Typical features of Parkinson disease and diagnostic challenges with microdeletion 22q11.2

Objective: To delineate the natural history, diagnosis, and treatment response of Parkinson disease (PD) in individuals with 22q11.2 deletion syndrome (22q11.2DS), and to determine if these patients differ from those with idiopathic PD. Methods: In this international observational study, we characterized the clinical and neuroimaging features of 45 individuals with 22q11.2DS and PD (mean follow-up 7.5 ± 4.1 years). Results: 22q11.2DS PD had a typical male excess (32 male, 71.1%), presentation and progression of hallmark motor symptoms, reduced striatal dopamine transporter binding with molecular imaging, and initial positive response to levodopa (93.3%). Mean age at motor symptom onset was relatively young (39.5 ± 8.5 years); 71.4% of cases had early-onset PD (<45 years). Despite having a similar age at onset, the diagnosis of PD was delayed in patients with a history of antipsychotic treatment compared with antipsychotic-naive patients (median 5 vs 1 year, p = 0.001). Preexisting psychotic disorders (24.5%) and mood or anxiety disorders (31.1%) were common, as were early dystonia (19.4%) and a history of seizures (33.3%). Conclusions: Major clinical characteristics and response to standard treatments appear comparable in 22q11.2DS-associated PD to those in idiopathic PD, although the average age at onset is earlier. Importantly, treatment of preexisting psychotic illness may delay diagnosis of PD in 22q11.DS patients. An index of suspicion and vigilance for complex comorbidity may assist in identifying patients to prioritize for genetic testing

Ice crystal properties retrieval using radar spectral polarimetric measurements within ice/mixed-phase clouds

In the field of atmospheric research, ground-based radar systems are often employed to study ice/mixed-phase cloud properties based on retrieval techniques. These techniques convert the radar signal backscattered by each bulk of ice crystals being probed within the same radar resolution volume to cloud’s microphysical characteristics. However, the size of a radar resolution volume is often too large compared to the microphysical and thermodynamical variability of the atmosphere. The microphysical information contained in the radar signal is then complex and difficult to retrieve. Therefore, the ground-based observations of the cloud’s particles microphysical characteristics are a real challenge in atmospheric science. In this thesis, an advanced atmospheric profiling radar (TARA - IRCTR) simultaneously uses Doppler and polarimetric capabilities in order to characterise the microphysical properties of the ice crystals present in ice/mixed-phase clouds. On the one hand, the polarimetric response of an atmospheric target is related to its axis ratio, assuming a spheroidal shape. On the other hand, the Doppler effect induced by the particle motion is measured by the radar and is referred as particle radial velocity. Therefore, compared to conventional weather radars, Doppler-polarimetric measurements better describe the radar resolution volume of ice particles which are categorised according to particle shape and velocity (see Chapter 3). The main objective of this PhD thesis is to develop a new type of retrieval technique, where the microphysical characteristics of ice / mixed-phase clouds are obtained from the radar spectral polarimetric measurements. High data quality is required for the reliability of spectral polarimetric parameters. Thus, a specific signal processing is performed for each radar cell, so that noise and clutter free radar parameters are obtained. Moreover, the atmospheric instability effect on radar signal data has to be removed by correctly averaging the signal over time. A strong point of this thesis comes from the derivation of averaging on a radar cell basis, based on a statistical study of the spectral polarimetric parameters determining the time slots of the atmospheric instability (see Chapter 4). In Chapter 5, a microphysical model for the study of ice crystals conversion into raindrops was improved in order to relate the ice crystals properties of ice/mixed-phase cloud regions to spectral polarimetric data. The model is based on different relations which take into account the particle habit (assuming spheroidal shapes) and orientation, ice crystals’ maximum size and their size distribution (assuming that particles fit in a modified gamma distribution). The model for ice/mixed-phase cloud study was enhanced, following these three points: 1) the implementation of the column-like pristine ice, 2) the implementation of the vertical orientation of the ice particles; and 3) a full sensitivity analysis of the input as well as model related parameters. The major breakthrough of this thesis is described in Chapter 6 with the development of a new microphysical retrieval technique. For the first time, a detailed microphysical analysis of the ice crystals present in ice/mixed-phase clouds is obtained, at each radar cell, from the sole use of TARA radar (Transportable Atmospheric Radar) Doppler polarimetric measurements. The spectral polarimetric parameters are first used to determine the type of ice particles present in the radar resolution volume, relating to their main orientation, main size and habit. The model described in Chapter 5 is then applied to the retrieval technique, as a forward model, in order to determine the mean ambient radial wind velocity and the three free parameters of the modified gamma distribution referring to each particle type. The retrieval technique was tested for a specific meteorological condition during the COPS (Convective and Orographically-induced Precipitation Study) measurement campaign, in summer 2007. As seen in Chapter 7, the microphysical results and the interpretation of the cloud processes obtained so far, within a convective nimbostratus cloud, showed good spatial and time regularity. The radar measurement results were compared and validated with other collocated sensors. The comparison of the microphysical cloud properties of a similar cloud condition was achieved with collocated aircraft measurements, flying over the ground-based site. The mean Ice Water Content (IWC), the mean ice Total Number Concentration (Nt) and the shape of the PSD, retrieved and measured by the ATR42 aircraft, were found in good agreement.TelecommunicationsElectrical Engineering, Mathematics and Computer Scienc

