Steam storage systems for flexible biomass CHP plants - Evaluation and initial model based calculation

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Within the present study a novel concept for the demand-oriented power generation of a solid-biomass fueled combined heat and power (CHP) plant is investigated. The integration of a steam storage system into the plants process enables a decoupling of the steam (boiler) and the power generation (steam turbine). By buffering the steam, the power output of the turbine can be adjusted without changing the rated thermal capacity of the plant. Various available storage systems are selected and comparatively evaluated applying the adapted analytic hierarchy process (AHP). The technology assessment revealed that the combination of a steam accumulator and solid concrete storage represents the best suiting option. An initial model based simulation study is performed to identify the fundamental behaviour of this system, integrated in a biomass CHP plant. The operation principle is has proved their technical feasibility and seems to be applicable at a commercial scale. According to the modelling results flexible short term power generation in a time range of up to fifteen minutes is applicable. A load-range of almost the plants rated capacity can be achieved

How to Make People Make a Change – Using Social Labelling for Raising Awareness on Sustainable Manufacturing

Raising awareness on sustainable manufacturing, especially when it comes to low qualified target groups, remains a challenge. After a decade of considerable campaigning work, the majority of German population still does not understand the holistic concept of a sustainable development, let alone its manufacturing aspects. More effective communication methods are required. The main challenge lies within stirring people's willingness to gain knowledge and to actually consider it when making behavioral choices. In the reported research, the socio-psychological concept of social labelling is introduced as a method for raising the awareness on sustainable manufacturing of non-professional target groups and for triggering durable behavioral change. A social label is largely independent from actual knowledge, attitudes or behavior; it rather enforces attributed personal traits. A field experiment, in which the influence of social labelling on the awareness and behavior of young recipients of an informational event has been measured, has verified the method for the purpose of sustainability communication

Duldungsverhalten, Ovulationsverlauf und Konzeptionsergebnisse von Jung- und Altsauen nach Ovulationssynchronisation in verschiedenen Behandlungsvarianten

