How to Reach a Thousand-Second in-Plane Polarization Lifetime with 0.97-GeV/c Deuterons in a Storage Ring

We observe a deuteron beam polarization lifetime near 1000 s in the horizontal plane of a magnetic storage ring (COSY). This long spin coherence time is maintained through a combination of beam bunching, electron cooling, sextupole field corrections, and the suppression of collective effects through beam current limits. This record lifetime is required for a storage ring search for an intrinsic electric dipole moment on the deuteron at a statistical sensitivity level approaching 10^{-29}  e cm.

Search for Lorentz and CPT violation effects in Muon spin precession

The spin precession frequency of muons stored in the (g-2) storage ring has been analyzed for evidence of Lorentz and CPT violation. Two Lorentz and CPT violation signatures were searched for a nonzero delta omega a(=omega a mu+ - omega a mu-) and a sidereal variation of omega a mu+/-). No significant effect is found, and the following limits on the standard-model extension parameters are obtained: bZ = -(1.0+/-1.1) x 10(-23) GeV; (m mu dZ0 + HXY)=(1.8+/-6.0) x 10(-23) GeV; and the 95% confidence level limits b perpendicular mu+ <1.4 x 10(-24) GeV and b perpendicular mu- <2.6 x 10(-24) GeV.

Measurement of the negative muon anomalous magnetic moment to 0.7 ppm

The anomalous magnetic moment of the negative muon has been measured to a precision of 0.7 ppm (ppm) at the Brookhaven Alternating Gradient Synchrotron. This result is based on data collected in 2001, and is over an order of magnitude more precise than the previous measurement for the negative muon. The result a(mu(-))=11 659 214(8)(3) x 10(-10) (0.7 ppm), where the first uncertainty is statistical and the second is systematic, is consistent with previous measurements of the anomaly for the positive and the negative muon. The average of the measurements of the muon anomaly is a(mu)(exp)=11 659 208(6) x 10(-10) (0.5 ppm).

Measurement of the positive muon anomalous magnetic moment to 0.7 ppm

A higher precision measurement of the anomalous g value, a(mu)=(g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron, based on data collected in the year 2000. The result a(mu(+))=11 659 204(7)(5)x10(-10) (0.7 ppm) is in good agreement with previous measurements and has an error about one-half that of the combined previous data. The present world average experimental value is a(mu)(expt)=11 659 203(8)x10(-10) (0.7 ppm).

Freezing of gait in patients with advanced Parkinson's disease

BACKGROUND

Freezing of Gait (FOG) is one of the most disturbing and least understood symptom in advanced stage of Parkinson's disease (PD). The contribution of the underlying pathological process and the antiparkinsonian treatment to the development of FOG are controversial.

OBJECTIVE

To study the relationships between clinical features of PD and therapeutic modalities in patients with advanced PD and FOG.

METHODS

Consecutive patients with 5 years or more of PD symptoms (n = 172) (99 men) with mean age at symptoms onset of 58.3 +/- 13.2 years and mean symptoms duration of 11.8 +/- 5.6 years were studied. Clinical data were collected during the last office visit through physical examination, detailed history, review of patients' charts, and other documents. A patient was considered as "freezer" if he/she reported recent experience that the legs got stuck to the ground while trying to walk. The presence of dyskinesia, early morning dystonia or significant postural reflex abnormalities were assessed through history and neurological examination. Duration of treatment with antiparkinsonian drugs was calculated from history charts. Chi square and t test were used to compare the patients with and without FOG. Logistic regression was used for the comparison of association between the presence of FOG (dependent variable) disease duration and disease stage (explanatory variables) and duration of treatment with anti-parkinsonian drugs.

RESULTS

The study population consisted of 45 patients at Hoehn and Yahr (H&Y) stage 2.5 (26%), 104 patients at stage 3 (60.5%), and 23 patients at H&Y stages 4-5 (13.5%). Ninety one patients (53%) reported FOG at the time of the study. Severity of the disease expressed by H&Y stage at "off" was a significant contributing factor for FOG with a significant trend (z = 4.38, p < 0.0001), as was longer duration of levodopa treatment, and confirmed by FOG using the multivariate logistic regression (p = 0.01 and p = 0.004, respectively). Using a univariate model, longer duration of treatment with dopamine agonists contribute to the appearance of FOG (p = 0.07) while longer duration of amantadine treatment decreased the appearance of FOG (p = 0.09). There was a significant association between FOG and the presence of dyskinesia (p < 0.002), early morning foot dystonia (p < 0.003) and significant postural instability (p < 0.0005).