Towards the improvement of cloud microphysical retrievals using simultaneous Doppler and polarimetric radar measurements

Radar-based retrievals are often employed to characterize the microphysical properties of cloud hydrometeors, i.e. their phases, habits, densities as well as their respective size and orientation distributions. These techniques are based on a synergetic use of different cloud observation sensor(s) and microphysical model(s) where the information extracted from both sensors and models is combined and converted into microphysical cloud properties. However, the amount of available information is often limited, which forces current microphysical retrieval techniques to base their algorithms on several microphysical assumptions which affect the retrieval accuracy. By simultaneously combining Doppler and polarimetric measurements obtained from fully Doppler polarimetric radars, it is possible to create spectral polarimetric parameters. Although these parameters are easily contaminated with unwanted echoes, this work shows that, from a correct radar signal processing based on filtering and averaging techniques, spectral polarimetric parameters can be correlated to microphysical cloud properties. In particular, preliminary results suggest that particle orientations and habits can be determined from the sole use of such spectral polarimetric parameters. Therefore, such additional spectral polarimetric information offers an opportunity to improve current microphysical retrievals by reducing the number of microphysical assumptions in them.TelecommunicationsElectrical Engineering, Mathematics and Computer Scienc

Influence of the liquid layer within mixed-phase clouds on radar observations

Mixed-phase clouds play an important role in the earth system. They affect earth radiative balance and the climate (Comstock et al., 2007; Solomon et al., 2007) as well as the formation of precipitation (de Boer et al., 2009; Fan et al., 2011; Lamb and Verlinde, 2011). Within such mixed-phase clouds supercooled water droplets and ice particles are coexisting in the same volume and interact via microphysical processes (Shupe et al., 2008). This processes lead to growing of ice particles via Wegener-Bergeron-Findeisen process (Fan et al., 2011), riming, and/or aggregation (Lamb and Verlinde, 2011). In theory (Fan et al., 2011; Lamb and Verlinde, 2011) and in laboratory experiments (Fukuta and Takahashi, 1999) this processes are well described. Observing such processes within mixed-phase clouds is still a challenge and closely connected to the two phases and their interaction. To measure all the different properties of the hydrometeors nowadays a synergy of different instruments have to be used (de Boer et al., 2011; Shupe et al., 2008; Verlinde et al., 2013). One of the main goals is to get a better understanding of such effects of supercooled water droplets on ice crystals within mixed-phase clouds. A first step is therefore to be able to separate liquid and ice phase within such clouds. To be able to do this for any kind on mixed phase cloud type this paper show the development of a radar-based technique which allow such observations for different cloud types. This technique is also compared with standard ones using a synergy with lidar and/or microwave radiometer.Geoscience & Remote SensingCivil Engineering and Geoscience