In der Schweineproduktion stellt die Anwendung biotechnischer Maßnahmen zur Steuerung des Reproduktionsgeschehens ein Mittel zur Verbesserung des betrieblichen Managements und der Produktivität dar. Dabei soll die Nutzung der eingesetzten Hormone möglichst auf ein notwendiges Maß reduziert werden. Ziel der Studie war es, unter Einsatz der transkutanen Sonographie weitere Erkenntnisse über das Duldungsverhalten und den Ovulationsverlauf unter besonderer Berücksichtigung verschiedener Behandlungsvarianten der Ovulations-synchronisation mit terminorientierter Besamung bei Jung- und Altsauen zu gewinnen. Der Befruchtungserfolg in Abhängigkeit von der verwendeten Behandlungsvariante der ovulationssynchronisierten Sauen sollte zusätzlich Rückschlüsse auf das Behandlungsmanagement liefern. Im ersten Teil der Studie wurde das Brunst- und Ovulationsverhalten sowie die Konzeptionsrate von 1742 Jung- und Altsauen zweier Landwirtschaftsbetriebe analysiert. Hierbei wurden die Sauen nach verschiedenen zur Zeit üblichen biotechnischen Behandlungsvarianten der Ovulationssynchronisation mit terminorientierten Besamung behandelt. Die Befunderhebung erfolgte mittels zweimal täglicher Kontrolle der Brunstsymptome zum Zeitpunkt der Inseminationen. Der Ovulationsverlauf sowie die Konzeptionsrate am 30. Trächtigkeitstag wurde durch die Anwendung der transkutanen Sonographie am unbeeinflußten, stehenden Tier bestimmt. Alle Jungsauen des Praxisbetriebes A wurden einer 15tägigen Zyklusblockade durch das Progestagen Altrenogest (Regumate®, Roussel Uclaf) unterzogen. Die Brunst-stimulation erfolgte bei den Jungsauen 24 Stunden nach der letzten Regumate®-Gabe und bei den Altsauen 24 Stunden nach dem Absetzen mittels einer intra-muskulären PMSG-Applikation. Zur Ovulationsinduktion wurde im Praxisbetrieb A einerseits 500 IE hCG (Ekluton® 1500, Vemie Veterinär Chemie) und andererseits 25 µg des GnRH-Analogons D-Phen6-LHRH (Gonavet®, Veyx Pharma GmbH) entsprechend der Behandlungsvariante verabreicht. Das Zeitintervall zwischen den beiden Injektionen betrug bei den Jungsauen 80 Stunden und bei den Altsauen 58 Stunden. Im Betrieb B erfolgte eine Unterteilung der Altsauen in Tiere nach dem 1. Wurf (primipare Sauen, n = 214) und Sauen mit mehr als 2 Würfen (WNr. 3-11), da in diesem Betrieb bei den primiparen Sauen ein modifiziertes biotechnisches Verfahren angewendet wurde. Zur Ovulationsinduktion der Jungsauen und der primiparen Sauen im Praxisbetrieb B wurden 50 µg des GnRH-Analogons Gonavet® eingesetzt. Die Altsauen dieses Betriebes erhielten 25 µg Gonavet® zur Ovulationsinduktion. In diesem Versuchsabschnitt wurde der Einfluß verschiedener Intervalle zwischen der PMSG- und Gonavet®-Applikation geprüft. Das Zeitintervall betrug entsprechend der Versuchsvarianten bei den Jungsauen 80 bzw. 76 Stunden, bei den Altsauen mit mehr als zwei Würfen 58 bzw. 54 Stunden und bei den primiparen Sauen 72 bzw. 68 Stunden. Die beiden Inseminationen wurden jeweils 24 und 40 Stunden nach der Ovulationsinduktion durchgeführt. Im experimentellen Teil der Studie erfolgte die Analyse des Duldungsverhaltens, des Ovulationsverlaufes sowie die Beurteilung der Uteri und der Ovarien am 10. Tag nach der zweimaligen terminorientierten Besamung bei 79 Jungsauen der Deutschen Landrasse. Die Jungsauen wurden in vier Gruppen aufgeteilt. Die Versuchstiere der ersten drei Behandlungsvarianten erhielten zur Brunstsynchronisation über 15 Tage eine tägliche Dosis von 20 mg Altrenogest (5 ml Regumate®). Die Brunststimulation mittels 800 IE PMSG erfolgte entsprechend der Behandlungsvarianten 24, 36 bzw. 48 Stunden nach der letzten Regumate®-Gabe. In der vierten Versuchsvariante wurde den Jungsauen zur Zyklusblockade täglich 16 mg Altrenogest (4ml Regumate®) über das Kraftfutter verabreicht. Die PMSG-Applikation erfolgte 24 Stunden nach der letzten Regumate®-Gabe intramuskulär. Bei allen Jungsauen der experimentellen Versuchsdurchführung wurde die Ovulationsinduktion 80 Stunden nach der Brunststimulation mittels 500 IE hCG durchgeführt. 