects Study
by
Jacobson, Peter
,
Andersson-Assarsson, Johanna C
,
Carlsson, Björn
in
Adult
,
Bariatric Surgery
,
Bariatric Surgery - mortality
2020
This study compared long-term mortality and life expectancy among patients who underwent bariatric surgery or received usual obesity care in the Swedish Obese Subjects study and in persons in the SOS reference study. The adjusted median life expectancy with surgery was 3.0 years longer than in control patients but 5.5 years shorter than in the general population.
Journal Article
Examining Whether The Health-In-All-Policies Approach Promotes Health Equity
2018
Scholars and public health advocates have expressed optimism about the potential for the health-in-all-policies approach to address social disparities in health, but little research has been done on whether it promotes health equity in practice. Based on sixty-five in-depth interviews with US officials in the public and private sectors conducted in five states in 2016-17, we found a relationship between the use of the approach and the prominence of health equity as a policy concern. In emphasizing the social determinants of health, the approach gives public officials and policy entrepreneurs a framework for promoting this goal. In some areas, we found a gradual transition in focus from health generally to health equity. Overall, we found that practitioners of the approach introduce equity selectively and strategically.
Journal Article
Effects of bariatric surgery on cancer incidence in obese patients in Sweden (Swedish Obese Subjects Study): a prospective, controlled intervention trial
2009
Obesity is a risk factor for cancer. Intentional weight loss in the obese might protect against malignancy, but evidence is limited. To our knowledge, the Swedish Obese Subjects (SOS) study is the first intervention trial in the obese population to provide prospective, controlled cancer-incidence data.
The SOS study started in 1987 and involved 2010 obese patients (body-mass index [BMI] ≥34 kg/m
2 in men, and ≥38 kg/m
2 in women) who underwent bariatric surgery and 2037 contemporaneously matched obese controls, who received conventional treatment. While the main endpoint of SOS was overall mortality, the main outcome of this exploratory report was cancer incidence until Dec 31, 2005. Cancer follow-up rate was 99·9% and the median follow-up time was 10·9 years (range 0–18·1 years).
Bariatric surgery resulted in a sustained mean weight reduction of 19·9 kg (SD 15·6 kg) over 10 years, whereas the mean weight change in controls was a gain of 1·3 kg (SD 13·7 kg). The number of first-time cancers after inclusion was lower in the surgery group (n=117) than in the control group (n=169; HR 0·67, 95% CI 0·53–0·85, p=0·0009). The sex–treatment interaction p value was 0·054. In women, the number of first-time cancers after inclusion was lower in the surgery group (n=79) than in the control group (n=130; HR 0·58, 0·44–0·77; p=0·0001), whereas there was no effect of surgery in men (38 in the surgery group
vs 39 in the control group; HR 0·97, 0·62–1·52; p=0·90). Similar results were obtained after exclusion of all cancer cases during the first 3 years of the intervention.
Bariatric surgery was associated with reduced cancer incidence in obese women but not in obese men.
Swedish Research Council, Swedish Foundation for Strategic Research, Swedish Federal Government under the LUA/ALF agreement, Hoffmann La Roche, Cederoths, AstraZeneca, Sanofi-Aventis, Ethicon Endosurgery.
Journal Article
Bariatric Surgery and Prevention of Type 2 Diabetes in Swedish Obese Subjects
by
Bouchard, Claude
,
Jacobson, Peter
,
Näslund, Ingmar
in
Adult
,
Bariatric Surgery
,
Biological and medical sciences
2012
In this report from the Swedish Obese Subjects study, the rate of incident type 2 diabetes in usual-care and bariatric-surgery groups was 28.4 and 6.8 cases per 1000 person-years, respectively. These findings suggest that surgery is much more efficient than usual care.
Multiple studies have shown associations between obesity and type 2 diabetes
1
–
6
and between changes in body weight and incident type 2 diabetes.
7
,
8
It is also well established that the worldwide increase in obesity is associated with an increase in the prevalence of type 2 diabetes.
9
Currently, 285 million people have type 2 diabetes, and this number is predicted to increase to 439 million by 2030.
