A multilevel finite element-multibody approach to design the suspension system for the road transportation of SSR1 cryomodule

Cryomodules (CM) represents edge-frontier assemblies in particle physics research field. The road transportation of CM is a critical phase during which the structures can be subjected to significant dynamic loads. It is therefore necessary to design a Transportation Tool (TT) equipped with an appropriate suspension system. This work describes the approach adopted for the design of the TT for the CM PIP-II SSR1 (Proton Improvement Plan-II – Single Spoke Resonators 1), which is firstly introduced in the CM research field. Initially a Finite Element (FE) model was developed, considering the main sub-assemblies of the CM. However, this model was not suitable for the design of the TT due to the high computational burden. For this reason the model was exported as a Modal Neutral File and imported into a MultiBody software (MB) where the remaining components were modeled as concentrated stiffnesses or rigid bodies. The MB model thus obtained has drastically reduced the calculation time, proving to be fundamental in the TT iterative design phase, which involves the use of Helical Isolators (HI) performing the function of mechanical filters. To validate the effectiveness of TT in reducing dynamic loads, a 3D acceleration profile measured during the transport of a similar cryomodule (Linear Coherent Light Source II, LCLS-II) was used. Furthermore, the results of the MB model were used to perform the structural verification of some critical components of the CM

Human germline heterozygous gain-of-function STAT6 variants cause severe allergic disease

STAT6 (signal transducer and activator of transcription 6) is a transcription factor that plays a central role in the pathophysiology of allergic inflammation. We have identified 16 patients from 10 families spanning three continents with a profound phenotype of early-life onset allergic immune dysregulation, widespread treatment-resistant atopic dermatitis, hypereosinophilia with esosinophilic gastrointestinal disease, asthma, elevated serum IgE, IgE-mediated food allergies, and anaphylaxis. The cases were either sporadic (seven kindreds) or followed an autosomal dominant inheritance pattern (three kindreds). All patients carried monoallelic rare variants in STAT6 and functional studies established their gain-of-function (GOF) phenotype with sustained STAT6 phosphorylation, increased STAT6 target gene expression, and TH2 skewing. Precision treatment with the anti-IL-4Rα antibody, dupilumab, was highly effective improving both clinical manifestations and immunological biomarkers. This study identifies heterozygous GOF variants in STAT6 as a novel autosomal dominant allergic disorder. We anticipate that our discovery of multiple kindreds with germline STAT6 GOF variants will facilitate the recognition of more affected individuals and the full definition of this new primary atopic disorder

Innovative mechanical design and development of single spoke resonators with microphonics control for the next generation of superconducting particle accelerators

Frequency detuning of accelerating structures is a technical challenge for the next generation of superconducting linear particle accelerators operating in continuous wave (CW) or pulsed regime with a low beam current. In such machines, any drift in the operating frequency (few tens of Hz) would get the cavities seriously detuned from their resonant frequencies, causing phase errors that negatively affect the beam. To address this issue of frequency detuning, an innovative methodology was developed to design and fabricate a new generation of low-beta superconducting single spoke resonators (or cavities) with a very low sensitivity to microphonics. The liquid helium containment vessel surrounding the Single Spoke Resonator of type 1 (SSR1) was designed such that the fluctuations of the helium bath do not cause substantial radio-frequency detuning. The structural design was carried out following the American Society of Mechanical Engineers (ASME) Code whenever possible. Alternative procedures were established to deal with any exception encountered and produce a level of safety consistent with that of the Code. The tuning mechanism for the active adjustment of the resonant frequency of the cavity was also designed and developed. Experimental tests were performed on fabricated prototypes to verify the validity of the design and fabrication approach. The systematic application of this design approach to other SRF cavities will allow consistent capital and operational costs savings, possibly totaling millions of dollars, for the next generation of superconducting particle accelerators, such as the Proton Improvement Plan-II (PIP-II) at Fermilab

Analisi del comportamento meccanico della cavita superconduttrice SSR1 nei test a temperatura criogenica a Fermilab

Il seguente elaborato è frutto di un'esperienza semestrale presso Technical Division del Fermilab di Chicago (Illinois, USA), Dipartimento Superconductivity and Radio Frequency Development, nel gruppo di lavoro dell'ingegner Leonardo Ristori. L'esperienza inizia nell'aprile 2010 con una serie di 'training' atti a formare ed informare i lavoratori Fermilab sulle varie regole vigenti, spaziando dalle norme e procedure di sicurezza fino a nozioni tecniche sulla politica di raggiungimento degli obiettivi. Le attività svolte nella prima parte di tale periodo, hanno avuto come oggetto lo studio del comportamento strutturale della Cavità tipo Single Spoke Resonator type 1 (SSR1), soggetta a differenti sollecitazioni di natura termica e meccanica. In sostanza sono state implementate una serie di simulazioni agli elementi finiti, riproducenti alcune fasi della campagna di test sperimentali, al fine di estrapolarne informazioni utili per la regolazione (setting) di alcuni componenti, prima e durante l'esecuzione dei test. Si è colta l'occasione per valutare anche la bontà del design in termini di resistenza e rigidezza, adoperando le proprietà dei materiali ricavate da prove sperimentali e testi di letteratura. Nella seconda parte l'attenzione si è focalizzata su un particolare componente della SSR1: il Tuner. Dopo un primo studio volto alla caratterizzazione meccanica, in termini di rigidezza, nelle principali configurazioni d'uso, sono stati analizzati criticamente tali valori con l'obiettivo di trovare possibili migliorie apportabili al design del Tuner, e ottenere quindi migliori performance strutturali del sistema Tuner/Cavità. Le modifiche effettuate sono di tipo qualitativo, lasciando ad altri una trattazione di tipo quantitativa, dimostrando soltanto la presenza di margini di miglioramento

Financial Systemic Risk: Taxation or Regulation?

In this paper we describe systemic financial risk as a pollution issue. Free riding leads to excess risk production. This problem may be solved, at least partially, either with financial regulation or taxation. From a normative viewpoint taxation is superior in many respects. However, reality shows that financial regulation is more frequently adopted. In this paper we make a positive, politico-economic argument. If the majority chooses a tax, then it is likely to be too low. If it chooses regulation it will possibly be too harsh. Moreover, a majority of low polluting portfolio owners may strategically use regulation in order to charge the minority a larger share of the externality reduction.financial crises, banking regulation, financial transaction taxes

Populism and Central Bank independence

The populist narrative hinges on the feeling of frustration with the current situation. This SUERF Policy Note focuses on financial inequality, populism and central bank independence, shedding light on the relationships between aggrievement in the electorate and large financial inequality, the advancement of populist parties and the risk that myopic policies are going to be adopted. In such a situation a populist policy that promotes a politically controlled central bank that is perceived as a technocratic elite it is more likely to occur

The Financial Transaction Tax A Political Economy View

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Populism, political pressure and central bank (in)dependence

This article analyses the relationships between inequality, political pressure, populism and central bank independence (CBI). If there is financial inequality across citizens, monetary policies yield distributional consequences. Political pressure on central bank will increase. A populist wave fuelled by large demand for redistribution with no regard to long term consequences may undermine actual CBI