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RIVM rapport:Infecties aan maag en darmen, zogeheten enterale infecties, worden veroorzaakt door verschillende bacteriën, parasieten of virussen. Meestal krijgen mensen daarvan maag-darmklachten, zoals overgeven, buikpijn en/of (bloederige) diarree. In sommige gevallen kunnen de klachten ernstig zijn, zoals hepatitis, bloedvergiftiging of hersenvliesontsteking. Mensen raken meestal besmet via voedsel of water dat in contact is gekomen met ontlasting van mensen of dieren. Als de ziekteverwekker via dieren wordt overgedragen, spreken we van zoönosen. Goede hygiëne in toiletten en keukens en bij de bereiding van vlees is heel belangrijk om een besmetting te voorkomen. In 2022 was het aantal mensen met maag-darminfecties veel lager door de coronapandemie, in 2023 was dat effect bijna niet meer te zien. Het aantal infecties was vergelijkbaar met de jaren voor de pandemie. Wel viel in 2023 het hoge aantal infecties op met Shigella, Shiga toxine-producerende E. coli (STEC), norovirus en Cryptosporidium. De stijging van shigellose is vooral te zien onder mannen die seks hebben met mannen (MSM). Voor de andere ziekteverwekkers is geen duidelijke oorzaak bekend. In 2023 is bij verschillende uitbraken onderzocht welke bron de oorzaak was: een uitbraak door de Campylobacter-bacterie, vier uitbraken door de Salmonella-bacterie en één door de STEC-bacterie. Alleen van twee salmonellose-uitbraken is de bron gevonden. Dat waren eieren van leghenbedrijven die besmet waren via besmet voer; en droge worst die niet genoeg was gerijpt. Ook geleedpotigen, zoals muggen en teken, kunnen bacteriën, parasieten en virussen bij zich dragen waar mensen ziek van worden. Hersen(vlies)infecties door het tekenencefalitisvirus zijn in 2023 in drie nieuwe gebieden in Nederland vastgesteld. Tot slot liepen dat jaar een recordaantal reizigers een dengue (knokkelkoorts) infectie op. Deze toename is in de hele wereld te zien. Het RIVM houdt bij hoe vaak dit soort infecties in Nederland voorkomen en brengt uitbraken i, Gastrointestinal, or enteric, infections are caused by various bacterial, parasitic and viral pathogens. Infected people usually experience gastrointestinal complaints, such as vomiting, abdominal pain and/or diarrhoea (which may be bloody). In some cases, serious complaints may develop, such as hepatitis, blood poisoning or meningitis. People usually become infected through food or water that has come into contact with human or animal faeces. When transmitted via animals, we speak of zoonoses. Good hygiene in toilets and kitchens and when preparing meat is very important to prevent infection. In 2022, the number of people with gastrointestinal infections was much lower due to the coronavirus pandemic, in 2023, this effect was almost no longer visible. The number of infections was comparable to the years before the pandemic. However, a notable factor in 2023 was the high number of infections with Shigella, Shiga toxin-producing E. coli (STEC), the norovirus, Cryptosporidium and leptospirosis. The increase in shigellosis was mainly seen among men who have sex with men (MSM). No clear cause is known for the other pathogens. In 2023, an active outbreak investigation was conducted into an outbreak of campylobacteriosis, four salmonellosis outbreaks and a STEC outbreak. The source of only two salmonellosis outbreaks was found. These were eggs from laying hen farms that had been contaminated via contaminated feed; and dry sausage that had insufficiently matured. Arthropods, such as mosquitoes and ticks, can also carry bacteria, parasites and viruses that make people ill. Tickborne encephalitis infections were diagnosed in three new areas in the Netherlands in 2023. Finally, there were a record number of travellers with a dengue infection in 2023. This increase was seen all over the world. RIVM keeps track of how often these types of infections occur in the Netherlands and maps outbreaks. An outbreak is when two or more people are infected by the same source. RIVM then tri

Infecties aan maag en darmen, zogeheten enterale infecties, worden veroorzaakt door verschillende bacteriën, parasieten of virussen. Meestal krijgen mensen daarvan maag-darmklachten, zoals overgeven, buikpijn en/of (bloederige) diarree. In sommige gevallen kunnen de klachten ernstig zijn, zoals hepatitis, bloedvergiftiging of hersenvliesontsteking. In 2023 is bij verschillende uitbraken onderzocht welke bron de oorzaak was: een uitbraak door de Campylobacter-bacterie, vier uitbraken door de Salmonella-bacterie en één door de STEC-bacterie. Alleen van twee salmonellose-uitbraken is de bron gevonden. Dat waren eieren van leghenbedrijven die besmet waren via besmet voer; en droge worst die niet genoeg was gerijpt.