24 bzw. 40 Stunden nach der Ovulationsinduktion erfolgte die 1. bzw. 2. Insemination. Das Duldungs-verhalten wurde durch die zweimalige tägliche Kontrolle der Brunstsymptome in Anwesenheit eines fertilen Ebers erfaßt. Der Ovulationsverlauf sowie die Konzeptionsrate am 30. Trächtigkeitstag wurde durch die Anwendung der trans-kutanen Sonographie am unbeeinflußten stehenden Tier bestimmt. Nach der Schlachtung am 10. Tag nach der 1. Insemination wurden die Uteri gewogen und die Embryonen aus den Uterushörnern gewonnen. Desweiteren wurden die ovariellen Funktionskörper beurteilt und quantifiziert. Insgesamt konnten folgende Ergebnisse erzielt werden: · Untersuchungen in den Praxisbetrieben - Bei den Jung- und Altsauengruppen im Praxisbetrieb A konnte durch die Anwendung des GnRH-Analogon D-Phen6-LHRH (Gonavet®) zur Ovulations-induktion ein besseres Duldungsverhalten und ein stärkerer Synchronisations-effekt der Ovulation gegenüber dem Gonadotropin hCG festgestellt werden. Gleichfalls wurde durch die Verwendung des GnRH-Analogons eine höhere Konzeptionsrate erzielt. - Im Praxisbetrieb B wurde ein stärkeres Duldungsverhalten, eine geschlossenere Ovulation sowie eine um 13 % höhere Konzeptionsrate (84,1 %) der Jungsauen mit einem Zeitintervall: Brunststimulation - Ovulationsinduktion von 80 Stunden gegenüber den Tieren mit einem Zeitintervall von 76 Stunden ermittelt. - Durch die Verkürzung des Zeitintervalls zwischen der PMSG- und Gonavet®-Applikation von 58 auf 54 Stunden wurde bei den Altsauen mit mehr als 2 Würfen und einer 5wöchigen Säugezeit ein Anstieg der Variabilität im Ovulationsverlauf sowie eine um 1 % geringere Konzeptionsrate (80,7 %) beobachtet. - Auch bei einer Säugezeit von 5 Wochen sollte das Brunststimulations - Ovulationsinduktions-Intervall 72 Stunden bei den primiparen Sauen des Praxis-betriebes B betragen, da durch die Verlängerung des Zeitintervalls von 68 auf 72 Stunden eine bessere Synchronisation der Ovulation und eine um 11 % höhere Konzeptionsrate (83,9 %) festgestellt wurde. · Experimentelle Untersuchungen der Jungsauen - Durch die Verabreichung von 20 mg Altrenogest (5 ml Regumate®) gegenüber einer Dosierung von 16 mg Altrenogest (4 ml Regumate®) ist eine stärkere Synchronisation des Zyklus und ein geringerer Anteil von Jungsauen mit Zysten zu verzeichnen. - Das Zeitintervall zwischen letzter Brunstsynchronisation und Brunststimulation sollte 36 bzw. 48 Stunden betragen, da hierdurch bis zu 2,5 Embryonen mehr je Tier und eine bis zu 30 % geringerer Sauenanteil mit Zysten gegenüber den Jungsauen mit einem Intervall zwischen der PMSG- und GonavetÒ-Applikation von 24 Stunden ermittelt wurde. Durch die Untersuchung des Duldungsverhaltens und des Ovulationsverlaufes der Jung- und Altsauen war eine Einschätzung der Behandlungsvarianten der Ovulationssynchronisation mit terminorientierter Besamung unter praktischen und experimentellen Bedingungen möglich. Hierbei stellte die transkutane Sonographie 2 Stunden vor der 1. Insemination und 2 Stunden nach der 2. Insemination eine zuverlässige Methode dar, den termingerechten Ovulationszeitpunkt zu überprüfen. Das Duldungsverhalten und der Ovulationsverlauf sollten immer im Zusammenhang betrachtet werden, um die aus der biotechnischen Beeinflussung resultierenden Effekte richtig einschätzen zu können.In pig production the use of biotechnical methods to control the reproduction proces is a way to improve farm management factors and productivity. At the same time the use of hormones should be reduced to a minimum. The aim of the study was to gain further information on oestrus behaviour and the ovulation interval after different treatments of hormonally synchronized ovulation using fixed-time insemination of gilts and sows with transcutaneous sonography. The fertilization rate after the chosen treatment of synchronized sows should supply additional information for the different methods of treatment. In the first part of the study the oestrus behaviour and ovulation as well as the fertilization rate was analysed in 1742 gilts and sows on two animal farms. These farms use some of the current biotechnical treatments such as synchronization of ovulation by fixed-time insemination. Oestrus check was performed twice a daily to ascertain the time of insemination. The ovulation interval as well as the fertilization rate on the 30th day of pregnancy was determined using transcutaneous sonography on standing animals. Through using progestagene Altrenogest (Regumate®, Roussel Uclaf) all gilts of farm A underwent oestrus cycle suppression for 15 days. Oestros was induced using intramuscular PMSG injection administered in the gilts 24 hours after their last Regumate® dose and in sows after weaning. To induce ovulation, 500 IE hCG (Ekluton® 1500, Vemie Veterinär Chemie) or 25 µg of the GnRH-analogue D-Phen6-LHRH (Gonavet®, Veyx Pharma GmbH) were given corresponding to the treatments on farm A. The interval between both injections was 80 hours for gilts and 58 hours for sows. On farm B the sows were divided into two groups; sows after the first parity (primiparous