10
Among persons in a prediabetic state, the incidence of type 2 diabetes is reduced by approximately 40 to 45% with effective lifestyle changes or drug treatment,
11
–
15
and the effects persist, in part, . . .
Journal Article
Quantum engineering of spin and anisotropy in magnetic molecular junctions
by
Jacobson, Peter
,
Herden, Tobias
,
Kern, Klaus
in
639/766/119/1001
,
639/766/119/997
,
639/766/25
2015
Single molecule magnets and single spin centres can be individually addressed when coupled to contacts forming an electrical junction. To control and engineer the magnetism of quantum devices, it is necessary to quantify how the structural and chemical environment of the junction affects the spin centre. Metrics such as coordination number or symmetry provide a simple method to quantify the local environment, but neglect the many-body interactions of an impurity spin coupled to contacts. Here, we utilize a highly corrugated hexagonal boron nitride monolayer to mediate the coupling between a cobalt spin in CoH
x
(
x
=1,2) complexes and the metal contact. While hydrogen controls the total effective spin, the corrugation smoothly tunes the Kondo exchange interaction between the spin and the underlying metal. Using scanning tunnelling microscopy and spectroscopy together with numerical simulations, we quantitatively demonstrate how the Kondo exchange interaction mimics chemical tailoring and changes the magnetic anisotropy.
The spins of single molecules and defect centres possess properties which can be strongly influenced by their material contacts in electrical junctions. Here, the authors study the coupling between cobalt hydride complexes and a Rh(111) contact, mediated through a hexagonal boron nitride layer.
Journal Article
Non-Rainfall Moisture Activates Fungal Decomposition of Surface Litter in the Namib Sand Sea
by
Wenndt, Anthony
,
Jacobson, Kathryn
,
Jacobson, Peter
in
Accounting
,
Animal models
,
Annual rainfall
2015
The hyper-arid western Namib Sand Sea (mean annual rainfall 0-17 mm) is a detritus-based ecosystem in which primary production is driven by large, but infrequent rainfall events. A diverse Namib detritivore community is sustained by minimal moisture inputs from rain and fog. The decomposition of plant material in the Namib Sand Sea (NSS) has long been assumed to be the province of these detritivores, with beetles and termites alone accounting for the majority of litter losses. We have found that a mesophilic Ascomycete community, which responds within minutes to moisture availability, is present on litter of the perennial Namib dune grass Stipagrostis sabulicola. Important fungal traits that allow survival and decomposition in this hyper-arid environment with intense desiccation, temperature and UV radiation stress are darkly-pigmented hyphae, a thermal range that includes the relatively low temperature experienced during fog and dew, and an ability to survive daily thermal and desiccation stress at temperatures as high as 50°C for five hours. While rainfall is very limited in this area, fog and high humidity provide regular periods (≥ 1 hour) of sufficient moisture that can wet substrates and hence allow fungal growth on average every 3 days. Furthermore, these fungi reduce the C/N ratio of the litter by a factor of two and thus detritivores, like the termite Psammotermes allocerus, favor fungal-infected litter parts. Our studies show that despite the hyper-aridity of the NSS, fungi are a key component of energy flow and biogeochemical cycling that should be accounted for in models addressing how the NSS ecosystem will respond to projected climate changes which may alter precipitation, dew and fog regimes.
Journal Article
Correlation-driven transport asymmetries through coupled spins in a tunnel junction
by
Jacobson, Peter
,
Kern, Klaus
,
Ternes, Markus
in
639/301/119/997
,
639/766/119/2793
,
Anisotropy
2017
Spin–spin correlations can be the driving force that favours certain ground states and are key in numerous models that describe the behaviour of strongly correlated materials. While the sum of collective correlations usually lead to a macroscopically measurable change in properties, a direct quantification of correlations in atomic scale systems is difficult. Here we determine the correlations between a strongly hybridized spin impurity on the tip of a scanning tunnelling microscope and its electron bath by varying the coupling to a second spin impurity weakly hybridized to the sample surface. Electronic transport through these coupled spins reveals an asymmetry in the differential conductance reminiscent of spin-polarized transport in a magnetic field. We show that at zero field, this asymmetry can be controlled by the coupling strength and is related to either ferromagnetic or antiferromagnetic spin–spin correlations in the tip.