Extra-intestinale infecties zijn infecties die buiten de darmen ontstaan, vooral in urinewegen en de bloedbaan. Er zijn steeds meer aanwijzingen dat extra-intestinale infecties door voedsel kunnen worden veroorzaakt. Een infectie kan dan ontstaan doordat bacteriën uit de ontlasting in de urinewegen terechtkomen. Het RIVM zocht daarom in de wetenschappelijke literatuur of er een verband is. Daar zijn aanwijzingen voor, maar er is geen hard bewijs dat voedsel een directe oorzaak van deze infecties is. Voor dit onderzoek heeft het RIVM eerst gekeken welke ziekteverwekkers in Nederland het vaakst urineweginfecties en bloedbaaninfecties veroorzaken. De extra-intestinale pathogene E. coli (ExPEC) bacterie blijkt de belangrijkste ziekteverwekker te zijn van deze twee soorten infecties. In de wetenschappelijke literatuur is daarom vooral gezocht naar een verband tussen infecties door deze bacterie en voedsel. Het blijkt moeilijk te zijn om aan te tonen of bacteriën die urineweginfecties veroorzaken, uit voedsel komen. Daarvoor moet worden gekeken of de bacteriestam bij de mens hetzelfde is als in voedsel of landbouwdieren. Daarna moet worden onderzocht of mensen daadwerkelijk dit voedselproduct hebben gegeten voordat ze een extraintestinale infectie kregen. Het kost veel tijd en geld om dit soort onderzoek te doen.

The electrical conductance G of magnetostrictive nanocontacts made from Galfenol (Fe73Ga27) can be reproducibly switched between "on" and "off" states in a low magnetic field of similar to 20-30 mT at 10 K. The switching behavior is in agreement with the magnetic field dependence of the magnetostriction inferred from the magnetization behavior, causing a positive magnetostrictive strain along the magnetic field. The repeated magnetic-field cycling leads to a stable contact geometry and to a robust contact configuration with a very low hysteresis of similar to 1 mT between opening and closing the contact due to a training effect. Non-integral multiples of the conductance quantum G(0) observed for G > G(0) are attributed to electron backscattering at defect sites in the electrodes near the contact interface. When the contact is closed either mechanically or by magnetic field, the conductance shows an exponential behavior below G(0) due to electron tunneling. This allows to estimate the magnetostriction lambda = 4 x 10(-5) at 10 K. The results demonstrate that such magnetostrictive devices are suitable for the remote control of the conductance by low magnetic fields in future nanotechnology applications.

The remote control of the electrical conductance through nanosized junctions at room temperature will play an important role in future nano-electromechanical systems and electronic devices. This can be achieved by exploiting the magnetostriction effects of ferromagnetic materials. Here we report on the electrical conductance of magnetic nanocontacts obtained from wires of the giant magnetostrictive compound Tb0.3Dy0.7Fe1.95 as an active element in a mechanically controlled break-junction device. The nanocontacts are reproducibly switched at room temperature between “open” (zero conductance) and “closed” (nonzero conductance) states by variation of a magnetic field applied perpendicularly to the long wire axis. Conductance measurements in a magnetic field oriented parallel to the long wire axis exhibit a different behaviour where the conductance switches between both states only in a limited field range close to the coercive field. Investigating the conductance in the regime of electron tunneling by mechanical or magnetostrictive control of the electrode separation enables an estimation of the magnetostriction. The present results pave the way to utilize the material in devices based on nano-electromechanical systems operating at room temperature.

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Udgivelsesdato: 2007

Udgivelsesdato: 2008

Applied Sciences

It has been proposed that the lac revertants arising under selective conditions in the Cairns experiment do not arise by stress-induced mutagenesis of stationary phase cells as has been previously assumed. Instead, these revertants may arise within growing clones initiated by cells with a preexisting duplication of the weakly functional lac allele used in this experiment. It is proposed that spontaneous stepwise increases in lac copy number (amplification) allow a progressive improvement in growth. Reversion is made more likely primarily by the resultant increase in the number of mutational targets--more cells with more lac copies. The gene amplification model requires no stress-induced variation in the rate or target specificity of mutation and thus does not violate neo-Darwinian theory. However, it does require that a multistep process of amplification, reversion, and amplification segregation be completed within approximately 20 generations of growth. This work examines the proposed amplification model from a theoretical point of view, formalizing it into a mathematical framework and using this to determine what would be required for the process to occur within the specified period. The analysis assumes no stress-induced change in mutation rate and describes only the growth improvement occurring during the process of amplification and subsequent elimination of excess mutant lac copies. The dynamics of the system are described using Monte Carlo simulations and numerical integration of the deterministic equations governing the system. The results imply that the amplification model can account for the behavior of the system using biologically reasonable parameter values and thus can, in principle, explain Cairnsian adaptive mutation.