sows, n = 214) and sows with more then parity 2 (parity range 3 to 11), because the biotechnical treatment on primiparous sows was modified on this farm. Induction of ovulation in gilts and primiparous sows was produced using 50 µg of GnRH-analogue Gonavet®. The sows (parity range 3 to 11) on the farm received 25 µg Gonavet® to induce ovulation. In this part of the trial the affect of different time intervals between the PMSG and Gonavet® dose was compared. The time interval was 80 or 76 hours for gilts, 58 or 54 hours for sows with more than two parities, and 72 or 68 hours for primiparous sows depending on the treatment. Two inseminations were carried in each gilt or sow out 24 and 40 hours after induction of ovulation. In the experimental part of the study oestrus behaviour, ovulation interval, and evaluation of uteri and the ovaries were analysed on 79 German Landrace gilts 10 days after the fixed-time inseminations. The gilts were divided into four groups according to the treatment methods. Three groups received a daily dose of 20 mg Altrenogest (5 ml Regumate®) over 15 days to synchronise oestrus. All three groups received 800 IE PMSG for induction of oestrus, but either 24, 36 or 48 hours after the last Regumate® dose respectively. The gilts in the fourth group were treated with a daily dose of 16 mg Altrenogest (4ml Regumate®) to suppress the oestrous cycle and were fed concentrates. The PMSG dose was given intramuscular 24 hours after the last Regumate® dose. All gilts of the experimental part of the trial received an injection with 500 IE hCG to induce ovulation 80 hours after oestrus induction. The 1st and 2nd insemination were performed 24 and 40 hours respectively after the induction of ovulation. The oestrus behaviour was examined by an oestrus check in presence of a fertile boar twice daily. The ovulation interval as well as the fertilization rate on the 30th day of conception was analysed using transcutaneous sonography on standing animals. All tested animals were slaughtered 10 days after the 1st insemination. The uteri were weighed and the embryos from the uterine horns were collected. The ovarian functional bodies were assessed and counted. In conclusion, the following results were achieved: · Investigation on the farms - GnRH-analogue D-Phen6-LHRH (Gonavet®) produced better oestrus behaviour and a stronger effect of synchronization of ovulation were observed in the gilt and sow groups on farm A compared to the use of gonadotrophin hormone hCG for induction of ovulation. Also a higher fertilization rate was achieved through administration of the GnRH-analogue. - For the gilts on farm B there was stronger oestrus behaviour, independent ovulation and a 13 % higher fertilization rate (84,1 %) from the 80 hours interval between oestrus induction and induction of ovulation compared to gilts with time interval of 76 hours. - For the sows with more than two parities and a 5 week suckling time, a greater variation of the ovulation interval and a 1 % lower fertilization rate (80,7 %) were observed when the time interval of PMSG and Gonavet® application was reduced from 58 to 54 hours. - Increasing the time interval between oestrus induction and induction of ovulation from 68 hours to 72 hours peoduced greater synchronization of ovulation and 11 % higher fertilization rate. Thus the time interval between oestrus induction and induction of ovulation for primiparous sows with a suckling time of 5 weeks on farm B should be 72 hours. · Experimental investigations on gilts - Greater synchronization of oestrous cycle and a decreased number of gilts with ovarian cysts were observed after administration of 20 mg Altrenogest (5 ml Regumate®) compared to a dose of 16 mg Altrenogest (4 ml Regumate®). - The time interval between the last oestrus synchronization and the oestrus induction should be 36 or 48 hours, because up to 2.5 embryos per gilt and up to 30 % fewer gilts with ovarian cysts were found, compared to gilts with a time interval of 24 hours. The analysis of oestrus behaviour and of ovulation interval on gilts and sows enabled an evaluation of different methods to synchronize ovulation with fixed-time insemination under practical and experimental conditions. In this study the transcutaneous sonography 2 hours before the 1st insemination and 2 hours after the 2nd insemination was a reliable method to ascertain the correct time of ovulation. Oestrus behaviour and the ovulation interval should always be used together to estimate the effects resulting from biotechnical manipulations