Retrieving fall streaks within cloud systems using doppler radar

The interaction of ice crystals with supercooled liquid droplets in mixed-phase clouds leads to an enhanced growth of ice particles. However, such processes are still not clearly understood although they are important processes for precipitation formation in midlatitudes. To better understand how ice particles grow within such clouds, changes in the microphysical parameters of a particle population falling through the cloud have to be analyzed. The Transportable Atmospheric Radar (TARA) can retrieve the full 3D Doppler velocity vector based on a unique three-beam configuration. Using the derived wind information, a new fall streak retrieval technique is proposed so that microphysical changes along those streaks can be studied. The method is based on Doppler measurements only. The shown examples measured during the Analysis of the Composition of Clouds with Extended Polarization Techniques (ACCEPT) campaign demonstrate that the retrieval is able to capture the fall streaks within different cloud systems. These fall streaks can be used to study changes in a single particle population from its generation (at cloud top) until its disintegration. In this study fall streaks are analyzed using radar moments or Doppler spectra. Synergetic measurements with other instruments during ACCEPT allow the detection of liquid layers within the clouds. The estimated microphysical information is used here to get a better understanding of the influence of supercooled liquid layers on ice crystal growth. This technique offers a new perspective for cloud microphysical studies.Atmospheric Remote SensingGeoscience and Remote Sensin

The new real-time measurement capabilities of the profiling TARA radar

In the past 10 years, the S-band FM-CW TARA (Transportable Atmospheric RAdar), placed at the Cabauw Experimental Site for Atmospheric Research (CESAR), provided in real-time vertical profiles of the Doppler moments. Classical spectral processing was carried out. The polarimetric and multi-beam measurement capabilities of the radar were not exploited in real-time. It was only possible to acquire raw data for case studies. Based on them, new algorithms were developed using spectral polarimetry and the multi-beam capability of TARA. They have been tested during the COPS (2007) and EUCAARI-IMPACT campaigns (2008). To measure in real-time the Doppler moments of three beams, the differential reflectivity, the linear depolarization ratio, the horizontal wind and the vertical mean Doppler velocity, it became necessary to upgrade TARA. This resulted in a new design of the radar control unit and a new processing based on spectral polarimetry. This major upgrade took place in 2011. TARA can now deliver multi-parameters profiles with high spatial and time resolution and raw data in real-time. They are stored with the NetCDF format. Furthermore, detailed quick-looks of all the observables are available in real-time at http://ftp.tudelft.nl/TUDelft/irctr-rse/tara/index.html. For the design of the radar control unit and processing, a flexible solution that can process the data in a high level programming language, was chosen. This was done to be able to easily implement future developments in radar signal processing and algorithms.Geoscience & Remote SensingCivil Engineering and Geoscience

Observing ice particle growth along fall streaks in mixed-phase clouds using spectral polarimetric radar data

The growth of ice crystals in presence of supercooled liquid droplets represents the most important process for precipitation formation in the mid-latitudes. However, such mixed-phase interaction processes remain relatively unknown, as capturing the complexity in cloud dynamics and microphysical variabilities turns to be a real observational challenge. Ground-based radar systems equipped with fully polarimetric and Doppler capabilities in high temporal and spatial resolutions such as the S-band transportable atmospheric radar (TARA) are best suited to observe mixed-phase growth processes. In this paper, measurements are taken with the TARA radar during the ACCEPT campaign (analysis of the composition of clouds with extended polarization techniques). Besides the common radar observables, the 3-D wind field is also retrieved due to TARA unique three beam configuration. The novelty of this paper is to combine all these observations with a particle evolution detection algorithm based on a new fall streak retrieval technique in order to study ice particle growth within complex precipitating mixed-phased cloud systems. In the presented cases, three different growth processes of ice crystals, plate-like crystals, and needles are detected and related to the presence of supercooled liquid water. Moreover, TARA observed signatures are assessed with co-located measurements obtained from a cloud radar and radiosondes. This paper shows that it is possible to observe ice particle growth processes within complex systems taking advantage of adequate technology and state of the art retrieval algorithms. A significant improvement is made towards a conclusive interpretation of ice particle growth processes and their contribution to rain production using fall streak rearranged radar data.Atmospheric Remote SensingGeoscience and Remote Sensin

ACCEPT campaign (Analysis of the Composition of Clouds with Extended Polarization Techniques) data set 07-11-2014

Measurement of the Transportable Atmospheric Radar (TARA), operated by the TU Delft located at the Cabauw Experimental Side for Atmospheric Research (CESAR), Cabauw, The Netherlands. Data are obtained during the Analysis of the Composition of Clouds with Extended Polarization Techniques ACCEPT-Campaign, fall 2014. The date contains the measured radar moments and examples of spectral radar measurements. Only data with the highest temporal time resolution are provided

Polarimetric weather signatures and Doppler spectral analysis of a convective squall line

Geoscience and Remote SensingCivil Engineering and Geoscience