The objective of this study was to compare growth and carcass traits of 1,252 progeny of six commercially available dam lines included in the National Pork Producers Council Maternal Line Evaluation Project. Lines compared included one maternal line supplied by each of American Diamond Swine Genetics (ADSG), Danbred NA (DB), two lines supplied by Monsanto Choice Genetics (DK and GPK347), Newsham Hybrids (NH), and Landrace × Large White females supplied by the National Swine Registry (NSR). All females were mated to DB, Duroc-Hampshire terminal sires. Traits analyzed were ADG from 56 to 115 kg live weight, days to 115 kg, backfat thickness measured at the 10th rib, carcass length, dressing percent, and 10thrib LM area. Carcass traits were adjusted to a carcass weight of 85 kg. The statistical model included fixed effects of maternal line, sex, farrowing group, and finishing unit (farm). All two-way interactions among main effects were tested and removed from final models because they were not significant. In addition, because they were not significant, effects of farm and farrowing group were removed from models for carcass length and 10th-rib backfat thickness, and farm was removed from the model for LM area. Least squares means for ADG ranged from 0.74 to 0.79 kg/d. The GPK347 line had lower ADG and greater days to 115 kg than all other lines (P < 0.05). The ADSG (P < 0.05) and NH (P < 0.01) progeny had lower ADG than DK progeny. The DK line had the fewest days to 115 kg (P < 0.05). Progeny for the DB and NH lines had the least 10th-rib backfat, differing from ADSG, DK, and GPK347 (P < 0.05). Pigs from DB females had the greatest dressing percent, differing from ADSG, DK, GPK347, and NH (P < 0.05). The GPK347 had a lower dressing percent than all other lines (P < 0.05). Progeny of DB females had the greatest LM area, differing from ADSG, DK, GPK347, and NSR (P < 0.05). Offspring from ADSG and GPK347 had the smallest LM area; however, GPK347 and NSR did not differ.

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The ACE‐2 HILLCLOUD experiment was carried out on the island of Tenerife in June–July 1997 to investigate the interaction of the boundary layer aerosol with a hill cap cloud forming over a ridge to the north‐east of the island. The cloud was used as a natural flow through reactor to investigate the dependence of the cloud microphysics and chemistry on the characteristics of the aerosols and trace gases entering cloud, and to simultaneously study the influence of the physical and chemical processes occurring within the cloud on the size distribution, chemical and hygroscopic properties of the aerosol exiting cloud. 5 major ground base sites were used, measuring trace gases and aerosols upwind and downwind of the cloud, and cloud microphysics and chemistry and interstitial aerosol and gases within the cloud on the hill. 8 intensive measurement periods or runs were undertaken during cloud events, (nocturnally for seven of the eight runs) and were carried out in a wide range of airmass conditions from clean maritime to polluted continental. Polluted air was characterised by higher than average concentrations of ozone (>50 ppbv), fine and accumulation mode aerosols (>3000 and >1500 cm−3, respectively) and higher aerosol mass loadings. Cloud droplet number concentrations N, increased from 50 cm−3 in background maritime air to >2500 cm−3 in aged polluted continental air, a concentration much higher than had previously been detected. Surprisingly, N was seen to vary almost linearly with aerosol number across this range. The droplet aerosol analyser (DAA) measured higher droplet numbers than the corrected forward scattering spectrometer probe (FSSP) in the most polluted air, but at other times there was good agreement (FSSP=0.95 DAA with an r2=0.89 for N<1200 cm−3). Background ammonia gas concentrations were around 0.3 ppbv even in air originating over the ocean, another unexpected but important result for the region. NO2 was present in background concentrations of typically

Most types of antibiotic resistance impose a biological cost on bacterial fitness. These costs can be compensated, usually without loss of resistance, by second-site mutations during the evolution of the resistant bacteria in an experimental host or in a laboratory medium. Different fitness-compensating mutations were selected depending on whether the bacteria evolved through serial passage in mice or in a laboratory medium. This difference in mutation spectra was caused by either a growth condition-specific formation or selection of the compensated mutants. These results suggest that bacterial evolution to reduce the costs of antibiotic resistance can take different trajectories within and outside a host.

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