VennMaker para historiadores : fuentes, redes sociales y programas informáticos

Este artículo explora la aplicabilidad del programa informático VennMaker para la investigación histórica. El artículo se apoya en dos casos de estudio de investigaciones históricas actuales orientadas a estudiar las redes y que cubren diferentes periodos de tiempo y distintas fuentes. La mayor ventaja de VennMaker es que invierte el proceso de recolección de datos. Mientras que los programas tradicionales utilizan datos pre-codificados para producir el mapa de una red, VennMaker genera los datos mientras que el investigador dibuja los nodos y crea el mapa de una red. Las bases de datos de matrices prefabricadas ya no son necesarias; por lo tanto, el programa puede ser utilizado fácilmente por historiadores que no se han formado en las ciencias sociales. Los dos casos incluyen el análisis de una estructura familiar en la historia antigua y las redes ego-centradas de judíos que se escondían durante el Nacional-Socialismo. Artumentamos que una representación visual de las relaciones sociales ayuda a revelar modelos invisibles y caracerísticas de las redes que ofrecen a los investigadores nuevas perspectivas sobre sus temas de investigación. El programa ofrece una variedad de herramientas para representar las relaciones sociales y su desarrollo a lo largo del tiempo y del espacio.This paper explores the applicability of the software VennMaker to historical research. The paper draws on two case studies from current network-oriented historical research projects, covering different time periods and sources. VennMaker's biggest advantage is that it inverts the process of data collection. While traditional software uses pre-coded data to produce a network map, VennMaker generates data while the researcher draws nodes and creates a network map. Prefabricated data matrices are no longer necessary; therefore, the software can easily be used by historians lacking training in the social sciences. Our two cases include an analysis of a family structure in ancient history and ego-networks of Jews in hiding during National Socialism. We argue that a visual representation of social relations helps to reveal unseen patterns and characteristics of networks therefore offering scholars new perspectives on their research subjects. The software offers a variety of tools to represent social relations and their development over time and space