CONCLUSION

FOG is a common symptom in advanced PD. It is mainly related to disease progression and levodopa treatment.

Precise measurement of the positive muon anomalous magnetic moment

A precise measurement of the anomalous g value, a(mu) = (g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron. The result a(mu+) = 11 659 202(14) (6) x 10(-10) (1.3 ppm) is in good agreement with previous measurements and has an error one third that of the combined previous data. The current theoretical value from the standard model is a(mu)(SM) = 11 659 159.6(6.7) x 10(-10) (0.57 ppm) and a(mu)(exp) - a(mu)(SM) = 43(16) x 10(-10) in which a(mu)(exp) is the world average experimental value.

Risk factors for dementia, depression and psychosis in long-standing Parkinson's disease

OBJECTIVES

To study the relationships between clinical features of Parkinson's disease (PD) and the development of dementia, depression or psychosis in patients with long-standing disease.

BACKGROUND

The natural history of dementia and depression in PD, and its relation to psychosis in long standing PD, are unclear.

METHOD

172 consecutive patients (99 men and 73 women, mean age at symptoms onset 58.3 +/- 13.2 years) with 5 years or more of PD (mean symptom duration of 11.8 +/- 5.6 years) were studied. Clinical data were collected during the last office visit through physical examination, detailed history, review of patient charts and outside documents. Dementia and depression were diagnosed according to DSM-IV criteria, while psychosis was diagnosed if hallucinations or delusions were present. Chi-square and t tests were used to compare the patient characteristics among those with vs. those without mental complications of the disease at different disease stages. Logistic regression was used for the comparison of associations between the presence of dementia or depression (dependent variable) and age at onset of PD, duration of PD and disease staging (explanatory variables).

RESULTS

The study population consisted of 45 patients at Hoehn & Yahr (H&Y) stage < or = 2.5 (26%), 104 patients at stage 3 (60.5%) and 23 patients at H&Y stage 4-5 (13.5%). Sixty one patients (36%) had dementia, 55 patients had depression (33%) and 50 patients (27%) had psychosis. Dementia and depression were significantly associated with disease severity as reflected in the H&Y scale (P = 0.0003, Z = 3.59; P = 0.006, Z = 3.22, respectively). These associations were significant also for the older age of PD onset (> or = 59 years n = 89) subgroup (p = 0.001, Z = 3.2 for dementia and p = 0.02, Z = 2.9 for depression), but not for younger onset cases (< 59 years n = 83). Dementia was significantly associated with older age of PD onset (beta = 0.04, p = 0.009) while depression was inversely associated with age of PD onset (beta = -0.04, p = 0.02). The presence of dementia was also significantly associated with depression (beta = 1.49, p = 0.0006). Dementia and depression were found to be independent explanatory variables for the development of psychosis (logistic regression, odds ratio (OR) = 26.0, p < 0.0001; OR = 10.2, p < 0.0001, respectively). In patients with younger age of PD onset, depression more than dementia was strongly correlated with the appearance of psychosis.

CONCLUSION

Dementia in PD was related to older age of symptoms onset and old age. Depression was associated with dementia or early age of PD onset. Depression seemed to contribute to the appearance of psychosis even more than dementia, especially in patients with younger age of symptoms onset.

Anal sphincter EMG does not distinguish between multiple system atrophy and Parkinson's disease

Clinical distinction of multiple system atrophy (MSA) from Parkinson's disease (PD) is often difficult. Several recent reports indicate that objective classification may be accomplished using electromyographic (EMG) testing of the anal or urethral sphincters, but some authors have found that these tests are not reliable for this purpose. We studied 13 patients with PD and 10 with probable MSA, as diagnosed by consensus of four movement disorders specialists, according to accepted clinical criteria. Anal sphincter EMG was performed blind to the clinical diagnosis. We found no significant differences in the mean duration of motor unit potentials (MUPs), mean MUP amplitude, or prevalence of polyphasic potentials, satellite potentials, very long duration MUPs, or spontaneous activity between the two groups. Thus, anal sphincter EMG does not differentiate between PD and MSA.