Spin-spin correlation is fundamental to many material properties but challenging to measure in nanomagnetic systems. Muenks
et al
. show that correlations between a localized spin and the electrons of its hosting bath can be quantified when coupled to another spin by an asymmetry in the differential conductance.
Journal Article
Accounting for non-rainfall moisture and temperature improves litter decay model performance in a fog-dominated dryland system
2022
Historically, ecosystem models have treated rainfall as the primary moisture source driving litter decomposition. In many arid and semi-arid lands, however, non-rainfall moisture (fog, dew, and water vapor) plays a more important role in supporting microbial activity and carbon turnover. To date though, we lack a robust approach for modeling the role of non-rainfall moisture in litter decomposition. We developed a series of simple litter decay models with different moisture sensitivity and temperature sensitivity functions to explicitly represent the role of non-rainfall moisture in the litter decay process. To evaluate model performance, we conducted a 30-month litter decomposition study at 6 sites along a fog and dew gradient in the Namib desert, spanning almost an eightfold difference in non-rainfall moisture frequency. Litter decay rates in the field correlated with fog and dew frequencies but not with rainfall. Including either temperature or non-rainfall moisture sensitivity functions improved model performance, but the combination of temperature and moisture sensitivity together provided more realistic estimates of litter decomposition than relying on either alone. Model performance was similar regardless of whether we used continuous moisture sensitivity functions based on relative humidity or a simple binary function based on the presence of moisture, although a Gaussian temperature sensitivity outperformed a monotonically increasing Q10 temperature function. We demonstrate that explicitly modeling non-rainfall moisture and temperature together is necessary to accurately capture litter decay dynamics in a fog-affected dryland system and provide suggestions for how to incorporate non-rainfall moisture into existing Earth system models.
Journal Article
Long-term incidence of colorectal cancer after bariatric surgery or usual care in the Swedish Obese Subjects study
by
Jacobson, Peter
,
Carlsson, Lena M. S.
,
Taube, Magdalena
in
Adult
,
adverse effects
,
Alcohol use
2021
Bariatric surgery in patients with obesity is generally considered to reduce cancer risk in patients with obesity. However, for colorectal cancer some studies report an increased risk with bariatric surgery, whereas others report a decreased risk. These conflicting results demonstrate the need of more long-term studies analyzing the effect of bariatric surgery on colorectal cancer risk. Therefore, data from the Swedish Obese Subjects (SOS) study, ClinicalTrials.gov identifier: NCT01479452, was used to examine the impact of bariatric surgery on long-term incidence of colorectal cancer. The SOS study includes 2007 patients who underwent bariatric surgery and 2040 contemporaneously matched controls who received conventional obesity treatment. Patients in the surgery group underwent gastric bypass (n = 266), banding (n = 376) or vertical banded gastroplasty (n = 1365). Information on colorectal cancer events was obtained from the Swedish National Cancer Registry. Median follow-up was 22.2 years (inter-quartile range 18.3–25.2). During follow up there were 58 colorectal cancer events in the surgery group and 67 colorectal cancer events in the matched control group with a hazard ratio (HR) of 0.79 (95% CI:0.55–1.12; p = 0.183). After adjusting for age, body mass index, alcohol intake, smoking status, and diabetes, the adjusted HR was 0.89 (95% CI:0.62–1.29; p = 0.551). When analyzing rectal cancer events separately- 19 events in the surgery group and 31 events in the control group-a decreased risk of rectal cancer with surgery was observed (HR = 0.56; 95% CI:0.32–0.99; p = 0.045, adjusted HR = 0.61 (95% CI:0.34–1.10; p = 0.099), while the risk of colon cancer was unchanged. To conclude- in this long-term, prospective study, bariatric surgery was not associated with altered colorectal cancer risk.
Journal Article