VennMaker for Historians : sources, social networks and software

This paper explores the applicability of the software VennMaker to historical research. The paper draws on two case studies from current network-oriented historical research projects, covering different time periods and sources. VennMaker's biggest advantage is that it inverts the process of data collection. While traditional software uses pre-coded data to produce a network map, VennMaker generates data while the researcher draws nodes and creates a network map. Prefabricated data matrices are no longer necessary; therefore, the software can easily be used by historians lacking training in the social sciences. Our two cases include an analysis of a family structure in ancient history and ego-networks of Jews in hiding during National Socialism. We argue that a visual representation of social relations helps to reveal unseen patterns and characteristics of networks therefore offering scholars new perspectives on their research subjects. The software offers a variety of tools to represent social relations and their development over time and space.Este artículo explora la aplicabilidad del programa informático VennMaker para la investigación histórica. El artículo se apoya en dos casos de estudio de investigaciones históricas actuales orientadas a estudiar las redes y que cubren diferentes periodos de tiempo y distintas fuentes. La mayor ventaja de VennMaker es que invierte el proceso de recolección de datos. Mientras que los programas tradicionales utilizan datos pre-codificados para producir el mapa de una red, VennMaker genera los datos mientras que el investigador dibuja los nodos y crea el mapa de una red. Las bases de datos de matrices prefabricadas ya no son necesarias; por lo tanto, el programa puede ser utilizado fácilmente por historiadores que no se han formado en las ciencias sociales. Los dos casos incluyen el análisis de una estructura familiar en la historia antigua y las redes ego-centradas de judíos que se escondían durante el Nacional-Socialismo. Artumentamos que una representación visual de las relaciones sociales ayuda a revelar modelos invisibles y caracerísticas de las redes que ofrecen a los investigadores nuevas perspectivas sobre sus temas de investigación. El programa ofrece una variedad de herramientas para representar las relaciones sociales y su desarrollo a lo largo del tiempo y del espacio

Design and experiments to investigate spray and impingement characteristics of a common rail type lubrication system

[EN] This paper reports on the establishment of a testing facility to investigate spray and impingement characteristics of a recently developed, fully adaptive lubrication system for large two stroke marine diesel engines. The reported part of this research relates to development steps towards the new lubrication system as well as the implementation of a dedicated testing facility and the establishment of validation approaches in order to corroborate technology developments in this context. The major objective of this development yields an optimization of lubricant utilization and at the same time a significant reduction of lubricant fraction in the exhaust gas. A requisite to obtain the desired level of flexibility calls for a revised approach in injecting the lubricant. The desired flexibility of the new lubrication approach foresees a cycle based adjustment of the injected amount of lubricant as well as the injection pressure in order to provide the possibility to shape the injection spray pattern. Concept studies nominate the application of a common rail system with integrated needle lift type injectors and adjustable injection pressure as compliant with the requisite to inject the lubricant with a high level of flexibility. This paper hence encompasses design and development aspects of the new lubrication system but most of all highlights steps in developing a validation concept in order to compare common lubrication systems with the new type of lubrication system. Initial results of the test cell provide an insight regarding relevant information on the injection spray characteristics over the full engine load range as well as the possibility to compare common lubrication system performance with the new common rail lubrication system. A comparison between measurement and simulation results provide the possibility to implement experimentally gained data in a neuronal network in order to enhance the predictive quality of the simulation tool.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 634135Stark, M.; De Risi, A.; Giangreco, M.; Diggelmann, S. (2017). Design and experiments to investigate spray and impingement characteristics of a common rail type lubrication system. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 772-780. https://doi.org/10.4995/ILASS2017.2017.468877278

Benefits and obstacles of sustainable product development methods : a case study in the field of urban mobility

In the last few years, numerous approaches have been introduced for supporting design engineers in developing more sustainable products. However, so far, these efforts have not led to the establishment of a commonly acknowledged standard methodology for Sustainable Product Development (SPD). This brings into question the relevance of developing new methods and calls for more efforts in testing the available ones. This article provides a reflection about the benefits and obstacles of applying existing SPD approaches to a real product development project. It reports the results of a project aimed at developing a new mobility solution under the constraints of sustainability-related targets. This project has led to the development of a new pedelec concept, focusing on the substitution of small passenger cars with the help of three SPD methods – Design for Sustainability Guidelines, Product Sustainability Index, and Life Cycle Sustainability Assessment. These methods have proved to be generally beneficial, thanks to a combination of qualitative and quantitative perspectives. However, the multitude of criteria offered by the methods put forth difficulties in evaluating which sustainability aspects are relevant and therefore lead to higher effort for information retrieval analysis and decision processes. Furthermore, the methods still lack an integrated perspective on the product, the corresponding services and the overarching system.DFG, 325093850, Open Access Publizieren 2017 - 2018 / Technische Universität Berli

Characteristics and risk factors for symptomatic Giardia lamblia infections in Germany

Background: In developed countries, giardiasis is considered a travel related disease. However, routine surveillance data from Germany indicate that >50% of infections were acquired indigenously. We studied the epidemiological characteristics of symptomatic Giardia infections acquired in Germany and abroad, and verified the proportion of cases acquired in Germany in order to investigate risk factors for sporadic autochthonous Giardia infections. Methods: We identified Giardia cases notified by 41 local health authorities between February 2007 and January 2008 and interviewed them on their clinical symptoms, underlying morbidities, travel abroad and potential risk factors for the disease. We conducted a case-control-study including laboratory-confirmed (microscopy or antigen-test) autochthonous Giardia cases with clinical manifestations (diarrhoea, cramps, bloating) and randomly selected controls from the local population registry matched by county of residence and age-group (0-5, 6-19, ≥20 years). Secondary cases, controls with diarrhoea and persons who had travelled outside Germany in the three weeks prior to disease onset (exposure period) were excluded. We calculated adjusted odds ratios (aOR) with 95% confidence intervals (CI) using conditional logistic regression. Results: Of 273 interviewed cases, 131 (48%) had not travelled abroad during the defined exposure period. Of these 131, 85 (65%) were male, 68 (54%) were living in communities with >100,000 inhabitants and 107 (83%) were aged 20 years or older. We included 120 cases and 240 controls in the case-control study. Cases were more likely to be male (aOR 2.5 CI 1.4-4.4), immunocompromised (aOR 15.3 CI 1.8-127) and daily consumers of green salad (aOR 2.9 CI 1.2-7.2). Contact with animals (pets/farm animals) and exposure to surface water (swimming/water sports) were not associated with symptomatic disease. Conclusions: A substantial proportion of Giardia lamblia cases in Germany are indigenously acquired. Symptomatic cases are significantly more likely to be immunocompromised than control persons from the general population. Physicians should consider Giardia infections among patients with no recent history of travel abroad, particularly if they have immune deficiencies. Green salads may be an important vehicle of infection. Information campaigns highlighting this food-borne risk should emphasise the risk to persons with immune deficiencies

Physical State of Molecular Gas in High Galactic Latitude Translucent Clouds

The rotational transitions of carbon monoxide (CO) are the primary means of investigating the density and velocity structure of the molecular interstellar medium. Here we study the lowest four rotational transitions of CO towards high-latitude translucent molecular clouds (HLCs). We report new observations of the J = (4-3), (2-1), and (1-0) transitions of CO towards eight high-latitude clouds. The new observations are combined with data from the literature to show that the emission from all observed CO transitions is linearly correlated. This implies that the excitation conditions which lead to emission in these transitions are uniform throughout the clouds. Observed 13CO/12CO (1-0) integrated intensity ratios are generally much greater than the expected abundance ratio of the two species, indicating that the regions which emit 12CO (1-0) radiation are optically thick. We develop a statistical method to compare the observed line ratios with models of CO excitation and radiative transfer. This enables us to determine the most likely portion of the physical parameter space which is compatible with the observations. The model enables us to rule out CO gas temperatures greater than 30K since the most likely high-temperature configurations are 1 pc-sized structures aligned along the line of sight. The most probable solution is a high density and low temperature (HDLT) solution. The CO cell size is approximately 0.01 pc (2000 AU). These cells are thus tiny fragments within the 100 times larger CO-emitting extent of a typical high-latitude cloud. We discuss the physical implications of HDLT cells, and we suggest ways to test for their existence.Comment: 19 pages, 13 figures, 2 tables, emulateapj To be published in The Astrophysical Journa